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Chapter Text

Katsuki

“Give me the knife, Kacchan,” said Izuku as he tried to pull at Katsuki’s wrists.

“Shut it.” Katsuki fully ignored him, continuing to press the cloth to Izuku’s profusely bleeding neck.

It was doing nothing. They both knew it, but Katsuki refused to stop trying.

“Please,” Izuku begged. He tried to catch Katsuki’s eye, but Katsuki was focused on the wound on his neck.  

Katsuki avoided his gaze, scowling deeply. Izuku’s blood was all over him and the floor… so much… way too much… but he kept pressing the soaked-through cloth against Izuku’s neck anyways.

“You know it’s hopeless!” Izuku was too weak to actually pull Katsuki’s hands away, but he kept trying.

“Shut. It.”

“It’ll be far easier to kill me now before—”

“Stop talking,” Katsuki ordered furiously, meeting Izuku’s eyes to bark the words at his face. “Stop talking right now!”

Izuku did not. “Give me the knife, Kacchan! I’ll do it myself!”

“We don’t even know if that’ll work!”

“It’s worth a shot!”

“NO!”

Izuku wheezed out ragged breaths. His skin that wasn’t covered in blood was way too pale.

“W-why?” Izuku’s voice was pleading again. “You’re going to let me bleed out? Become one of those things?”

Katsuki’s hands were shaking badly as he reached over his head, grabbed the back collar of his own shirt, and yanked it off. He balled it up and pressed it to the wound, tossing the soaked-through bandages and cloths to the side. His teeth were clenched, and his eyes were shiny with unshed tears.

“You’re not going to die.”

“Kacchan, you know I am,” Izuku said weakly. “So… give me the knife. If I don’t die from the wounds, maybe it’ll stop the transformation.”

Katsuki didn’t move. He was breathing hard enough that his chest heaved with each breath. He was covered in Izuku’s blood up to his elbows. More blood was splattered across his torso and pants. He was next to Izuku, leaning over him, and he was kneeling in a pool of blood. A tear dripped off his lashes in great contrast with the angry look twisted across his face.

“Once I’m gone, you need to set my body on fire,” Izuku whispered. “That should stop anything from happening.”

“SHUT UP!” Katsuki leaned closer. One hand cupped the opposite side of Izuku’s neck, the other still pressed to the wound that was still bleeding far too much. “DAMMIT!”

“Promise me.”

Katsuki didn’t reply.

“Kacchan, please promise me.”

“I—I can’t.” Katsuki’s voice wavered and broke abruptly. More tears trailed down his cheeks. “I can’t do it.”

“If you don’t, I’ll become one of those things!”

Katsuki just pressed harder against the wound. Izuku flinched, then coughed wetly. Blood stained his lips.

“What would you do?” Katsuki asked hoarsely, staring down into the wide, pained green eyes of his oldest friend. “If it was me who was bitten, what would you do? Would you really let me go? Let me die?”

“I’m going to die no matter what, Kacchan. It’s not your fault but there’s no sav—”

“If we let the transformation happen, you’ll still be alive.”

Izuku’s glassy eyes filled with horror. “W-what?”

Katsuki went on, voice growing firmer and more confident as the idea settled into his mind. “You’ll still be alive. You’ll be a vampire but you’ll still be alive.”

“No, no, no. I’ll be undead, Kacchan! That’s not the same at all!”

“Vampires are sentient and intelligent. It’s just… a different kind of living.”

Izuku gaped at him. “They drink blood!”

Katsuki hesitated, breathing hard and looking down at Izuku. His hands shook badly where they were still pressed to either side of Izuku’s neck, only slowing but not stopping the inevitable.

“I can’t do any of this without you,” he admitted brokenly, choking on the sob that spasmed in his chest. “You’re all I’ve got left. I can’t… you can’t…”

Izuku grimaced with pain and grief, tears streaming down his bloody cheeks. He squeezed his eyes shut. “I’m sorry, Kacchan. I’m so sorry.”

“What would you do, if you were me?” Katsuki asked again, gravely. “Would you let me die?”

“If you asked me to let you, then yes, I—”

“Don’t lie.” Katsuki cut him off sharply. “Look me in the eyes and be honest.”

Izuku’s eyes peeled open and he looked up at Katsuki. There was an incomprehensible grief and overwhelming desperation in both of their eyes. One heartbeat passed. Then another.

Something like understanding settled on Izuku’s face. Still, he said, “It’s too dangerous, Kacchan.”

“That’s not an answer.”

“We learned that when vampires first turn, they aren’t used to their thirst yet!”

“Give me an answer.” Katsuki leaned in closer, searching Izuku’s gaze. “Would you let me die, if it were me?”

Izuku’s voice broke. Again, he dodged a real response. “We don’t know enough about them. If you let this happen, I could hurt someone! I could hurt you!”

“I won’t let you.”

“I’ll have to drink blood to live.” Izuku tried to tighten his grip on Katsuki’s wrist, but it was slippery from all the blood and he was very weak. “It’s not an option for me not to. So you have to kill me now. Before anything happens!”

Katsuki hesitated again, then said, “I have blood.”

“What?”

“I have blood,” Katsuki repeated more firmly. “I’ll bring animals for you to drink from, too.”

“N-no, wait, wait,” Izuku said, aghast. “You—you can’t! I’ll—I’ll kill you!”

“You’ll stop before you kill me.”

“I might not be able to! We don’t know!”

“Then I’ll stop you!”

“You know that won’t work!” Izuku’s voice had gone shrill with desperation. “The venom will paralyze you!”

“It might not, some sources say it’ll only cause confusion and a daze.”

“That’s—that’s not good either!”

“Do you trust me?”

They stared at each other, both crying and conflicted and terrified.

“This has nothing to do with trust,” Izuku whispered. “It’s just too dangerous.”

“I’ll keep you contained until you calm down.” Katsuki spoke quickly as his mind spun with desperation and the light started to fade from Izuku’s eyes. “If I can’t handle it, I’ll kill you myself, Izuku. I swear it on my parents’ grave.”

Izuku’s eyelids fluttered. A few last tears trailed down his cheeks, disappearing into all that blood.

“If it were me, would you be able to let me go?” Katsuki asked one last time, eyes hardened.

“No.” The whisper tore from Izuku’s throat like a confession. He shuddered out a weak breath, then said, “Just swear to me that you won’t let me hurt anyone. I’ll never be able to forgive myself.”

“I swear it.”

“That includes you,” Izuku added brokenly. “Don’t let me hurt you, Kacchan. Please.”

“I won’t,” Katsuki vowed as determination settled into his veins.

For another moment, the two of them stared at each other. They were so far from the land they’d been born and raised in. The land they’d left ten years ago when their families had been among hundreds killed by invaders. The land they’d sworn to return to next summer to pay their respects.

They were many days from their current home, too, in the city of the royal family where they studied under some of the best warlocks and conjurers in the entire world. A city that’d finally begun to actually feel like a home so many years after they’d lost their first one.

In a cave high up in the mountains, where Katsuki had dragged them when the storm had made it impossible to keep going down the mountain, they stared at each other.

“You’re all I’ve got left,” Katsuki pleaded brokenly. “Let me try.”

“Okay,” Izuku murmured. “I trust you, Kacchan.”

His fingers squeezed around Katsuki’s wrist once. Then they went slack and his arm fell to the ground as the light finally faded from his eyes.

The feeling of panic and grief and anguish that immediately tore through Katsuki was almost too much to stand, but the determination that’d started to settle into him had flooded throughout his body. As the rest of it tried to paralyze him, his resolve forced him to move.

Still, he couldn’t fully stop the sobbing. He cried openly without witnesses as he worked. If he couldn’t stop the tears, then he would have to work through them.

Izuku had been right about their vampire knowledge. For as much as they had learned since moving to the city and starting their studies, knowledge on vampires wasn’t one of those things. From what Katsuki remembered, very little was known about them in general. All the legends and lore were sparse and incomplete, and it often contradicted itself.

Vampires drank blood. This was known in how they left their victims drained completely of blood. They were suspected to be incredibly fast, with various accounts of them being gone in the blink of an eye. They were strong as well. There weren’t very many accounts of people having survived a vampire attack.

They’d gotten lucky, all things considered. Despite how most lore described vampires as highly intelligent, this one had seemed almost rabid. It’d appeared without warning, biting directly into Izuku’s neck before either of them even knew it was there.

It’d attacked them right before dawn, and the sun had saved them. The sun had burned at its skin, weakening it enough for Katsuki to yank it off Izuku and ignite it with the strongest fire curse that he knew.

Of course, it’d been too late. It’d bitten deep into Izuku’s neck.

In the present, Katsuki’s hands were shaking as he yanked his pant leg up and snatched the small knife he kept there for emergencies. He sliced open his palm with a grunt, then moved his hand over Izuku’s mouth. He pulled open Izuku’s mouth, ignoring the nausea that lurched in his stomach, and let the blood drip onto Izuku’s tongue.

There was no time to hesitate and no time to think about how disgusting his actions were. There was no time to think about how if hell existed, he was likely condemning himself and Izuku to it. There was no time to think about any of it.

It was a massive, massive gamble. This was all a massive gamble based off limited knowledge stemming from limited, outdated source material. Some legends mentioned that if a vampire tasted human blood during the transformation, that they could form a strange sort of bond with the owner of the blood.

If that legend was true and not just a load of horseshit, then maybe Katsuki could help Izuku gain some level of control. While it could just mean that Izuku would just want to kill him faster and more aggressively… it could also mean that Izuku might not kill him.

What Izuku had said was true, after all. Many sources agreed that vampires that just turned weren’t in their right minds at all. They were mad with bloodlust and would tear their own friends and family to pieces if they came across them.

But… if that legend held any truth to it at all, then there was a chance that Izuku might instinctually not kill him. That despite how he was mad with bloodlust, he would stop before doing real damage to Katsuki. Instinct would tell him that if he just waited… the source was an endless well of highly desirable blood.

Katsuki felt nauseous as he stared down at the unmoving body of his oldest friend and his only remaining family. Izuku was too still, too silent, too pale, and too bloody. It was hard to comprehend the sight of him. Really, this felt like one horrific nightmare.

Katsuki squeezed his hand tighter, tensing from how the pain in his palm spiked. More blood dripped from the wound he’d created. Then, he closed Izuku’s mouth, hoping the blood would do what it was supposed to.

Katsuki wasn’t one of the most talented conjurers that the royal city had ever seen for nothing. He was a damn good warlock, and he was going to figure out a way to make this work if it was the last thing he did.

He would keep his oath to Izuku.

The sight of Izuku lying there, unmoving, was suddenly unbearable. Katsuki felt more than a little ill, more than a little exhausted, more than a little pained. Still, he had to move or he would completely lose it.

Katsuki’s hands shook as he tossed the bloodied cloths to the other side of the cave. It stunk badly in here. So badly. He would have to clean up the blood.

Right after he secured Izuku. He had no idea how long it would take for Izuku to turn, but it wasn’t an option for Izuku to wake up and attack him.

Katsuki got to work.

He’s not dead. He told himself over and over in order to move past the shock and grief from the sight of all the blood and the unmoving body of Izuku. He’s going to wake up.

They had no one but each other. Sure, by now they had other friends in the city of course, but…

Izuku was family. They’d known each other their entire lives, as long as either of them could remember. They’d had ups and many, many downs in their youth, but they’d grown close in recent years. So close that sometimes… sometimes Katsuki thought that…

Katsuki shoved all his swirling thoughts from his mind, trying to focus on formulating a plan. He’d have to contain Izuku until he calmed down from the initial bloodlust. He’d have to start drawing his own blood and preserving it, so that he didn’t weaken himself too much at once.

As he worked, every once in a while the shock and nausea would tear through him and almost send him to his knees.

He’s not dead. Katsuki repeated it over and over, forcing himself to move. He’s going to wake up.

He has to wake up.

Izuku

Izuku woke up thirsty.

His eyes flew open, grunting out a noise of pain as the burning in his throat grew more and more by the second. The feeling was so intense that for a moment, it was all he could focus on.

“Izuku, can you hear me?”

A voice echoed in his ears. It was very loud, but he didn’t process it in the slightest. All he could register was the agony in his throat, a dull pain, a dryness, a thirst that wiped his mind of all higher thoughts.

But a second later, there was a different sound. This one did register to Izuku.

Ba-dump. Ba-dump. Ba-dump.

A low thumping sound. A rhythmic beating. Izuku zeroed in on it, his senses focusing and hearing the thumping, then the sound of flowing, viscous liquid. Some instinct within him knew that would quench his thirst. That would stop the agony. That sound… that flowing liquid… he wanted it more than anything.

Izuku’s lips parted as an ache shot through his teeth, so intense that it radiated up into his skull.

“Izuku? Can you—”

Izuku was moving towards the sound before he realized what he was doing, but was immediately yanked to a halt. He tried again, only to again meet resistance. A snarling noise ripped from his mouth as it all grew unbearable. He tried to fight forward towards the thing that would help him.

“Shit! Izuku, can you hear me?! I tied you up and cast every containment and restraint spell that I know. Stop fighting it, Izuku. I’m going to help you, okay?”

The voice echoed in Izuku’s ears again. So annoying, how it diluted that beautiful rhythmic sound. Izuku wanted it gone.

Ba-dump. Ba-dump. Ba-dump.

Izuku snarled furiously again, enraged at being unable to move and how the voice was getting in the way of that wonderful sound. More noises ripped from his throat instinctively as his need for something to quench his thirst grew. It burned so bad that, if he’d been able to move his hands, he might’ve tried to tear out his own throat. As it was, his hands were pinned behind his back, and since he’d yanked forward and failed to move, he’d fallen to his knees.

He only grew more frenzied with each passing second, trying to yank himself free to no avail.

Ba-dump. Ba-dump. Ba-dump.

“Izuku… Izuku, please. It’s Kats—it’s Kacchan.” The voice wavered and broke so violently that Izuku stilled momentarily as some muted instinct of alarm shot through his body. It did little to break through the haze—like throwing a bucket of water on a housefire—but it did draw his attention away from his state of captivity and over towards the voice and that rhythmic sound.

Of course, the moment Izuku did, his vision tunneled and locked on the source of the sound.

Ba-dump. Ba-dump. Ba-dump.

A short distance in front of him. His prey’s neck was exposed. Under the surface of its skin, he could see the ticking of the liquid. He could hear it rushing in its veins.

Izuku panted quickly and loudly, less out of actual need for air and more out of some habitual reaction to his frustration and desperation. The ache in his teeth had spread up into his skull and down into his jawbone, mixing with the spreading pain from his throat and chest. He’d also begun to salivate so much that it was building up in his mouth.

“You can hear me, right? Fuck, I don’t…” The same voice from before echoed in his ears, muted further behind the sound of pounding blood. “Look, I’m going to give this to you, okay? Hopefully… hopefully this will be enough to quench the thirst for now.”

There was a small popping noise and then Izuku smelled it. His eyes ripped from his prey’s neck to find the source of the smell… the best thing he’d ever smelled… the thing that would quench his thirst…

It was a dark liquid being poured out of a waterskin into a small bowl.

Blood.

A sound tore from Izuku’s throat as he tried to throw himself towards it but was again stopped short. He snarled, pulling with all his strength, snapping his teeth threateningly. His mind had long abandoned him for instinct as he fought forward, making noises somewhere between distressed and threatening and anguished. Drool escaped his lips, and he gnashed his teeth more as the ache in them grew unbearable. Unable to tear out his own throat or teeth or find respite from his agony in any way, he ground his teeth together in between snarls and growls.

“Fuck! Calm down!” The voice snapped. “I’m giving it to you!”

Then the bowl was hovering closer to him in the air, then set on the floor right before him. Izuku’s mind went blank as he dove down for the blood. With his hands still secured behind his back, his only option was to duck his head down to reach the bowl with his face. His mouth opened as he all but dunked his chin under and let it flood his tongue. He started to gulp it down desperately, groaning low in his throat with pleasure as the taste… oh god the taste of it… flooded his tongue.

At first, it was like a salve on a burn. A cool cloth on eyelids puffy from crying. A fire to cold hands. It was an instant relief.

Within seconds, it became much more than that. Once the most immediate pain was soothed, Izuku began to shake all over. He gulped down more desperately as his whole body came alive. Warmth, strength, pleasure, and a deep satisfaction were spreading through him more and more by the second.

Before he knew it, he was licking desperately at the bowl. He was panting hard and letting out low, clipped grunts and groans of satisfaction and pleasure as the high rushed through his system.

Izuku’s teeth still ached so bad that a dull pain was radiating throughout his gums. Still, his throat was no longer completely dry. His head was a bit clearer. He felt a bit calmer. He wanted more of that blood. He needed it more than anything, but he was no longer in a completely frenzied state.

He could perceive his surroundings more clearly now. He could feel the ropes tying his hands together by the wrists behind his back. He could feel the strength of the magic simmering in the air around him, keeping him from moving too far forward or ripping the ropes off. He could perceive the spacious cave they were in, and most of all he could sense…

Izuku’s eyes jerked up and again locked in on his prey. Instinct told him to meet his prey’s eyes, but his prey’s eyes were averted.

“Izuku, can you hear me? Can you understand me?”

Ah, the voice was coming from his prey. His prey was speaking. At least he could stop that annoying voice and indulge in his meal at the same time once he got free of these restraints.

Izuku stared, waiting for his prey to look at him. Just once was all he needed, and then he could lure his prey over here. He knew instinctually that this was an inferior being. Its mind wouldn’t be able to put up a fight against Izuku’s power.

Izuku’s thoughts were clear enough now. They were single-mindedly focused on getting more of that blood. He knew with certainty that what he’d just tasted was running through his prey’s veins right now. He could smell his prey from here, and it belonged to the taste that still lingered on his tongue.

He needed more of it.

He stared at his prey’s neck. He could see the ticking pulse of the blood underneath. It was hard to look at anything else, especially because his prey so cleverly kept its eyes downcast.

But his mind had cleared enough to think the slightest bit more logically. His prey was clearly smart enough. It had restrained him effectively. It was speaking to him. It knew to stay far away and not look him in the eye. It might be a weak minded and weak bodied creature, but it seemed to be smart enough to know that much, at the very least.

But it couldn’t be that smart, seeing as it wasn’t running away. Was it the thing that had restrained him? Why would it do that and feed him? What was its end goal?

Izuku would have to rise to the challenge if he wanted more of that blood.

“Dammit, answer me if you understand me at all!” His prey shouted, and its voice cracked at the end.

“I can understand you,” Izuku replied evenly.

Izuku’s unblinking eyes caught how his prey jolted at the sound of his voice and how its eyes darted closer to looking at him, but not all the way.

“Fuck.” His prey breathed out shakily.

Ba-dump. Ba-dump. Ba-dump.

Izuku could hear how his prey’s blood pumped even faster. His teeth ached to sink into its neck. He started to pull harder at the restraints on his wrists. He felt the magic fighting him, and he fought back.

“Do you… do you know who I am?” His prey asked hesitantly. “Do you recognize me?”

“I’m thirsty,” Izuku said, rather than answer his prey’s silly, pointless questions. “Do you have any more of that?”

He jerked his head down in the direction of the empty bowl. He ran his tongue around his mouth and over his teeth and lips to try and gather any remaining blood. In his haste, he knew some of it had spilled down his own neck and torso. He regretted not going slower now… not that he’d been able to think straight at the time.

“Yes,” his prey said in a stilted tone. “But you’re gonna have to work with me here.”

Izuku felt a flare of mind-numbing rage roll through him at the extended conversation. His thirst was building again by the second, and it was making it harder to think. Even if he wanted to play his prey’s silly games, he soon would be in too much agony to do so. He strained harder against the magically reinforced ropes.

“It’s yours, isn’t it?” Izuku asked as his lips stretched into a wide, manic grin putting his bloody teeth and elongated canines on display. “I can smell you from here.”

“Yeah, it’s mine. And if you want more then you’ll answer my questions.”

“I’ve got a better idea,” Izuku replied, already panting harder as the sound of his prey’s blood grew louder and rushed faster in his ears. “When I break out of these ropes, I’ll take it from the source for myself.”

His prey jolted, and its eyes almost met Izuku’s again.

“You’re not breaking out of there,” his prey said sharply. “You’re secured with nearly a dozen enchantments. You’ll rot in that corner for all eternity before you break them.”

Izuku let out a half-screamed of frustration through his teeth as his thirst demanded more from him. He could feel the strength of the magic, almost heavy on his skin. It was so potent that it was practically weighing him down.

He was being taunted. By his own fucking food. What the hell was this?

Izuku’s rage and thirst mounted as he pulled at the restraints. He was again losing his head to instinct. Was he really going to be left to starve here if he didn’t do as this thing wished? Could he really not break through this weakling’s enchantments? He could sense this creatures weakness from here.

Ba-dump. Ba-dump. Ba-dump.

What a joke this was. A mockery.

“I’ll kill you,” Izuku snarled. “You think you can lock me up and starve me? I’ll break out of here eventually, and I’ll find you. There’s nowhere you can run where I won’t find you.”

“What?!” His prey’s voice went shrill with shock. “I’m not starving you, idiot, I’m just—”

“You are,” Izuku cut him off, nearly half out of his mind with rage now. “Is this fun for you?! Do you feel powerful, you weakling?!”

“Shit… hold on, this isn’t… goddammit.” His prey sounded frustrated, but its voice was again fading in Izuku’s ears.

Ba-dump. Ba-dump. Ba-dump.

Izuku screamed in rage, thrashing as he tried to free himself. He threw himself forward wildly.

“Fucking hell, calm down! I’m getting it, okay?! Stop doing that!”

Izuku didn’t comprehend the annoying voice anymore. He snarled and spat and screamed as he yanked harder. Like hell would he let himself go mad here. Like hell would he—

His mind was again wiped clean as he smelled more blood. His eyes shot over find it. The bowl was back over by his prey now, and blood was being poured into it.

Before long, Izuku was drinking up more of the blood.

They did this several more times, with the prey taking the bowl back and adding more blood to it. His prey was talented with magic. It was able to move the bowl with magic so it didn’t have to approach him at all.

Even as he consumed more blood and was able to calm down again, a part of Izuku was still furious. He wanted to sink his teeth into his prey, and being tied up like this was infuriating.

But the moment the blood was within reach, it was all he could focus on. So much so that he couldn’t focus on trying to get out of his restraints.

By the time the blood seemingly ran dry—or at least, Izuku was no longer being given blood—he felt good. So good. His head felt light in a very pleasant way. He didn’t feel nearly as thirsty as before.

Izuku sat back, leaning against the wall and letting out a low, satisfied groan as he floated. The taste of the blood stuck around on his tongue and teeth, and he sucked on them happily as he enjoyed the feeling that lingered from drinking the blood.

It felt like his entire being was light, floating, tingling with pleasure. He felt strong, sated, rested, at peace. Yes, he could easily drink way more and yes, his teeth still ached, but he felt so much better than before. Truly, he felt so good that he just wanted to sit there and revel in it.

He did so… until a scuffling noise caught his attention and his eyes flew open.

Izuku peeled open his eyes to see his prey—

No, wait…

He squinted through his tunnel vision, trying to look away from where his gaze instinctually was drawn to the creature’s neck.

A human. That’s what it was called.

Chapter Text

Izuku

It was a male human, to be specific.

A male human with spiky pale blond hair. From this distance, it wasn’t easy to tell just how tall it—he—was. Its—his—linen clothes were loose, with dark brown pants tucked into faded leather boots. With the sleeves of his light gray shirt pushed up to his elbows, Izuku could see muscular forearms and—far more excitingly—the blue veins running under the skin of his wrists and forearms.

Though he was still avoiding eye contact, Izuku could see that his eyes were blood red. Izuku liked them. He wished the human would actually look at him with those eyes, so that he could take control of his weak mind and get himself out of here. But the human’s gaze remained averted.

Izuku stared as the human crouched before a small fire on the other end of the cave, stoking it. He could hear the human’s breathing… he could hear his pulse ticking away. He could smell him, and the taste of his blood lingered in his mouth.

Izuku’s vision zoned in on his neck, where he could see the blood flowing underneath. His mouth started to salivate again. His teeth still ached, completely unsatisfied by the lack of biting done before consuming the blood.

But Izuku also stared because there was a weird feeling growing in his gut. Now that he wasn’t consumed by thirst, he got the sense that he’d seen this particular human before. He didn’t remember much of anything in general, only vague places and feelings. Still, this human was oddly familiar.

The human shifted, moving to stand, and Izuku followed him with his eyes.

“I know you’re staring at me,” the human said out of nowhere as he crossed over to some bags propped up against the cave wall. “I can feel your eyes on me. It’s creeping me out.”

“So you do have survival instincts,” Izuku said, eyes still locked on the human. “Yet you’re in here with me. Keeping me captive instead of running for your life.”

“Yup,” the human said, unamused. “Do you recognize me yet?”

Izuku was surprised by the question, though he wasn’t sure why. Maybe because this human was familiar, but he couldn’t remember in what way. Was he simply attempting to recall when this human had taken him captive, or had he encountered him before that?

Clearly the human remembered him.

“Your blood tastes very nice.”

The human made a snorting noise that Izuku realized was some kind of laugh.

“It better,” he said. “It’s the only human blood you’re ever going to get.”

That made Izuku’s attention zone in on him—rather than his blood—more fully. “You’re going to give me more then?”

The human was silent for a long moment. “Yes.”

Izuku shifted until he was on his knees again, shuffling forward to again test his restraints. They held tight… for now.

“What is it that you want from me?” Izuku asked, swallowing the spit gathering in his mouth as his gaze again locked on the neck of the human. He sucked on his teeth again, running his tongue around his mouth as he again searched for any last bit of that delicious blood. “Why do you have me tied up here?”

“If you remember me, then you’ll figure it out.”

Izuku let out a growling, frustrated noise. His words sharpened as his frustration spiked again. “Let me bite you, human.”

“Hah? Why the hell would I do that? You know, you threatened to kill me not that long ago.”

“You seem fine with giving me your blood,” Izuku said. Hopefully reason could work on his inferior creature. “You plan on keeping me captive and giving it to me anyways. So just let me bite you, and we’ll both get what we want.”

The human stilled. His gaze trailed across the floor, again approaching Izuku but never getting too close to meeting his eyes.

“What does that mean?”

“If you want me to know who you are, then let me bite you. I’ll be able to tell who you are then.”

The human remained very still. “How?”

“Your blood… what you already gave me… I can taste everything. If you let me drink from the source, I’ll be able to read your mind. Your memories, too.”

“But you couldn’t just now?”

“Not quite, but I can tell that you’re very sad. I can taste a deep loneliness and fear within you. It sours the taste a bit. I can also tell that you harvested some of this blood many hours ago, and some of it much more recently. If you let me drink right from your bloodstream, I can sense so much more.”

The human hung his head. Izuku couldn’t see his face, only the top of his head as his hair hung down in his face. He could hear his shaky inhales and exhales. The anxious, terrified, erratic beating of his heart. The sound of it exhilarated Izuku to no end.

The human replied in a tense, almost annoyed tone, “That’s a nice try, but I can’t afford to let you anywhere near me. You’ll kill me.”

“Kill you?” Izuku licked over the front of his teeth again. “No… I just want a taste.”

“Ha! Right, sure. You do remember that you told me you wanted to kill me, right?”

“I was just thirsty. I’m telling you now that I won’t. If you die, I won’t get any more of your blood. You can trust me.”

The human didn’t reply except to let out a half-hearted scoff, shaking his head slightly.

Izuku stared at the human. His aching teeth were more than a little bothersome, and he clenched his teeth together and unclenched them in an effort to ease up some of the pain. Or to distract himself from it somehow.

He was still pissed off, but even more so he was confused. What was the purpose of all this? What did the human want?

“I tasted your fear just as intensely as I tasted your grief,” Izuku said. “Even if it doesn’t show on your face, I can taste how terrified you are. I can hear how your heart races.”

The human’s breath hitched momentarily, before he forced out a long, slow breath.

Izuku went on, “Why’re you keeping me here, when you’re clearly so scared of me? Why ignore your survival instincts? What is your end goal?”

The human scoffed loudly this time, and only offered in reply, “I’m not scared of you.”

“Then what are you scared of?”

“Just… just that I made the wrong decision.”

Izuku was annoyed. That was vague. Unhelpful.

He watched the blood moving under the skin of the human’s neck for a while. It was driving him halfway insane. He grinded his teeth together, listening to the flow of blood and the pumping of the human’s heart.

If you remember me, then you’ll figure it out.

The human intended to wait until Izuku remembered him? But Izuku didn’t remember anything, so why would he suddenly know who this human was?

Izuku was growing more desperate as the minutes ticked by. He watched the human work on whatever human stuff he was doing. Tending the fire, skinning some rabbits, sharpening knives, drying herbs.

Well, Izuku watched the human’s neck for most of it, but he was also vaguely aware of what the human was doing.

“Let’s make a deal,” Izuku said abruptly when the sun had sunk under the horizon. In the darkness of the cave, the firelight cast everything in flickering, orange hues.

The human didn’t so much as pause in his stirring of something in the pot over the fire. He didn’t reply.

Izuku went on. “You seem fine giving me your blood. Let me out of this now, and I won’t kill you. I’ll know who you are from drinking your blood, and I’ll only take some of it. You’ll live. I can make it so you won’t even notice what I took, either. Just let me have more, I’ll remember you and I’ll let you live.”

The human stirred the pot. He looked stoic, and it took him a minute before he replied, “I already said I was going to give you more.”

“From the source.”

“No. And even if I wanted to give you more right now, I can’t. I can only give so much without making myself unwell.”

“I told you, if you let me bite you, I can make it so you won’t feel unwell.”

“You already tried convincing me of this. It’s not going to work. I’m not letting you out, and I’m not letting you bite me. I know you’ll kill me, and I can’t let you do that.”

Izuku resisted making a noise of frustration, instead clenching his teeth together hard enough to send the ache spiking into something sharper that radiated further up into his gums. When he unclenched them, the typical ache felt less bad in comparison.

His mind raced, trying to think. How could he convince this human when he didn’t know what exactly it was that he wanted in the first place?

It was also so difficult to think with the constant sound of the human’s heart beating and blood rushing in his ears. With the human’s smell filling the cave. With the sight of the veins on the human’s neck and wrists right in front of him.

The minutes started to tick past again. The human ate whatever was over the fire. Izuku stared at his neck, salivating more and more.

“It’ll feel good, you know.” Izuku’s voice came out deep and intense as he stared at a vein on the human’s neck. His mouth was watering with the memory of the blood, and his thirst was slowly but steadily becoming overwhelming again.

The human visibly stiffened, red eyes trailing most of the way across the cave towards Izuku. “What did you say?”

“I can make it feel good,” Izuku bargained, spurred on by the uptick in heartrate. “As I drink it, it’ll feel good for you.”

The human’s mouth gaped. He looked a bit baffled. Maybe horrified. “You can make it feel good as you kill me?”

“I just said I’m not going to kill you!”

“Yeah, well, I’m sure you can understand why I don’t believe you.”

Izuku again reached the end of his limited patience.

“What’s your plan here, human?” Izuku snarled, baring his aching teeth. “Are you going to keep me captive here for the rest of your life? Your magic won’t hold forever!”

“It will if I renew the enchantments.”

“Tell me why!” Izuku demanded, half shouting as the sound of blood and heart taunted him and his fury consumed him. The idea of enduring this forever was an intolerable one. “Why do you intend to keep me captive? To treat me like an animal? Keeping me tied up, feeding me from a bowl while my hands are tied—”

“I don’t want to do that, but you’ll kill me if I fuck this up!” The human’s voice was abruptly very loud and angry, but there was something else underneath the surface. Something sadder. More desperate.

“Then tell me why! I don’t even know what you want from me! Why are you torturing me like this?!”

“Torturing you?!”

“Yes! You’re standing near the entrance to this stupid cave, and each gust of wind funneling through here brings your scent to me even more. I can hear the blood rushing in your veins. I can see it beating under your skin. But you only give me some of your blood and won’t even let me bite you—”

“I’m trying to save you!” The human shouted, shoving to his feet. His hands were balled into fists at his sides. “I’m trying to fix this, okay?! Goddammit, Izuku!”

The human suddenly turned away from him, his palms coming up to slam over his eyes.

Izuku stared in complete fascination. The human was crying. He was trying to pretend he wasn’t, but Izuku could hear his stuttered breaths. He could smell the salt of his tears, and he wanted to lick them off his cheeks.

He didn’t understand what was going on at all.

“You keep calling me that.”

“Calling you what?”

“‘Izuku.’ You keep calling me that.”

The human paused for a long moment. Then quietly, in a stilted tone, he said, “That’s your name. You don’t remember it?”

Izuku stared at him. It felt right, that that should be his name. It sounded familiar in his ears, even if he couldn’t exactly remember it being his name. As if he could’ve picked out which name was his off a list, even if he couldn’t recall it all on his own.

But how did the human know his name?

“I remember nothing.”

The human didn’t reply. He remained with his back turned, hands scrubbing over his eyes and face somewhat aggressively.

“I’m not sure why you think keeping me captive here is ‘saving’ me, but I assure you it’s not,” Izuku eventually said. “But—”

“I swore an oath, okay?” The human’s voice came out sharp. Aggressive.

“An oath to who? About what?”

The human ignored the first question to answer the second. “That I wouldn’t let you hurt anyone. That I wouldn’t let you kill anyone.”

Izuku stared at the back of the human’s neck, completely baffled. What the hell? An oath to not let him hurt anyone… but not to kill him? He knew it was likely within the human’s capabilities to kill him, if the human was skilled enough to restrain him like this. And yet, he was trying to “save” him rather than kill him?

Was killing him not the quickest way to not let him hurt anyone? Not that Izuku intended to remind him of that particular fact, but he was still bemused.

Did the human not fully understand what Izuku was? Did he not understand that it was in Izuku’s nature to consume his kind for sustenance?

But Izuku wasn’t a monster. He’d noticed how the human had cleanly snapped the necks of the rabbits he brought back. It was no different than that. Izuku might know humans were inferior and weak, but he recognized their intelligence. He would kill them quickly. Painlessly.

It was just the food chain. The natural way of things.

His lips parted, intending to explain this to the human, but he paused. His eyes trailed down to the pot in which the human had cooked the rabbits into a stew. Somehow, he doubted the human had explained to the rabbits the why or how before he’d killed them. And what difference would it make if he had? The rabbits wouldn’t have rolled over and just let him do it.

The human wanted something impossible from him.

If Izuku were to live, he’d have to eat. This human seemed to not fully understand his nature, and Izuku doubted explaining the whys or hows to him would change his mind. The human was insane. Or stupid. Or uninformed. Or secretly did get a power trip out of keeping a far superior and more powerful trapped like this.

It was as if that rabbit had the human restrained in a corner, feeding him only the bare minimum to keep him away from the brink of starvation.

The laws of nature were askew in this damn cave. The food chain had been broken apart by this egotistical, foolish human.

As Izuku watched the human lie down on the far side of the cave, putting his head on one of the bags and lying on a makeshift bed of thin blankets and clothing, Izuku dug his canines into the inside of his own bottom lip. The sharp pain that spiked out and the blood that flooded his mouth did very little in the end. It offered only momentary relief to the ache of his teeth as his body immediately realized that it wasn’t biting into anything useful.

He pulled his teeth free, and his wound closed immediately. He swallowed his own blood, instantly regretting his decision. His own blood had washed away the taste of the human’s that’d lingered so faintly. It was gone completely now, and he was left to slowly go mad as he listened to the heartbeat of the human eventually even out and slow with sleep.

Ba-dump. Ba-dump. Ba-dump.

Izuku got the feeling that he wouldn’t be set free anytime soon. He’d have to break himself free. He’d have to wait for the human to slip up and look at him.

He’d just have to wait and watch.

Katsuki

Days passed.

It hadn’t taken Katsuki long to figure out that the lore he’d learned of previously was largely incomplete.

The main issue was that he hadn’t known that vampires apparently didn’t remember their human lives. It made sense, in the end. The lore said that vampires that’d first turned were so mad with bloodlust that they’d tear apart their own friends and family. It made a lot of sense that this was helped along by the idea that they also didn’t recall at all that those people were ones they’d once loved.

Katsuki had originally assumed that Izuku didn’t recognize him through the bloodlust. But Izuku had calmed down and still had no idea who Katsuki was. He’d threatened to kill him, which was so completely un-Izuku-like that Katsuki had felt sick.

So… It was all so much more unsettling than Katsuki had prepared himself for. Because Izuku looked like Izuku, but he really didn’t feel like Izuku. His voice was slightly different sometimes too, in a way Katsuki couldn’t always put his finger on. His skin was paler. His hair the same, his body looked the same from the outside…

Katsuki hadn’t dared to look at his eyes. Most legends warned of how vampires could control you if you made eye contact. Looking into Izuku’s eyes would be a death sentence.

It was similar with his name. Some legends said vampires could influence you much more with your name. Even if the legends hadn’t said that, Katsuki was a warlock. He knew the power of a name.

So Katsuki never offered it. He didn’t even tell him about “Kacchan” even though it was just a nickname. It felt wrong, and the idea of this version of Izuku calling him that made him feel almost more unsettled than if he just gave the vampire his real name.

Izuku just called him “human” or—even more disturbingly when he grew thirstier—he called him “prey” or “weakling” or something equally weird. The first time he’d called him the former was so deeply unsettling that Katsuki had to leave the cave and go panic and dry heave near the closest waterfall until he could get himself to calm down. Comforted in that the loud rushing of the waterfall would drown out any noise he made and allow him to lose it in peace.

Besides the occasional overwhelming panic in the beginning, Katsuki didn’t have the time nor the energy to really stop and think about if he’d made the wrong decision. Maybe his brain had been broken by the mere idea of the immense grief of having to watch Izuku die, but he couldn’t yet find it in himself to regret what he’d done.

Izuku often insisted that he could taste the misery in his blood—and the bastard would sometimes complain about it—but Katsuki knew that he was far better off than if Izuku hadn’t woken up that day. As uncertain and arguably hopeless as this all was, Katsuki couldn’t seem to get rid of the hope that Izuku was in there somewhere. That something would restore his memories.

Or maybe it was just the only thing still keeping him going.

Maybe the immense grief loomed as a threat in the back of his mind, apparently enough to still poison his damn blood. Maybe he genuinely didn’t know how to survive such a thing, so he kept running from it.

He could only cling to his hope and wait for the moment that Izuku would cross some threshold and act more like himself.

Another issue that quickly became clear came from the fact that Katsuki was a terrible hunter. He’d never had to be a good hunter. In the town he’d grown up in, his parents were tailors. He knew how to set traps from having learned later in life, but he was no good with distance weapons. The bow and arrows he had with him now had been Izuku’s.

So, acquiring animal blood had been easier said than done. Rabbits offered very little, and it was too congealed by the time he found them dead in the traps he’d set anyways.

Katsuki was forced to only give Izuku his own blood, for lack of a better option.

He’d go down by the river, downwind of the cave, and slice open his arm or palm. He didn’t dare open any wounds near Izuku. He didn’t want to know if that would throw Izuku into a frenzy again. Few things had been as alarming as watching Izuku screaming animalistically, seemingly willing to pull his own body apart to break out. Katsuki wanted to avoid that if possible. It didn’t matter if Izuku could heal well or quickly. He didn’t want Izuku to hurt himself.

Katsuki would gather the blood, having crafted a small funnel to get it into the waterskins, then he preserved it with magic. Luckily, warlocks often worked with blood. At least, he knew how to do this with ease. Then, he’d heal the small incision he’d made on his skin with a spell for minor cuts before returning to the cave.

But while Katsuki had intentionally been trying to form a bond between them by offering his own blood, it probably wasn’t a good idea to give Izuku only his blood.

Plus, Izuku often complained about wanting more blood, and it was hard to know if he was being dramatic or not. He seemed perfectly fine, he would just complain or ask for more. Either way, Katsuki physically couldn’t afford to give more than he was, so he had to figure out how to hunt better.

Katsuki slowly started to figure out how to handle things.

Katsuki set up camp within the cave. It was spacious enough, in a protected area of the mountain. Moving Izuku felt like far too dangerous and risky a move, so he didn’t even try it. Not yet.

The city that they now called home and their new life and friends would have to wait. If he tried to rush back to it, he might never get it back at all. And that wasn’t an option. Occasionally, he thought of their friends and colleagues in the city, who would likely be wondering soon why they’d not returned home from their quest north at the expected time. After all, they’d only been on a quest to search for a few rather rare ingredients. They were expected back within the month.

They wouldn’t be back within the month, of course. And Katsuki tried not to think about it too much. He considered trying to draft a letter and find a way to get it sent home but quickly put the thought from his mind.

Katsuki didn’t yet know if he would figure this out. Even if he did, vampires were hardly accepted magical beings. They were an isolated species that rarely interacted with anyone that wasn’t their own kind. He didn’t know yet whether or not it would be demanded that Izuku be killed if anyone found out he’d been turned into one, and he wasn’t willing to risk that. He’d cross all those bridges when he got to them.

In the cave they were currently calling home, Katsuki had long scrubbed away human-Izuku’s blood. He’d fashioned the makeshift bed and firepit for himself near the mouth of the cave. He’d gotten in the habit of making trips to the nearby river for water, making his rounds to check the traps he’d set, and going to gather firewood from the woods.

Of course, he’d placed every possible protection, detection, and occlusion ward that he knew.

While his space was near the mouth of the cave, Izuku’s was in the back. The cave ultimately wasn’t that big and only had one exit and entrance. Katsuki felt better where he was, for a lot of reasons. There, he could better protect Izuku and theoretically have a better chance of escaping him. There he also had a better chance of protecting others from Izuku.

Whatever happened… Katsuki would stand in between Izuku and the rest of the world. Whether to be the first to die for him or by his hand.

One thing that made Katsuki’s life way easier was when he figured out how to knock Izuku out. Though Izuku snarled and snapped at and threatened him during the first attempts, eventually he knocked him out with a spell that would’ve killed a human. Since it was a spell meant to stop vital bodily functions—brain, heart, lungs—it seemed to only put Izuku in an unconscious state.

Katsuki had been incredibly nervous to try it but reminded himself that vampires were notoriously difficult to kill. As he suspected, the moment he released the enchantment, Izuku woke up immediately.

Still, Katsuki didn’t like using it. And definitely not for prolonged periods of time. He wasn’t willing to push it.

He’d fashioned a bed for Izuku as well, though he had yet to see the vampire sleep. Most of the time, he had to keep Izuku’s hands tied behind his back until he was certain that Izuku remembered none of the magic from his human days. Most conjuring involved movement of the hands, and Izuku had also been a damn good warlock. Not to mention, maybe vampires could have magic of their own.

It was another risk Katsuki wasn’t willing to take. He rarely let Izuku’s hands be tied in front of him, and even less frequently did he allow them to be free. He’d checked on him the first few days after all, and Izuku’s skin was untouched. He was physically unaffected by the imprisonment, and thus Katsuki felt it was necessary for his own safety.

As the days passed, Katsuki quickly found the vampire to be a very strange and increasingly disconcerting creature.

Izuku never had to relieve himself or seem to require movement in any way. He didn’t seem to grow tired of sitting perfectly still or complain of really anything except a desire for more blood.

Katsuki cleaned Izuku’s clothes and swapped them out, allowing him freedom of movement for brief, supervised periods of time to let him change them. But it didn’t take Katsuki long to notice that Izuku didn’t seem to need to bathe either. He didn’t smell, and his clothes smelled only of dust and the cave. He didn’t ask to bathe either.

Izuku only ever asked for more blood. He only ever bargained for more blood. He only ever seemed to care at all about blood and getting more of it. At least this fit with the lore of vampires. Izuku definitely really liked blood.

Despite how Katsuki had tried to give Izuku places to sit or lie down, he most often kneeled or sat on the stone floor as he stared at Katsuki. Or sat back and leaned against the wall as he stared at Katsuki. He didn’t seem all that interested in comfort. Or sleeping. Or really anything at all besides staring at Katsuki—usually his neck, specifically—in the most unsettling way possible.

As intelligent and “normal” as Izuku seemed most of the time, there was an icy feeling that never left Katsuki’s spine. An instinctual fear that appeared whenever Izuku looked at him—which was practically every second that he was within Izuku’s field of vision. He could feel how deeply Izuku craved his blood, and it was impossible to trust. It was impossible to relax, as everything in Katsuki was constantly screaming danger, danger, danger!

Izuku tried to bargain with him over and over. He tried to insist that he wouldn’t kill Katsuki, that he’d make him feel good, that he only wanted a taste. He tried to bargain, to ask questions, to reason with him.

Katsuki couldn’t yield. He couldn’t trust a damn word out of Izuku’s mouth when he was like this. Izuku’s deep, alluring, sometimes borderline sensual voice… he couldn’t trust it at all.

Not to mention that Izuku would still occasionally grow furious and rageful, usually when he hadn’t had anything to drink in a while. He would immediately switch back to threatening Katsuki. Telling him he’d kill him. Tear him apart. Make him suffer for keeping him here like this and doing this to him.

The words sounded so wrong coming out of Izuku’s mouth. In Izuku’s voice.

Depending on the day, Katsuki just had to suppress the urge to shiver or vomit or cry. He would just have to remind himself that he was grateful to hear Izuku’s voice at all.

Weeks passed.

At least once a week, Katsuki loaded Izuku up with enough containment spells that they would’ve crushed or suffocated a weaker being. Then he’d trek to the nearest town, down the mountain and across the valley. It took several hours—and leaving Izuku for such an extended period of time had been nearly panic-inducing the first few times he’d done it—but Katsuki got faster at it as time went on.

Even on the days when he didn’t go, he’d spend several hours running up and down the mountain over and over, trying to push his own physical limits. And any time without Izuku’s eyes on him was a nice relief.

In town, Katsuki would gather books on vampires, on hunting, and on memory magic. He talked to the townspeople and made conversation with the frequent travelers coming through the mountains. He sought information that might’ve never made it to the books, or that lay written in books he’d never been able to get his hands on.

This situation might be a lot worse than he’d realized it was going to be, but he was nothing if not a man ready to rise to a challenge. In his weakest moments, he’d think of Izuku—human Izuku, his Izuku—and how if their roles were reversed, Izuku would find a way. Izuku had been stubborn like that. Nothing could stand in his way once he’d set his mind on something.

So Katsuki carried on.

Katsuki talked to Izuku a lot. He was certain that he talked to him now more than he’d ever talked in his life in general. He told him of their lives, of their childhood homes, of their dreams and ambitions, and of their current home that sat gathering dust in a faraway city.

Katsuki spoke of the stories of their lives as if human Izuku had been a different person entirely from the one he was speaking to. He referred to him with the mean childhood nickname he’d used to make fun of him in their complicated youth once upon a time.

Deku.

Of course, Katsuki could always feel Izuku’s eyes on him like a near physical thing. A terrifying thing. As he talked, he knew Izuku was watching him the entire time even without looking at him.

He was certain that Izuku listened to it all, because every once in a while, he would say something that indicated he had. Still, even then, it was so obviously different than what the human Izuku would’ve done. While human-Izuku would’ve listened because he cared, Katsuki got the sense now that Izuku was scheming. He didn’t care. He wasn’t interested. He was just listening, biding his time, trying to find some crack he could exploit in order to get what it was that he actually wanted.

Telling him of their lives was perhaps a fruitless attempt, but it was an attempt to jog Izuku’s memory all the same. It never seemed to work. There was never any recognition from Izuku or acknowledgement that he knew that he was Deku.

Katsuki could never bring himself to just tell Izuku that he was Deku. He couldn’t bring himself to tell Izuku that he was his oldest and best friend and that’s why he wouldn’t let him go or kill him or break his oath.

It felt like a line Katsuki couldn’t handle crossing on his own. This version of Izuku seemed interested exclusively in escaping and drinking Katsuki’s blood. When he got angry, he got mean and cruel and said things Deku never would’ve said.

Katsuki wasn’t sure if he could handle listening to Izuku cast aside his own humanity. Or handle Izuku trying to use it to manipulate him. If he told Izuku that he was the one in the stories, what if Izuku just pretended that he’d recalled his memories in order to get him to let his guard down? He wasn’t sure how far this Izuku would go to get free and get more blood, but he was sure he wouldn’t like to find out.

No… he needed Izuku to figure it out on his own. To remember. Or he needed to find some spell that worked.

So, Katsuki talked.

Izuku listened, staring at him all the while.

Katsuki had picked up the habit of rubbing at his neck. He caught himself doing it sometimes. He subconsciously would rub at where the skin tingled over his veins. He was certain it did so because Izuku was staring at that spot so intensely.

Doubt would creep in often as the weeks passed. He would hear Deku’s voice, begging him to kill him. He would stew in his fear, his longing, his loneliness, and wonder if it really was better if he killed them both.

But he would put it from his mind.

And carry on.

Months passed.

Katsuki got better with a bow, but not enough. Still, he kept trying.

He ran up and down the mountain with increasing ease. He practiced his magic. He read. He talked to Izuku.

He tried memory spells on Izuku, none of which seemed to have any effect. Izuku often grew angry as he did it, demanding to know what he was doing. While Izuku had undoubtedly grown far more docile over time, he still seemed to grow angry at the reminder of his own captivity and helplessness, which Katsuki supposed was fair.

When Katsuki told him he was trying to restore his memory, Izuku would just tell him to let him bite him. Over and over, Izuku told him that would fix things. Katsuki had no idea if it was true, but he couldn’t risk it.

The one singular time Katsuki had forgotten to renew the containment spells in a sleep-deprived moment of almost fatal idiocy, Izuku had nearly broken free.

Izuku had broken the iron shackles around his wrists—that Katsuki had bought from a blacksmith after spending an entire month saving for by trading remedies and potions he’d brewed—with his bare hands. When the enchantments keeping him in the corner of the cave hadn’t all given away, he’d started to tear through the stone floor and walls with his bare hands.

Katsuki had returned from his rounds and panicked. He’d knocked Izuku out immediately. When Izuku woke up, back in the shackles and fully contained, he’d grown more manically angry than he had in months. Katsuki tried to forget that day ever happened, if only because he’d never heard Izuku say most of those words in his entire life and those threats had been particularly disturbing.

Izuku’s strength now was no joke. His bloodlust hadn’t lessened at all, if Katsuki’s instincts were to be trusted.

Katsuki wasn’t taking any risks. Not a singular one.

Izuku would kill him if he broke free. Katsuki was certain of it. He wasn’t egotistical enough to think that he would have any chance of fighting Izuku off if he got free. He couldn’t risk even going near Izuku while he was conscious.

From all Katsuki’s studies and questions to travelers, there was never any record of anyone ever containing a vampire in this way. They were too fast and strong. Too elusive. Too clever.

The one story he’d found of someone who’d tried to contain one had ended with the man both drained of blood and torn in very many pieces. The author of the book was also a religious man and had called him an arrogant fool for thinking himself powerful enough to contain a creature that was descended from a demon of gluttony.

Katsuki was not a religious man himself, but after spending so much time with a vampire that seemed so single-mindedly set on consuming his blood, he understood why the author believed vampires to be descended from such a thing.

So… memory restoration would have to come first. And until then, Katsuki would have to keep Izuku fed and contained. He didn’t know what else to do. He wasn’t willing to accept defeat.

He wasn’t willing to stop moving, because then that grief he didn’t know how to face would catch up to him.

Chapter Text

Katsuki

Five months into their stay in the cave, Katsuki encountered a potentially catastrophic issue.

Most of the time these days, Izuku seemed almost human sometimes, especially in the evening when Katsuki had just given him more blood. If Katsuki ignored all his instincts screaming at him to run for his life, that is.

Sometimes, on the rarest occasion, Izuku would almost sound like himself. When he would inquire further, almost sounding like he was asking out of genuine curiosity, about a detail in a story Katsuki was telling him.

But when blood was involved, he was so quickly reduced to the predator with overwhelming bloodlust that he was.

When it came to Katsuki’s blood, Izuku was always ravenous for it. It was the only thing he looked at the moment Katsuki uncapped a waterskin, enough that eventually Katsuki got brave and would allow himself to stare at Izuku while he drank.

Izuku’s eyes were the same, but they were widened with a crazed mania as he stared at the bowl and the blood. His teeth looked sharper, his canines a bit longer than they did when he was human. Freckle still dotted his cheeks. Katsuki’s heart ached whenever he looked at them, so he usually avoided doing so.

Katsuki encountered the potentially catastrophic issue a day after he’d managed to kill a boar for the first time.

He’d been shaking from excitement and relief as he’d immediately collected and preserved its blood. He’d decided to give Izuku some the next day, using up the older blood he’d already preserved.

The timing was perfect, as Katsuki woke up sick. Dizzy. Nauseous. His head was pounding, his nose congested. The days had been growing colder recently. He must’ve stayed out too long and caught a cold. As awful as he felt, he didn’t feel that he was remotely able to stand draining his own blood. That already made him feel sick and weak, and he needed time to heal.

What he hadn’t been anticipating was Izuku’s reaction when he tried to give him the animal blood.

Rather than dive into his meal with a slightly frantic intensity, Izuku had watched Katsuki levitate the bowl over with a slight frown on his face. He’d stared down into it even once it was within reach, unmoving. Then his head snapped up, and Katsuki was glad his eyes had been averted slightly.

More and more often, Katsuki had been allowing Izuku’s hands to be restrained in front of his torso rather than behind, at least when he ate so he could use his hands to drink the bowl. By now, at least, he trusted that Izuku wouldn’t attempt to make the bowl into a murderous projectile by throwing it at him at the speed of sound or something.

Instead, Izuku used his freedom of movement to gesture with his shackled hands down at the bowl as he asked sharply, “What the hell is this?”

Izuku had gotten even more combative and sharp-tongued in many ways, and Katsuki occasionally wondered if he was to blame for that. If this memoryless Izuku was learning from him and how he acted. So often, Izuku’s manner of speech imitated his own—especially when they argued—so intensely that it sometimes made Katsuki’s head spin.

“It’s animal blood,” Katsuki responded tiredly, stoking the fire and sniffling. He was hunched in front of it, wrapped in far more blankets than usual. “I killed a boar yesterday.”

“Obviously I know it’s blood,” Izuku snarled with an excessive amount of aggression, in Katsuki’s opinion. “It’s not yours.”

Katsuki nearly groaned in frustration. Was Izuku really being picky about this? The vampire that was constantly complaining about how he wanted more blood had the nerve to turn his nose up at Katsuki actually trying to offer him more blood?

“Ain’t you always complaining about being thirsty?” Katsuki snapped. “You’re always asking for more blood, so shut up and accept it.”

“That’s—I meant—don’t you—” Izuku sputtered for a moment, then sounded almost offended as he replied, “More of your blood! I’m asking for more of yours!”

“I’ve told you why I can’t give you more of mine!”

“And I’ve told you that if you let me bite you, I can drink more without hurting you!”

Katsuki groaned in frustration, rubbing at his bleary eyes. He really couldn’t handle his own aggression being mirrored back at him like this. His Izuku—Deku—might’ve argued with him plenty, but over specific things—mainly if he thought Katsuki was being unfair or too mean or something. Unfair about reasonable things. This was definitely not a reasonable thing.

“I’m ill,” Katsuki said. “I feel weak and I can’t handle the blood loss right now, anyways. So stop being annoying and just drink it.”

“So? I don’t mind!”

“You don’t mind what?”

“I don’t mind if it tastes weird because you’re sick. And it won’t get me sick, obviously.”

Katsuki snorted in complete, unamused disbelief. “You’ve got to be kidding me.”

“Your blood often tastes funky anyways because you’re always so sad and miserable,” Izuku added, matter-of-factly. “I’m used to it.”

“God, you’re such an asshole,” Katsuki groaned, rubbing his palms over his eyes again. Of course, he meant that vampire-Izuku was such an asshole. So completely different than his Izuku.

He huffed out a long breath, trying to breathe past the ache of the memory of the human Izuku’s smile. Of that stupid Deku who was always way too concerned about Katsuki’s well being growing up. Always checking up on him, always freaking out way too much when Katsuki was sick or that one time he slipped and fell into that damn creek in the woods behind their houses.

Of that stupid, stupid Deku who cried for days when Katsuki had fallen ill as a child because he’d been convinced that Katsuki was going to die.

That Izuku looked at him with eyes way too wide and starry and worried about him way too damn much. This Izuku stared at him as if he wanted to eat him alive—because he did—and seemed to not care less whether or not he was sick except to the extent it affected him.

“Just give me your blood,” Izuku said, as if he was offering some sort of deal. “I don’t care.”

Katsuki sneered in his direction. “It’s not about your comfort. It’s because I can’t handle the blood loss! I already feel dizzy!”

Izuku was quiet for a moment. Then he said, “Then just give me a little. I’ll take less until you get better, okay? I can handle my thirst better now. I can take it.”

“Unbelievable.” Katsuki glared at the fire because he couldn’t glare at Izuku. “You’re a selfish bastard, you know that? I’m sick, and you’re still shamelessly asking me to risk my health!”

“I have to eat!” Izuku protested, only growing more combative and indignant. “You’re keeping me captive here, if you haven’t noticed!”

“And I gave you some damn blood! So shut up and drink it!”

“I’m not drinking this!”

“Stop being picky, for fuck’s sake!”

Katsuki could hear Izuku’s loud, furious huffing. He also wasn’t sure if he was just going insane after all this time, but he swore sometimes that he could sense Izuku’s presence and emotions with greater intensity. At the moment, he could feel the rage practically radiating off Izuku.

“I’d rather starve,” Izuku spat after half a minute had passed.

“Then starve! See if I care!”

Katsuki tried to ignore the alarm that flowed through him at the idea of it. As he watched Izuku curl his lip and stick his nose up at the blood he was offering him—despite how he knew he was thirsty—he realized he might’ve majorly fucked up.

Izuku would rather starve than drink animal blood? That really, really wasn’t good. That meant human blood was the only thing on the menu.

Katsuki had heard legends of vampires draining large animals of blood. Was that a different creature that had been confused with a vampire? Was it a specific kind of vampire? How the hell could he ever hope to take Izuku back into society if he still only wanted human blood?

Izuku let out a cry of rage. There were the familiar sounds of him yanking at the restraints and testing the magic barriers. As always, it was no good. After a few minutes, Izuku screamed again, even louder.

“Do you mind?” Katsuki snapped, so livid it was making his head spin faster. “I’ve got a splitting fucking headache over here!”

Izuku was huffing out his loud, furious breaths.

“You’d really let me starve?” he growled. “All that talk of not meaning me any harm and just trying to keep your stupid, shitty oath, and you’d let me starve?!”

“No, I tried to feed you, and you decided to be picky about it!”

“I can’t eat this! It smells rotten!”

“You’ve got to be kidding me.” Katsuki groaned, rubbing at his temples. “I killed the boar yesterday, Izuku. Stop being dramatic.”

Izuku said nothing, just continued huffing furiously.

Katsuki felt Izuku’s predatory gaze practically burning into him. Even with blankets pulled up over his neck like this, he felt as if Izuku’s gaze penetrated through them. He felt when Izuku’s eyes flitted from his face to his neck. He felt when Izuku was staring right at his eyes, probably desperately hoping that Katsuki would mess up after all this time and make eye contact.

“You’ve got to learn how to drink it anyways,” Katsuki said. “So just shut up and drink it.”

“Why the hell do I gotta do that? You told me yours was the only blood I was ever gonna get. Why’re you switching things up now?!”

“I said the only human blood, idiot! And I can’t always drain my own blood! Taking some of my blood every day already isn’t good for me. And what if I get injured, or sick again? I’m not gonna let you bite any humans, so just suck it up and drink it!”

Silence. Izuku had gone completely silent, outside the quieter, but still angry huffs of breath.

The quiet remained as the seconds ticked by, and like hell was Katsuki going to complain about it. His headache was throbbing in his temples.

But when he no longer felt Izuku’s gaze on him for minutes on end, he grew curious. His eyes wandered closer to Izuku. He’d gotten very good at looking at him without getting too close to his gaze. He saw how Izuku was kneeled, head ducked so his chin rested on his chest, entire torso heaving as if he’d physically exerted himself. Or like he was still overwhelmed with rage.

Yet, the damn bowl of boar blood remained untouched.

Katsuki had little sympathy, with how poorly he was feeling right now. He was pretty sure Izuku was being picky, seeing as there were so damn many accounts of vampires drinking animal blood. Vampires seemed to prefer human blood, but they’d attacked creatures of all kinds before. They attacked elves, dwarves, half-humans of all kinds. They attacked large animals such as bears and boars and elk most commonly in the stories.

One thing Katsuki was pretty certain about: their bloodlust overcame any preferences they had, in the end. Izuku would get over his weird pickiness when his thirst started to consume him. It wasn’t like Katsuki wanted to let him grow thirsty and out of his mind before he drank, but he didn’t have another choice.

Izuku still didn’t say anything as the minutes passed.

Katsuki ate his own dinner. He got ready for bed, sluggish with illness, glancing occasionally at an unsettlingly still Izuku. He mixed some herbs into a healing remedy, enhancing it with the limited healing magic he knew before choking it down.

All the while, his loneliness started to eat him alive. It was hard not to resent not having someone to help him. He’d never fully realized the privilege of always having fallen ill near someone who cared for him. His parents in his youth. Later… Izuku had taken care of him. He’d get fresh water and make food and fetch medicine for Katsuki so he could rest. He’d bring cool cloths for his forehead and check up on him.

And Katsuki would take care of him when he was sick. That’s what family did… and even in the beginning after their parents had died, when they hadn’t fully gotten along, they’d wordlessly taken care of each other. It’d been a given.

Now, Katsuki had to take care of himself despite how he felt the fever start to burn under his skin. Now, not once did Izuku ask how he was or how bad his illness was. Not once did Izuku think about anything except how to get more of Katsuki’s blood. Not once did he worry about how it would actually affect Katsuki or seem to try to understand.

Eventually Katsuki crossed over to his bedroll, intending to collapse into it. His eyes were watering from his illness, but the urge to cry was also growing.

He felt so very ill. And he missed Deku, his Izuku, far more than he usually let himself.

In that moment, Deku felt completely gone and dead, and Katsuki felt despair and grief start to break him down.

He was nearly to his bedroll when he heard it.

“Please.”

Katsuki froze in his tracks as Izuku’s hoarse, ragged voice cut through the air.

“Hah?” He was immediately fuming all over again as he suspected what Izuku was going to ask for. The tears still burned in his eyes, and somehow all his grief only fed the fire of his rage.

“Please.” Izuku was fully begging him, straining forward against the restraints. “Just a little. Just a drop.”

“You’re unbelievably cruel,” Katsuki hissed as he continued facing away. Tears trailed down his face, and he refused to wipe them away, because then Izuku would know he was crying. “Do you really not care at all about anything besides yourself?”

“I’m thirsty! I—I’m only asking because I have no other choice!”

At least Izuku had the decency to sound a bit bad about it this time. Even still, Katsuki’s rage was not quelled, because Izuku was still asking.

In that moment, Katsuki’s grief was redirected towards this version of Izuku. Suddenly, it felt as if the thing on the other side of this cave had been the thing that’d killed his oldest friend, and Katsuki began to tremble with the force of everything overwhelming him. His skin burned with fever. Sweat dripped down the side of his face as tears trailed down his flushed cheeks.

Still, he wanted to go to bed more than anything else. He searched within him for some scrap of patience in a move he never would’ve been able to accomplish in his younger years.

“You have a damn choice,” he all but growled out, still facing away from Izuku. The feeling of Izuku’s creepy-ass eyes on the back of his neck only made him want to lose it more. “I tried to give you another option. And I gave you my blood yesterday. If you stop fucking whining and bothering me, I’ll be able to get over this illness faster and give you more.”

“You don’t understand!” Izuku pleaded, voice going shrill with desperation. There was a loud slam as he yanked at the shackles yet again.

“No, I don’t.” Katsuki’s voice was cold and unsympathetic. He was tired and in pain and this selfish asshole in possession of his best friend’s body was getting on his very last nerve. “Drink what I gave you or shut the hell up, goddamn bloodsucker.”

He ignored how Izuku eeked out a squeaky noise of protest and lay down on his bed. He closed his eyes, ignoring when Izuku made several more attempts to call out to him. He dug his teeth into the inside of his cheeks to try and keep back the breakdown that wanted to tear through his body.

But he was careful not to break skin.

Katsuki was awoken a while later by a sound.

Sniffling. Sobs.

His eyes flew open, confused and alarmed. His illness made his head swim when he sat up. He recognized the sound of those cries. He hadn’t heard them in many months now, but he used to hear them so very often.

“Izuku?” he called. Fever delirium confused him for a moment, making him call out gently for his Izuku. “Is that you?”

His eyes were blurry from sleep and illness, and he hurried to conjure fire in his palm. Even as he recognized where he was, delirium made him delusionally hopeful. His fever dreams of his childhood still lingered in his mind. He heard Izuku’s cries and heard only Deku. When he was met with only more stifled sobs, he threw the fire in the firepit, looking towards the back of the cave.

Izuku was hunched forward on his knees but bent all the way forward so that his forehead touched the ground. He was trembling badly.

“What the hell?” Katsuki muttered under his breath, getting closer. “Izuku?”

Izuku shuddered out a breath. He whispered, “Please…”

Katsuki froze, and his worry immediately dissipated. He spotted the untouched bowl of animal blood.

Right.

Izuku was still being picky.

Katsuki’s shoulders slumped, abruptly swapping concern for irritation. “You’ve got to be—”

“Please, I’m begging you…” Izuku’s voice was strained with apparent agony.

Katsuki opened his mouth to snap at him, ignoring how his traitorous heart tugged at the sound of Izuku’s vulnerable, upset voice. Before he could reply, Izuku spoke again.

“Please imprison me elsewhere.”

Katsuki blinked slowly down at him. His feverish mind had no idea what the hell that meant. “What?”

Izuku took several shuddering breaths, pressing his forehead harder into the ground. His body was wracked with tremors.

“You’ve shown me mercy before.” Izuku sounded as if he was reasoning with himself. “Sometimes, you even seem to care for me for some reason, despite what I am. It’s very odd and I can’t figure out why, but… I can sense it. You care about me.”

Katsuki took a step back. He was thoroughly confused, and it was making him unsettled. Was he dreaming right now? Was this a fever nightmare? What was going on? Why was Izuku acting so strangely?

“I beg of you,” Izuku almost forced the words out, “imprison me elsewhere. Anywhere else. If… if you’re going to starve me, then… then…”

All Katsuki’s anger had left him for bewilderment and slightly delirious confusion. Mild annoyance still stirred around in his gut as his eyes darted over to look at the bowl of untouched animal blood.

He’d thought Izuku was being dramatic but… but was he wrong?

What the hell was happening right now?

Izuku trembled. Katsuki’s eyes widened as movement caught his eye. With his head on the ground, Izuku’s back and the arms tied behind them were in Katsuki’s line of vision. And Izuku’s arms were crossed as much as he could manage, and his fingers were digging into his own forearms. He’d pierced his own iron skin, and dark, inhuman blood was covering his hands, arms, and the back of his shirt. He hadn’t even noticed until Izuku shifted his fingers to dig in deeper.

“What the hell are you doing?” The words burst from Katsuki’s mouth in horror, taking a half step forward before he remembered the danger and jolted to a halt. His hands dangled in front of himself uselessly. “You’re hurting yourself, idiot!”

Izuku replied as if he hadn’t said anything, muttering hoarsely, “I don’t care where. Bury me underground. Seal me in a different cave. Just… please…”

He let out a sob that sounded way, way too much like Deku. It pulled aggressively at Katsuki’s heartstrings.

“I don’t understand what you’re talking about! Stop doing that!”

“Don’t keep me in the same room as you,” Izuku begged as his shaking fingers dug deeper into his own skin. His whole body shook as he sobbed again. “If you’re going to starve me, I beg of you to not be near me. Please. Have mercy, human. Please.”

Katsuki gaped at him, nauseous at the sight of Izuku’s blood and the sound of his crying. His fever was still making things hazy and he was so, so confused.

“Are you… are you being serious?”

“Please.” Izuku was crying harder, and Katsuki hated it. “You don’t understand… it’s agony.”

“What is?!”

Izuku snarled abruptly, and his head snapped up. Katsuki was quick to look away, his heartrate jumping out of fear. That’d been way too close. His heart dropped as the expected, primal fear tore through him. Izuku’s eyes on him activated that familiar fight-or-flight feeling.

“I can hear your blood in your veins and your heart beating,” Izuku hissed, and he no longer sounded like Deku. “I can smell you so much that I can almost taste you. And yet you won’t feed me. So have mercy on me and get away from me!”

Katsuki’s eyes widened as he all but stumbled back another couple of steps. He was almost too shocked, too thrown off by the sudden change from Deku to Izuku. His anger didn’t come back as quickly as it might’ve normally. “But… it’s only been a day. It’s been a little more than that.”

The laugh that Izuku let out sounded not at all like himself. It was a bit crazed, a bit a amused, a bit angry.

“Do you know nothing of what I am?! You seem to not understand, so did you really capture me without knowing anything?!”

“I know enough!” Katsuki snapped defensively, as his annoyance finally started to come back. “I’ve read that you can go many days without drinking blood!”

“Clearly you don’t!” Izuku snarled so meanly that it raised the hair on Katsuki’s arms and so loudly that it echoed off the cave walls. “That’s if I’d bled a human dry, you fool! If I bled multiple dry, then yes, I could go for a while! But you’ve never let me do that! You only give me a bit of yours every day! You starve me every single day!” He was shouting now, spitting mad. “I’m always thirsty! Always! I’m always in agony! So no, I can’t go for days without blood!”

“I tried giving you blood!” Katsuki was so shocked he could only give his previous defense.

Izuku laughed another maniacal laugh. “It’s as if you’ve tossed diseased meat to a starving man, you stupid human! If I drink that, it’ll make me sick! It’ll make it worse!”

Katsuki gaped in his general direction, horrified.

He wasn’t sure why he believed him. For all he knew, Izuku could still be lying. He could be pretending. He could be being very, very dramatic. He’d read that vampires could drink other blood, so much so that until now, he’d been convinced Izuku was just being incredibly picky.

But Katsuki believed him. Maybe it was how he shook, or the pallor of his skin that was discolored from its usual sickly paleness. Maybe it was how his voice wrenched from his throat or how his fingers had dug disturbingly far into his own flesh.

“There’s nowhere for either of us to go,” Katsuki said hoarsely, as guilt stirred up, sudden and intense, somewhere within him. “There’s nowhere secure enough for you or me. I’ve scouted some of the other caves, but there aren’t many nearby.”

Izuku sobbed, slumping back down. His face hit the ground had enough to crack the stone and Katsuki startled, wide-eyed. Izuku’s whole body was wracked with sobs.

“I—I can’t go anywhere.” Katsuki found himself floundering for more explanations, something to make the situation minimally better. “I’m very unwell. I’ll get sicker if I go out in the cold.”

Izuku just sobbed into the rock beneath him. He sounded so pained that Katsuki’s heart started to ache.

Katsuki crossed back to his side of the cave, all but falling onto his bedroll. He stared in horror up at the ceiling. His head felt light from walking around and the sudden flurry of emotions. His ears echoed Izuku’s sobs.

It was only another minute or two before he grimaced, reaching a decision. He sat up, reached for his knife and the nearest bowl, and sliced open his palm.

Immediately, Izuku’s sobs cut off, leaving deafening, abrupt silence. Katsuki knew without looking that Izuku had moved. His head had snapped up, and Katsuki felt his eyes on him like a nearly physical thing.

“I can’t give you much,” Katsuki gritted out as he let the blood drip into the bowl.

“That’s fine,” Izuku replied immediately. His voice was quick and curt. He was desperate.

Katsuki frowned down at the small pool of blood forming. His head swam dangerously. He turned the palm up and sealed the wound. He normally would never, ever open a wound anywhere near Izuku, but he couldn’t go outside right now. He used a levitation spell to move the bowl over to Izuku. By now, he hardly had to concentrate or look to get it in the right place.

As soon as it was close enough, Izuku let out a strangled noise and then dove down to drink it up. The sounds of his desperate drinking and groans from low in his throat made Katsuki’s hot skin tingle weirdly.

He rolled over and stared at the cave wall, wondering what the hell he’d done.

It was a week later when Katsuki broached the subject.

“You never told me you weren’t getting enough blood,” he said lowly as he sharpened his knives by the fire.

Izuku didn’t reply for a long moment. Finally, he said, “I tell you I want more all the time.”

“Yes but I figured you just want to kill me. Or that… I don’t know.”

Izuku said nothing.

Katsuki gritted his teeth, frustrated, as he continued sharpening the knife in his hand. The loud scraping of it echoed around the cave. “How much do you need? To feel that you’ve had enough. Or where you don’t feel like you’re still starving, at least.”

“I’m not sure exactly,” Izuku murmured. “I’m not sure I’ve ever had it. I can’t remember ever having, anyways.”

It was quiet for a few minutes except for the scraping of the knife against stone.

“Well, I can’t let you kill me or anyone else,” Katsuki grumbled. “I guess you’ll have to learn to drink animal blood.”

Izuku made a quiet noise of frustration. “I told you, I can’t.”

“I’ve read that your kind drinks animal blood and other non-human blood,” Katsuki argued.

“Well, I’m telling you I can’t!”

“Damn you.”

Izuku said nothing, but somehow Katsuki could sense his discontent without even looking. He could feel Izuku’s exasperation, his anger. Underneath that…  Katsuki sensed something that felt oddly like fear.

He must be imagining it. Or feeling his own fear.

“What do you suggest I do then, hah?” Katsuki asked. “I’m trying my best to work with you, but—”

“Let me bite you.”

“Shut it, I’ve told you I’m not letting your bloodthirsty ass anywhere near me!”

Rather than snap back, Izuku’s reply was oddly quiet and resigned. “This… this is fine, then.”

Katsuki’s hand holding the knife stilled. “What’s fine?”

“This. You giving me what you can.”

Katsuki stared blankly at the fire. He didn’t understand. “You’d rather drink less than drink animal blood?”

“Yes.”

Katsuki scowled, his head tilting in Izuku’s direction. As always, he didn’t look all the way towards him. He was so confused, uncertain if this was some kind of trick.

In the end, he just resumed scraping his knife against the sharpening stone, frowning pensively. He would need to go into town tomorrow and continue his research on vampires.

Chapter Text

Izuku

The human was a strange creature.

Izuku knew this much for certain. Despite how he couldn’t actually remember any other beings, he still found the human to be very strange.

He also found himself… very obsessed with the human.

It was natural, really. Izuku spent many hours staring at the human from afar, only receiving his meals in rationed amounts. It made sense that he craved the human with every fiber of his being. That his teeth wanted nothing more in life than to sink into his neck and not let go.

But in the month since the human had tried to give him animal blood, something had changed in Izuku. Since those few days when he’d been given even less blood than usual, his obsession had worsened significantly.

Those few days had been miserable. Yes, a lot better than if he’d had nothing at all but still a complete hell. Izuku never again wanted to go without the human’s blood. Ever. He would do anything. He grew more certain of this by the day, by the hour, by the minute, by the second.

With each tick of the human’s heart, Izuku grew more certain.

He knew he wouldn’t kill the human now. No, no… even if he got free he would keep the human alive. He would keep him alive and feed off of him as much as he wanted. Until he was truly satisfied.

Izuku was certain that he could take much more from the human than what the human willingly gave him without doing any damage. He knew that the venom in his teeth would help the human replenish his blood faster and help ease his symptoms until he did so. He didn’t know how he knew these things, but he was very certain they were true.

The human didn’t care. It was clear by now, six months into this captivity, that the human intended to keep him like this forever. And Izuku’s desperation had begun to affect his treatment of said human.

The thirst of those few days when the human had been sick haunted him. That had been actual hell. It felt like his entire body was on fire, so much so that he’d resorted to digging into his own flesh to keep from screaming bloody murder. As infuriated as he’d been at the human, at the time there was still a part of him that felt it too cruel to disturb the human’s rest in such a way. Especially because pissing off the human felt like it could only end in starvation for himself.

Now? Izuku harbored a fear deep within his being that the human would get angry enough with him and leave him. It made him less combative in general, less willing to anger the human at all. He knew his new rather submissive behavior was weirding the human out. He could sense how the human was deeply unsettled and even concerned by how cooperative he was being.

Izuku didn’t care. He’d get on the human’s good side and stay on it.

Because there was one last thing he’d realized those days when the human was sick.

He didn’t want to drink any other blood. The animal blood had been so unappetizing that he’d nearly vomited at the idea of drinking it. He wasn’t sure that it would even do anything for him if he managed to swallow it without gagging.

For better or for worse, this human was his food source.

Izuku wasn’t dumb enough to risk that. Not anymore. Not now that he understood the situation more fully.

But as the days ticked by, Izuku wondered frequently about the reason behind it all. The human kept him like a particularly difficult pet—imprisoned him, never approached him, fed him from a bowl, talked to him gently when he had the patience and yelled at him when he had none. He kept his hands bound almost at all times; supposedly, he was convinced that Izuku could use them to counter his magic.

It was such an odd thing that they had going on here, and Izuku honestly had no idea what the human got out of it. He wondered what the hell the oath was that the human swore, and to who. Were humans so honorable that they would isolate themselves and keep themselves in misery to uphold their vows? Because it was true that Izuku could taste the deep sadness in the human’s blood. It was sometimes far more intense than others, but it never left.

He was unhappy. Deeply. So much more than he showed on his stoic face. After all this time, by observing the human and noting the taste of his blood, Izuku had realized that when the human got sadder, he got quieter. He talked to Izuku less. His face grew more stoic. He moved around more. He spent longer outside the cave.

Who was this human? Why did the human seem to speak to him almost kindly sometimes? Why did the human seem to put so much effort into his comfort despite how Izuku never asked for it and couldn’t care less about such things?

Were all humans as strange as this? The human never left or killed him or hurt him despite how Izuku had threatened him many times throughout their time in this cave. He got angry with him sometimes, but the most he did was go quiet or leave for a few hours. He never punished him for saying such things—with magic or by withholding blood or anything.

Izuku knew the human was a warlock. His skill with magic was extensive. Precise. Powerful. And yet, the human only restrained him. Knocked him out painlessly when he needed to approach him but woke him up right after.

Were all humans this… kind?

And why was the human always so sad? Based off his stories, he’d largely lived a happy life. A life of great adventures with his childhood friends, travels with his closest friend, and studies of magic.

Izuku didn’t understand the human, but at least that kept things interesting.

He often wondered what the hell it was that he was supposed to remember, that apparently would buy him his freedom.

If you remember me, then you’ll figure it out.

What could he recall that would explain all this?

One evening after Izuku and the human had both had their dinner, the human spoke solemnly from where he was stitching up a shirt by the fire.

“We can’t stay here.”

Izuku felt something drop in his chest as cold fear consumed him. “What?”

“It’ll be winter soon. It’ll be too dangerous. I’ve already gotten sick once, which obviously wasn’t great for either of us.”

Izuku tried not to panic. It wasn’t like he liked being in this damn cave but…

“What does that mean for me?” he asked, trying to keep his voice as devoid of emotion as possible. “You intend to keep me captive elsewhere?”

The human didn’t reply right away, continuing his stitching. Izuku watched him. His favorite thing about the human would always be his blood, and thus his favorite thing to stare at was his neck, over time Izuku had found that he enjoyed staring at any part of the human.

The human had nice hands. They were strong and calloused. Capable. Even now, they patched up the fabric with careful, precise movements that Izuku was oddly entranced by.

“I need to figure a few things out,” the human said finally. “And then yes, we’ll be moving on.”

Izuku’s gaze trailed up to his blood red eyes. After all this time, he was very attuned to the human. To his blood and heart and breath, yes. But also his expressions, his emotions, how he felt…

The human was worried. Anxious. The set of his broad shoulders was tense, and his brows were furrowed in thought.

“Figure what out?” Izuku asked tentatively.

“What to do about you.”

Izuku’s eyes widened in alarm. The words burst from his mouth before he gave them a second thought, “Please don’t leave me behind.”

The human jolted in surprise, gaze tracing across the cave towards him. Izuku instinctively looked away. At this point, it was one of those things he did to try and be non-confrontational with the human.

“What’re you talking about?” The human sounded annoyed.

Izuku clenched his eternally aching teeth. Then he unclenched them and said, “You told me at the beginning that I would rot in this corner before breaking free from it. So—”

“I’m not leaving you to rot, Izuku. For fuck’s sake!”

“You told me you won’t let me hurt anyone, so I’m just telling you that even if we go out there, I won’t!” Izuku replied a bit desperately. “You don’t have to leave me or kill me, I’ll—”

“I wasn’t gonna do either of those things! Shut it!”

Izuku’s mouth snapped shut, but he felt no less uneasy than he did before. When he felt the human’s gaze leave him and saw him return to his work in his peripheral, Izuku looked back over at him.

A few minutes passed before the human said, quiet and serious, “I’m never gonna leave you, Izuku. I just need to figure a few things out.”

Izuku tried to find comfort in this, but the fear wouldn’t dissipate completely.

Izuku had started to wonder if he’d been abandoned. Or if something had happened to the human.

The human had left before dawn and was gone for so long that the sun crossed the sky. The moon had fully risen by the time he finally returned.

Relief surged through Izuku. He’d been trying to free himself all day and, as always, the human’s magic had not budged. He’d been half convinced he was going to die here, left to starve. The human was never gone for nearly that long.

“I’m back,” the human grumbled as he threw down his pack and the other bags he was carrying.

Izuku was far too thirsty to be curious about any of them. His vision had locked in on the human’s neck. As always, it taunted him. A desirable but completely unreachable thing.

“I know you’re thirsty,” the human grumbled.

Izuku’s teeth ached, and he clenched his jaw and unclenched it as he often did. That was another part of this hell the human kept him in—he could never bite anything. Ever. He drank the blood from a bowl—blood that was often cold—and his teeth always, always ached. They demanded relief, and the human didn’t seem inclined to ever offer it to him.

The human levitated Izuku’s bowl towards himself, then removed the cap from the waterskin.

Izuku didn’t notice right away. Well, he sort of did notice, actually, but he was so focused at staring at the human’s neck and imagining in great detail what it would be like to sink his aching teeth into his flesh that he didn’t fully register that there was something off about the blood being poured into the bowl.

Izuku was so enamored by the ticking pulse under the human’s skin that when the bowl hovered down in front of him, he also didn’t really notice it—which should’ve been his second warning.

But when Izuku ducked down to drink more out of instinct than anything else, it was immediately apparent when he had very nearly started to drink. He jerked his head back, flinching, smacking his lips in displeasure as the smell and taste of the blood permeated his senses from so close.

Confused, he glanced over to the human, only to find that he was watching him carefully with his intense, captivating red eyes. The human’s eyes immediately darted off to the side slightly when he looked up.

“What is this?” Izuku asked, confused.

“Blood, obviously.” The human’s voice was tense.

Izuku sensed his strange demeanor from here. He was anxious and uneasy.

Izuku glanced down at the bowl again, then back up. He narrowed his eyes, eyes tracing all over the human. He inhaled deeply, using all his senses to try and figure out what was different. As always, a degree of misery and stress clung to the human like a second skin, but otherwise he smelled healthy.

“Are you ill again?” Izuku asked, skeptically.

“Hah? No.”

“This isn’t yours.” Izuku nodded his head in the direction of the bowl, frowning unhappily.

“So?”

“So, why not?”

“It’s human blood, isn’t that what you like? Picky bastard.”

Izuku glanced down at it again and back up. He felt a growing unease within himself now. He shuffled in place, trying to stave off the feeling of dread within him.

“Why isn’t it yours?” he asked, trying to keep his voice from shaking.

He wasn’t sure why he was suddenly so terrified. But… but… did this mean the human would be leaving him? Imprisoning him elsewhere? Would the human be unable to give his own blood when they left this cave?

Izuku nearly shivered in horror at the thought.

“I thought you were thirsty!” The human barked. “You’re really not gonna drink it?!”

Izuku glanced down at the bowl again unhappily. It didn’t smell rotten in the way that the animal blood had. It smelled unappetizing, but he knew it would technically appease his thirst. It would likely taste bland at best and rather disgusting at worst. He wasn’t overly tempted to find out.

And yes, he was very thirsty. But how the hell was he meant to drink this while the human stood on the other side of the cave, perfectly capable of giving him blood? Was this a new form of cruelty? What did the human want from him?

“Do I… have to?” Izuku asked weakly, looking over at him with a wince.

The human gaped at him. Again, he said, “I thought you were thirsty!”

“I am,” Izuku replied, his gaze locking on the human’s neck. He watched as the human reached up and rubbed at his neck, right over the vein.

Izuku’s own hand twitched with an odd desire to grab at the human’s hand with his own. He could hold it captive while his teeth became acquainted with the human’s neck.

“So drink it,” the human snapped, turning away towards the bags.

Izuku felt tears burn his eyes unexpectedly. What was this? What game was the human playing? Why did he suddenly withhold his blood? Was this a test somehow? What was the right answer?

The human had said they couldn’t stay here. That they had to leave. Was the human planning on leaving him in someone else’s care? Was there a reason he’d no longer be able to give Izuku his own blood?

Izuku’s mind raced. As much as he’d spent many, many hours despising the human for keeping him captive, he also very, very much so would never feel at peace being separated from him. If he couldn’t bite the human, being able to taste him and see him and smell him was enough. He hadn’t always thought so before, but suddenly he was very, very certain it was enough.

It was much better than the alternative.

“Why isn’t it yours?” Izuku asked again after he’d spent several minutes watching the human sort through things.

The human stilled, then turned to look at him with widened eyes. Izuku could hear how his heart was racing madly, and that only confused him more.

“Does that matter?” the human asked, in a voice that was far too even and void of emotion.

Izuku’s gut stirred uneasily as he tried to figure out this damn game. Did the human… want him to ask for it? Was that it? Despite how the human had kept him captive this entire time, he’d never actually thought the human to be purposefully sadistic. When Izuku had revealed that he’d been starving, the human had seemed genuinely horrified by it.

So… what was this? What was this, if not the human mocking him for his addiction? Did the human not realize what he’d done? Did he not feel the bond that had begun to form between them? How could he not sense it, when it consumed Izuku so wholly from his end?

“Y-yes,” Izuku stammered out. He realized that the dread had opened up a hollow pit in his stomach.

“It matters… that it’s not mine?”

Izuku frowned deeply. Did the human really not know? Did he really not sense it at all?

“Yes,” he repeated. Growing desperate, he added, “I don’t… I don’t understand. Do you want me to beg for it?”

“Hah?” The human’s face twisted into a look somewhere between confusion and disgust. “Beg for what?”

“Your blood. Do you want me to beg for it? Is that it?” Izuku swallowed, shifting on his knees.

Had he really fallen so far? As he listened to the racing heartbeat of the human… he was certain that he had. He was desperate. He would do anything.

“I will,” Izuku added on quickly. Immediately, he started to plead, “I’m… I’m so thirsty. Please, I—”

“Stop, stop, stop,” the human immediately snapped, waving a dismissive hand his way.

Izuku’s jaw snapped shut. His eyes were blown wide with uncertainty and terror. He watched, trembling, mind racing, as the human put down what he was holding and walked over. His eyes widened further, confusion and terror spiking as the human approached him.

Of course, the human approached him to redo the magic binding him here. Izuku knew that because even though the human knocked him out, Izuku could smell that he’d been there afterwards. But he never got all that close otherwise. He usually kept to his end of the cave.

But now, the human got closer, and the ache in Izuku’s teeth grew rapidly more painful. It spiked up into his skull. He couldn’t get himself to look away from the human completely, but he kept his eyes locked on the human’s neck rather than attempting to make eye contact.

Izuku stared as the human stopped, standing a few feet before him. Izuku panted, open-mouthed, drool gathering in his mouth just like his very first day in this cave. He wasn’t out of control now as he was then, but he felt just as empty of higher thought. His senses were overwhelmed by the sound of the human’s heartbeat and rushing blood. His smell filled his nose, his teeth screamed to sink into flesh, and his fingers twitched with an urge to touch.  His eyes watched the blood moving under the skin of his neck, and he was certain he’d be content to stare at it for all eternity.

He was at this human’s mercy.

If that had been the human’s goal… he’d done it. In that moment, Izuku was certain he’d do anything if it got him more of that blood. If he didn’t have to be separated from the human.

“And if I told you that you had to drink it?” the human asked, in a hardened tone.

“H-had to?”

“Is this like with the animal blood? It’ll make you sick?”

For a long moment, Izuku couldn’t even comprehend what the human was talking about. Then he distantly remembered the bowl of human blood in front of him. He numbly shook his head. His voice came out breathy, “N-no. I’ll… I’ll drink it if you want me to.”

The human scowled and Izuku nearly winced.

Was that the wrong answer?

“If I… if I drink it, can I please have some of yours?” Izuku was begging again before he’d given it a second thought. “Please. I’ll… I’ll drink it all either way, but can I… can I please have some of yours?” He started to pant, swallowing the saliva that kept gathering in his mouth, as he listened to the human’s heart start to beat faster. “Just… just a drop of it. Please.”

The human stared at him for a long moment, then just summoned the bowl to his hand and turned to walk away.

Izuku immediately slumped back against the cave wall. Now that the human had gotten so close, the distance felt so intolerable. His senses stretched, following the human, but they screamed at him in protest as they did so.

No, no, no, no, no! It was like his entire body was protesting that the human was getting further away. And nothing was more upset than Izuku’s aching teeth.

But aside from his raging senses, Izuku felt no less terrified. No less confused. He watched the human walk back over. He watched the human grab another bowl and another waterskin.

Izuku’s spirits rose… and then immediately fell when the blood hit the bowl. He could smell from here. It was a different human from before, but not his human’s.

“Is this a test?” Izuku asked breathily as the human finished pouring the drink. He watched as the human capped the waterskin and stood, walking back over.

The human floated the bowl over back in front of Izuku. Izuku didn’t look at it, instead staring up at the human’s neck as he waited for an answer.

“Yes,” the human replied simply.

Izuku felt the fear jolting in his chest. “In what way?”

“It wouldn’t be a test if I told you the answer, would it?”

Izuku felt tears well in his eyes. His overwhelmed senses made the emotion rise and take control of him with ease. He whispered, “But what if I fail? What will happen to me?”

The human frowned deeply. “Nothing’s gonna happen to you, Izuku. I’m just trying to see something.”

“Are you going to leave me?” Izuku felt the tears overflow and trail down his cheeks.

“What? No. What’re you talking about? I told you I wasn’t gonna do that!”

Izuku wished he felt relief. He wished he believed the human, but nothing was making sense. Izuku’s body screamed at him in horror, and at the moment he felt incapable of even handling the human walking across the cave from him, much less the human leaving him completely.

“I’m sorry about when you were sick.” The words burst hurriedly from Izuku’s mouth. “I’m so sorry. I—I don’t need more than you’re willing to give me. I’m not even that thirsty!”

It was a lie, of course. He didn’t care. Whatever it took.

“I can easily live off what you’ve been giving me!” He insisted. “Please, please, you won’t hear me complain again. Not, not even if you get sick. I’m sorry for how I acted! I—I can go a day or two without it!”

Again, it was a lie. The thirst had been an agony that pushed Izuku’s limits to the extreme. He’d felt like he was going to go mad with it. Still, if that was the price he’d have to pay… he’d pay it.

“Izuku, calm down, okay?”

The human’s voice was shockingly gentle, and it made something deep within Izuku stir. That sometimes happened with the human. Some deep-rooted part of himself responded in kind. Some part of Izuku that tugged at memories that’d long left him. As if his mind was trying to recall them, but when it did, it came up blank.

Déjà vu.

“It’s okay,” the human reassured. “Everything’s okay.”

“I don’t know how to pass your test,” Izuku cried, squeezing his eyes shut as his senses screamed, his teeth ached, and his mind searched for something that just wasn’t there. “Just tell me what to do and I’ll do it.”

His eyes flew open, and his gaze found the blood in the bowl as something clicked mentally. If the human was tired of giving him his blood… maybe he wanted Izuku to drink other blood sometimes. Would he be given the human’s blood less frequently? Was that his punishment for how he’d acted the other night? Had the human reached the limits of his kindness?

“You… you want me to drink that, right?” Izuku gulped, staring at the unappetizing blood.

Somehow, with his human standing so close, the blood in the bowl seemed even more unappealing. Like it would taste little better than if he licked the charcoal in the firepit or the bottom of the human’s shoes.

“No.” The human’s voice was abruptly hardened. Commanding. “I don’t.”

Izuku’s eyes burned with confused tears as his head jerked back up to look towards the human.

Before he could question it, the human added, “I’m going to leave that there tonight. If you haven’t had any by the morning, I’ll give you even more than your usual amount of my blood, got it?”

Izuku’s eyes widened. He was jerking his head in a nod right away. “O-okay, I won’t, but… but do you… do you have to wait until morning?” He winced. “I won’t drink it. I’m just… can’t I have some of yours now, please? Just a bit?”

“No. That’s part of the test.”

Izuku frowned unhappily as the human turned and walked away. He glanced down at the bowl as he again slumped back against the cave wall.

He was very thirsty. He was. It hurt a lot. Especially now that his human was back and he could hear his blood and smell him. His senses were crying. Protesting. Taking over a good portion of the space in his mind.

So the human didn’t want him to drink this blood. Was that really the test? Was there a test within the test?

At least… at least his human said nothing would happen. That he wouldn’t leave. Izuku hoped that was true.

Izuku stared at the human, eyes locking on his throat and again moving his teeth to clench and unclench against each other. It wasn’t like the human’s blood lingered in his mouth after this long anyways, so after a second he sunk his canines—which always ached the worst—into the inside of his lips.

Even as the hours passed and his agony grew, the bowl of blood never drew his gaze away from his human. His lips and tongue healed every time he sunk his teeth into them, and the stinging pain helped him feel like he wasn’t going to completely lose his mind. He was never really tempted by the blood so much as tormented by the distance between him and his human. He sought reprieve, which he might’ve tried to seek from the blood in the bowl, but the human had told him not to, so he put it from his mind.

It was like the promise of a singular gold coin now or the wealth of a king in the morning.

There was never any contest between the two.

Chapter Text

Katsuki

Of course, it’d been Katsuki’s goal from the very beginning to try and get Izuku to have a craving for his blood specifically. The moment the light had left Deku’s eyes, Katsuki had sliced open his own palm to try and create that bond he’d heard vaguely about. He’d been hoping that he could help Izuku gain some sort of control, and potentially also keep himself from getting killed if he’d been unable to contain Izuku in the beginning.

But admittedly, Katsuki wondered now if it’d worked a little too well. It seemed that the outdated material he’d heard about this stuff from didn’t know the half of it.

Katsuki had posed as a doctor in a nearby town—one town further than he usually went to and in disguise—and asked for people to donate blood samples for his research. Not the most ethical move, but certainly a good deal more ethical than any other method of gathering human blood to offer up to a vampire. He wasn’t sure how else to test Izuku’s reaction to other humans, and this felt way safer than just bringing a vampire out in public around a bunch of unsuspecting humans.

So far, Izuku seemed entirely indifferent to the human blood. Unlike the animal blood, he seemed willing to drink it, but only if told to do so. He seemed mostly worried that Katsuki was going to stop giving him his own blood. If given the option between Katsuki’s and anyone else’s, Izuku would apparently always choose Katsuki’s.

It was both great news and potentially horrible news.

The good news? Izuku seemed entirely uninterested in any blood that wasn’t Katsuki’s. That was perfect in terms of the safety of the general public. If he brought Izuku out of this cave, then it was entirely possible that Izuku would still seem more interested at staring at Katsuki’s damn neck than anything else.

The less great news was that if Izuku didn’t want to drink from anyone else but wasn’t satisfied by what Katsuki could give, then where did that leave them? Had Katsuki unintentionally doomed his best friend to a life of eternally feeling thirsty to some degree?

It was also less great news for Katsuki himself. In fact, it was incredibly daunting to realize that all of Izuku’s bloodlust was entirely for his blood. That the bloodlust frenzy wasn’t for any blood, but just Katsuki’s.

Had it been like this since the beginning because Katsuki had fed him his blood during the transformation, or had he gotten Izuku too accustomed to his blood in the months in this cave? He had no way of knowing, but with how Izuku had cried and begged for Katsuki’s blood, there was likely no going back now.

Surely that meant Izuku wouldn’t want to kill him, right? That he would go to great lengths not to kill him, if he somehow saw Katsuki as his only food source?

Katsuki definitely hadn’t considered this option when he’d given Izuku his blood during the transformation. And of course… he hadn’t known then that vampires didn’t remember their human lives. He hadn’t comprehended that Izuku could be so entirely different. He hadn’t had time to think though all the what-ifs after Izuku had been bitten by that vampire.

One thing was certain. Having this version of Izuku essentially addicted to his blood and his blood only was far more unnerving than Katsuki wanted to admit to himself. This version of Izuku that still activated his fight or flight every time he looked at him.

This Izuku who stared at his neck more often than not. This Izuku who seemed to have very little desire for anything outside sinking his teeth into Katsuki’s neck. This Izuku who seemed far more animalistic than human sometimes, or at least, far more instinct-driven than humans typically were.

Katsuki would just have to do what he’d done all this time and keep trying to figure things out as he went along. Again, this had sort of been his goal from the beginning. He’d wanted to make it so Izuku would only drink from a willing source. He’d wanted to try and give Izuku a second chance at life, where he’d be able to functionally be human in most ways.

If he was careful, maybe this was his way to get them back to that life.

Katsuki had been working on packing up their things and consolidating their belongings. He could feel a chill in the air and knew winter would blow in within the next week or two. They would need to move down the mountain before then, at least.

The idea of releasing Izuku from the makeshift prison he’d kept him in for all this time had Katsuki feeling more than a little anxious. Originally, he’d not intended to let Izuku out until he’d regained his memory, but he also hadn’t thought it would take this long. Winter had returned long before Izuku’s memories, and Katsuki was left with a difficult new situation.

Could he control Izuku? Could he keep his promise to the human Izuku and keep him from harming anyone? Was it really safe to bring a full-fledged vampire to where humans were knowing that Izuku wasn’t exactly averse to the idea of biting or killing?

Katsuki didn’t know for sure. He didn’t know and there were too many factors.

But at least, he knew Izuku had some sort of weird dependency on his blood to some degree. And he would have to work with that. The downsides of this situation brought things he’d have to figure out, but at the very least, he could take advantage of the upsides.

A few days after he’d tried giving Izuku the blood of other humans, Katsuki had finished packing up most of their things. If things went well, they’d leave in the morning. If they waited much longer, it could snow, which would make things far more dangerous.

He decided to try and make things clear for Izuku. It wasn’t exactly the nicest thing he’d ever done, but Izuku’s apparent obsession with his specific blood made for good leverage. Applying that leverage would help Katsuki feel more secure about all this.

“You understand that it’s dangerous for me to bring you out of this cave, right?” Katsuki asked as he stirred his last stew in this damn cave.

He knew without looking that Izuku was listening. Izuku was always listening. Always watching.

“Yes,” replied Izuku quietly.

His tone was strange enough that Katsuki looked over towards him curiously. Almost immediately, Izuku’s gaze trailed off to the side, towards the wall. Katsuki looked at him carefully.

Katsuki had known him his whole life, and even though Izuku was completely different like this in most ways, over time Katsuki had realized that he still had many of the same mannerisms. Or maybe that he’d started to gain them back, but Katsuki tried not to linger on that hope too much without real proof.

Right now, Katsuki could tell that Izuku was nervous. Uneasy. It was possible that he sensed Katsuki’s unease and that was making him uneasy in turn, but Katsuki wasn’t entirely certain.

“I don’t want to leave you behind,” Katsuki said firmly, and the mention of it made Izuku’s face fall. Guilt stirred up within Katsuki, but he pushed onward. “I’ll do everything in my power not to, but if you harm anyone, then you and I can’t be together anymore, got it?”

Izuku’s eyes were a bit wide as he stared off into the distance. The gears were clearly turning behind his eyes. After a long moment, he asked quietly, “What do you mean by ‘harm anyone’?”

“You cannot bite anyone,” Katsuki ordered, making his voice as stern and grave as he was capable of. “You will not touch any humans at all or drink their blood. Ever. If you’re thirsty, you need to tell me, and I’ll take care of it.”

Izuku’s brow furrowed slightly as if he was a bit puzzled, but his gaze remained in the distance.

“Izuku, is that understood?”

Izuku nodded jerkily. “Yes.”

“If you’re overwhelmed or find that you’re losing control of your ability to not want to bite people, you’ll tell me about that too, got it?”

“Yes.”

“Okay, good.” Katsuki breathed out a long sigh, steeling himself for what he was going to say next. “Alright, I need you to answer this next one honestly. It’s very important.”

Izuku nodded once, tilting his head closer but not lifting his gaze.

Katsuki had noticed he’d been doing it more often where he wouldn’t look at Katsuki when Katsuki was looking at him. It was probably his version of submission, trying to earn goodwill by showing his lack of intent to try and control Katsuki’s mind. It probably wasn’t a good idea for Katsuki to trust it, but he did for some reason. He didn’t sense any deception from Izuku.

“How badly do you want to bite me?” Katsuki asked, eyes trained on Izuku’s torso in case his gaze snapped over.

Izuku startled, but he didn’t look over. Katsuki glanced up at his face, seeing how Izuku’s eyes were widened.

“It’s not a trick question,” Katsuki added immediately when he saw the anxiety gathering on Izuku’s face. “It’s important that I know. For my own safety, before we travel.”

Izuku shoulders rose and fell more quickly. He swallowed, his Adam’s apple bobbling with it. His jaw flexed as he visibly clenched and unclenched it. That was a habit he’d picked up that he hadn’t had before. He did it often, from what Katsuki had noticed.

“I won’t… I won’t do it,” Izuku said in a strained voice. “If… if you tell me not to and keep giving me blood to drink, I won’t do it.”

Katsuki put the lid on his stew and stood. His heart was racing with his anxiety. He knew Izuku could hear it, but it wasn’t like he could control it at all. He turned to look at Izuku, crossing the room towards him.

He saw how Izuku stiffened and froze. He was sitting back on his ass with his legs crisscrossed under him, his hands bound behind his back like usual. His gaze was averted off to the side, but it nervously darted in Katsuki’s direction and then away again as he approached.

Katsuki stopped directly on the other side of the edge of the spell limits. If his magic had formed a physical cage, he would be standing directly on the other side of the bars.

“You think you can control yourself like that?” he asked.

Izuku’s whole body had begun shaking slightly as Katsuki had approached. His eyes darted around on the far wall, but he didn’t look at Katsuki. He nodded jerkily again.

“Yes.”

Katsuki crouched down and sat back on his haunches so he was more on eye level with Izuku. “How do you know that? How do you know you won’t lose control and try to bite me?”

Izuku winced. He was breathing hard. His eyes had stopped darting around. They were locked at some point on the far wall that he was staring at. His jaw was clenched tight, but Katsuki could see the movement in his jaw as he pressed his teeth against each other harder and released it over and over again.

“You seem to be struggling a lot now and you just drank,” Katsuki pointed out.

Izuku’s expression flashed with something determined. It was so familiar—so Deku-like—that Katsuki felt something flutter within his stomach. There was that look on his face that was resolved and unstoppable. That part of Izuku—of human Izuku—that wouldn’t let anything stop him once he’d set his mind to it.

“I’ll get used to it,” he declared firmly. “I won’t do it.”

There was a stubborn set to his mouth. Katsuki stared.

“Get used to what?”

“To you. I’ve already gotten better. I’ve gotten better, haven’t I?”

“Yes,” Katsuki replied as something deep in his heart ached suddenly. He took another deep breath, steeling himself yet again for what he was about to say. He stood up, taking a few steps back in case this set Izuku off. “I asked for another reason, too, Izuku.”

Izuku said nothing, clearly waiting in tense anticipation.

“More than anything, I don’t want you to hurt anyone else,” Katsuki said firmly. “That was part of my oath. I will not allow you to drink the blood of another person or harm them in any way.”

“And I won’t!” Izuku insisted, desperation creeping in to his tone.

Katsuki took a deep breath. His heart raced with anxiety. Was he really about to do this? To offer this?

“Good,” he breathed out. Then more firmly he said, “I would be really happy if you were able to keep yourself controlled, you know. If you were able to communicate to me when you were struggling to do so and only drink my blood rather than any other human’s, I would be very, very happy.”

Izuku nodded along as he spoke, that look again settling into his eyes. He looked very determined, and it was again so Deku-like that Katsuki found the next words coming slightly easier.

“If you’re able to do that, then I’ll consider letting you bite me to drink sometimes.”

Izuku whole body tensed and he went stock still. He was so still that it was almost unsettling.

Katsuki hurried to elaborate. His heart was thundering. “We’ll have to talk about it beforehand. And figure out a way to make sure you won’t lose control and hurt me. But maybe you can bite my forearm or something. But only if you do your best when we’re traveling, okay?”

Izuku hadn’t moved, still staring wide eyed at the far wall. The first thing to move was this jaw, as he started to clench and unclench it in that new habit of his. He swallowed, then inhaled deeply through his nose.

After a long, tense pause, he breathed out. “Okay.”

Katsuki watched him warily. “Okay, what? You agree to those terms?”

“Yes.”

Izuku finally moved, and it was to move his mouth over to his right shoulder and rub at it. He shifted his shoulder forward, and Katsuki watched in confusion as he rubbed his mouth and jaw against his shoulder despite the awkward angle. He was again trembling slightly.

Katsuki was a bit unnerved by the behavior, to say the least. He wondered if this was Izuku trying to control himself somehow. If Izuku was overwhelmed by the idea of maybe being able to bite him, and so he was trying to distract himself.

Katsuki felt a sensation rush through his body at that thought, making him feel strange and conflicted. He hurried to shove himself to his feet and turn to walk further away, ignoring that feeling. He stalked over to the bags he’d brought back, grabbing one and digging through it.

“There’s one last thing,” Katsuki said as he did so. “I wanted to understand where things stood first, but I’m still not comfortable with this.”

“I’ll—I promise I’ll be good,” Izuku’s reply was immediate, but a bit muffled by his shoulder. “I promise.”

Katsuki clenched his jaw as the words sent a rush of sensation swooping through his gut. It was like a tug, a hot coil far too low in his gut. Goddammit why was his body reacting like this? He ignored it.

“Good, that’s good,” he gritted out as his hand wrapped around the item in the bag. “Still, I can’t just let you out with everything as it is now. But I wanted to talk to you about it beforehand, so you didn’t just wake up and not know what was happening.”

Katsuki stood, holding the item in his hand as he turned. He walked back over, and he saw how Izuku slowly turned his head, slowly raising his gaze only far enough to see what was in Katsuki’s hand. For a moment, he looked confused.

Katsuki rotated it in his hand, holding it up. Izuku’s eyes widened as he clearly figured out what it was. He stared at it but didn’t move or speak otherwise.

“This will help you, I think,” Katsuki explained. “At least when it comes to being close to me. It’ll take some of the stress away, and it’ll suppress your magic in general, which will make things less stressful for me.”

“Is that…” Izuku started to ask in a near-whisper.

“It’s a muzzle. So this metal part will go on your face over your nose and mouth, and the leather will secure it to your neck and head.”

Izuku blinked at it.

“It’s magic, and I’ll be securing it with magic,” Katsuki added, for full transparency. “You won’t be able to take it off on your own. So, you won’t be able to bite me even if you randomly fully lost control for some reason.”

It was an experimental bit of magic, to say the least. Katsuki had been working on it all month. He’d commissioned it from the blacksmith in town—and perhaps not-so-ethically altered his memory a bit so he wouldn’t be able to recall Katsuki’s face. Since its completion, Katsuki had spent many hours trying to infuse it with spells modified from the ones he used to contain Izuku now.

Izuku stared.

“When we travel, things are going to be stressful for me, and I need you to try to make things as easy for me as possible, okay?” Katsuki reminded him firmly.

Izuku’s lips parted, but no words came out. He closed them again, pouting his lips slightly for a moment. Then he just nodded.

“I need verbal confirmation that you understand, Izuku.”

Izuku’s face looked a bit uneasy, but his voice was firm when he replied, “I understand. I’ll be good.”

Izuku

Izuku hated the muzzle.

It was made of solidly crafted metal that fit snuggly over his face. Most of his face was covered, except around the eyes. The metal was flush with his face around his temples, eyes, and over his nose, but it sloped outward over the bridge of his nose and allowed for some room in front of his nose and mouth. It was connected to his face by leather straps that went around the back of his head and a much bigger leather piece that went around his neck and down over his shoulders, looping under his armpits. It was comfortable enough, but it didn’t so much as budge on his face or neck.

Besides the fact that Izuku felt more like the human’s damn pet than he ever had—as he was fairly certain that these things were things that went on pets—he hated how it dampened his magic. The human had majorly skimmed over that part of things.

But when Izuku had woken up with the muzzle on his face, it was clear that almost every bit of his magic was being forcibly suppressed under the magic coming from it. It was as if the muzzle was containing his teeth and his magic. He felt significantly weakened physically, and he was certain that his eyes wouldn’t be able to influence the human anymore when he was like this. He wouldn’t be able to control his mind, or anyone’s for that matter.

He’d effectively been controlled.

Izuku hated that it felt so heavy because he also felt so weak. He hated that it was so secured to his face both by the leather straps but also clearly by the human’s magic. He hated that his poor teeth that had never been able to bite anything were now officially locked away, aching and confined behind bars.

So, Izuku woke up annoyed, frustrated, and ready to do the bare minimum to cooperate. After all, he’d said he was going to do his best and then the human had still put this thing on his face. Now, he felt like he was moving with weight pulling every part of his body down. Like he was double-shackled.

Though his mood quickly changed. Because what he’d failed to consider was that this muzzle was his new prison. Meaning that he would be freed from the old one.

The human approached him and Izuku’s senses all zoomed in on him. Though Izuku’s magic was suppressed, his nature was not. He could still smell and hear and sense the human just as well as any other day.

“How does it fit?” the human asked, getting close again and crouching down onto his haunches so he was on Izuku’s eye level.

“Fine,” Izuku replied. His voice was a bit muffled, but still fairly easy to hear.

“Hmm…” The human was clearly looking at him, and Izuku stared at his neck, watching the blood moving through his veins. “Remember what I said last night, Izuku? About not harming anyone and how happy I’ll be if you don’t?”

As if Izuku could ever forget that. He’d been in near physical agony ever since. He was constantly salivating. His teeth were aching far worse than usual.

His human said that he could maybe bite him. It was all he thought about on a normal day, so naturally now that the possibility was being dangled before him, he was halfway to losing his mind with how badly he wanted.

“Yes,” Izuku replied quickly, nodding enthusiastically. Suddenly, the muzzle was no longer bothersome. Not at the reminder of what could come later. “I’ll be good. I won’t hurt anyone. I’ll tell you if I feel like I can’t control it.”

He said the words because he knew that’s what the human would want to hear. But in reality, he knew it wouldn’t be an issue. As long as his human was anywhere nearby, he was fairly certain that he’d barely even notice anyone else. He wasn’t sure why he would care in the slightest about anything else. Nothing could possibly be as interesting as staring at his human. And he wouldn’t hurt his human or lose control… especially not with the promise of drinking his blood from the source sometime.

His teeth ached painfully in protest as the thought swam through his brain but they still received no relief. The human’s blood and heartbeat filled his ears as always. He bit hard into the inside of his own lips and cheeks, the searing pain momentarily distracting him from all these things that he could no longer afford to allow himself to give into ever.

Izuku swore to any and all gods and devils that were listening that he was going to surpass his human’s expectations so thoroughly that it would blow his mind. The human would be happy and proud of him, and then maybe… maybe…

“Last thing.” The human’s voice cut through his thoughts. “Even with your magic suppressed, I don’t trust you with my name. Names have too much power. But I’ll give you something you can call me, okay?”

Izuku’s eyes widened. A name? Excitement bubbled in his chest. Since the human was a warlock, he suspected that he’d never give any name at all. But a nickname or a made-up name? Those weren’t typically any good for magic anyways.

“You can call me Kacchan.”

Outside, the air was cold and the sky was blue overhead.

For a long moment at the edge of the cave, Izuku paused and looked out at the terrain. It felt a bit strange. He’d been imprisoned in this cave for more than half a year, and he had no memories from before that. Even still, the feeling of the cold air freezing his nostrils and the sight of the trees and river in the distance and mountains all around was a familiar enough one.

He didn’t think he knew where they were, only that he’d seen this view before.

“Follow after me.”

Izuku glanced over at the sound of the human’s voice.

Kacchan.

The human called Kacchan. His human.

Kacchan was dressed for travel, his long, dark grey cloak on and a big pack on his back. He had a sword hanging from his belt, and his bow and quiver of arrows slung over his back. The human had many knives that were likely tucked away in different places. His hood wasn’t pulled over his head, and Izuku found himself momentarily captivated by how the sunlight lit up his blond hair.

Actually, just captivated by how Kacchan looked in the sunlight in general. Izuku’s eyes trailed down from his hair and were suddenly in heaven. With so much more light to work with than ever before, Izuku quickly got to work memorizing every detail of Kacchan’s face and neck, every slight difference in texture, every pale hair, every vein, every—

Kacchan started walking, and Izuku was forcefully yanked from his trance-like state. He hurried to follow.

In contrast, Izuku carried very little and had no weapons at all. He too carried a pack that Kacchan had given him, but it contained mostly human food and water—which Izuku suspected Kacchan was just making him carry because he knew Izuku wouldn’t have any use for it—and the remnants of the blood of the other humans that Kacchan had brought him the other day. Izuku had no use for those, either, but Kacchan told him he needed to have them in case of emergencies.

Izuku didn’t like the sound of emergencies. He intended to avoid them if at all possible.

Izuku also had a similar cloak on, but his hood was pulled over his head, casting the top part of his face in shadow. The muzzle effectively blocked most of his face and neck, and his cloak covered the exposed parts around his eyes and ears. The rest of his body was covered by the cloak, his clothing, and his boots. His hands were covered in brown leather gloves that Kacchan had given him. Strangely, they fit him perfectly.

The sunlight would burn him, after all.

Kacchan had explained that direct sunlight would hurt him, and that the longer he was exposed to it, the more it would hurt. Not badly enough that they had to avoid going outside during the day, but that Izuku needed to keep his skin from coming in contact with direct sunlight at all times.

Izuku had listened politely, but somehow, he’d already known that. Not that he remembered the sunlight ever burning him, but he just sensed that it would. In the same way someone could feel heat radiating off a fire, Izuku felt an energy radiating off the sunlight that he knew to shy away from. An instinct of some kind. But he let Kacchan explain it to him anyways.

As he listened to Kacchan explain, Izuku also grew even less annoyed about the muzzle. In fact, it almost started to grow on him as he realized that Kacchan had put a lot of thought into this. It was clear by how much he was explaining it all.

Was it possible that Kacchan had worried about the sun hurting him, and thus had made sure the muzzle would cover most of his skin? It wasn’t impossible to believe, despite how Kacchan never explicitly said that. After all, despite how Kacchan was a very odd creature that Izuku found difficult to understand, the human was undoubtedly kind.

Kacchan started down the mountain, and Izuku followed obediently after him.

The landscape was a colorful place of greens and blues. Even with the duller colors of the approaching winter, it was much more bright and vibrant than the gray walls of the cave. The cold wind whistled, and Izuku yanked his hood further down so it wouldn’t blow off and expose the skin of his face to the sun.

Kacchan was in front of him. The familiar shock of blond hair and sturdy set of shoulders was easily Izuku’s favorite thing to look at. Even with all the beauty of the landscape to take in, Izuku found his gaze repeatedly trailing back to him.

Izuku was both surprised and not to find there was a light, warm feeling growing in his chest as he trailed after his human down the mountain.

He was happy.

Kacchan walked quickly and in silence for a long time, and Izuku dutifully followed him for that whole time. Despite how he was weakened by the muzzle, he kept pace with Kacchan easily.

Izuku was so thoroughly enjoying not being in the cave, being near Kacchan, the sights, and the potential for biting Kacchan later that he had zero complaints at all about anything. Not even the muzzle. Even when it annoyed him, all he had to do was glance up towards the sunny sky and remember that it was allowing him to come along with Kacchan. And that Kacchan was also using it to protect him from the sun.

At the base of the mountain, they walked through a patch of forest and arrived at a path. Izuku was distracted, looking around with intrigue, but his attention was quickly drawn to Kacchan when the human spun and grabbed the front of his shirt. His expression was serious and Izuku immediately panicked.

Had he messed up already? How? He hadn’t done anything!

But Kacchan simply pulled him close, and spoke in a low, threatening tone, “We’ll be encountering humans now, Izuku. If you can’t handle it without attacking them, you will tell me immediately, got it?”

Izuku felt lightheaded and nearly giddy from Kacchan’s proximity. Kacchan was the slightest bit taller than him, his red eyes slightly above Izuku’s own eye level. Another benefit of the muzzle was Kacchan seemed to have far fewer hesitations about looking Izuku in the eye, and Izuku was blessed with the full intensity of those blood red eyes. He instinctively tried to reach out towards Kacchan’s mind—not to take full control but just to almost touch—but he found himself entirely unable.

Kacchan was also nearly touching him, with his hand balled up in Izuku’s shirt. Up close like this, Kacchan’s smell was so potent it was almost like tasting him. Izuku’s lips parted, breathing in desperately as he tried to savor that almost-taste.

Kacchan’s heart was beating and his blood was moving right there and Izuku had to clench his hands into fists as hard as he could to keep himself from reaching out to touch. Kacchan would definitely not be happy with him if he did that.

“Got it?” Kacchan hissed, shaking his hand that was balled in Izuku’s shirt for emphasis.

Izuku managed to nod, though he didn’t really remember nor care what Kacchan had said at the moment. It was probably just a reminder of the stuff he’d already promised. “Yes, Kacchan.”

“Good.” Kacchan released his shirt and turned away. “Follow me.”

Izuku didn’t notice the humans at first. Well, he noticed them in that his senses mutedly perceived them. But he was very busy at the time.

Staring at the back of Kacchan’s neck.

As they’d walked down the path leading away from the mountain, Izuku had taken up his place next to Kacchan, trailing a pace or two behind him. But without the mountain views to distract him, Izuku had almost immediately locked on his favorite view of all.

By now, a bit of sweat was trailing down the sides and back of Kacchan’s neck from the hike. Even though it was cold out, he was wearing a lot of layers and they were moving very fast. From this angle, Izuku could still admire the side of Kacchan’s neck and the veins that ran underneath his skin. Watching the sweat drip down the side of his neck, accompanied by the sound of Kacchan’s blood moving in his veins was mesmerizing for Izuku. It left him fully and happily entertained, if not incredibly thirsty and wanting.

Izuku wanted to lick the sweat off his neck. So badly. He could smell the saltiness of it and it smelled like Kacchan.

Would Kacchan let him do that? If he was good? That didn’t even require biting, so maybe if Izuku promised not to bite then—

His daydreaming was cut off as Kacchan abruptly spun to face him. His red eyes were sharpened with warning, and Izuku immediately tensed, eyes widening.

“Everything okay?” Kacchan asked. His voice was quiet, serious, and a bit stiff.

For a moment, Izuku didn’t realize what he was asking. Then Kacchan’s eyes darted to the side. Izuku realized that humans were approaching, moving down the path towards them. Izuku heard how Kacchan’s heart was racing way, way faster than usual, and he could sense his sudden fear.

Oh, right. Kacchan was worried he’d attack someone.

Izuku nodded. “Yes. Perfectly fine.”

“You’re not going to lose control?” Kacchan’s eyes were wary and suspicious.

Izuku decided being truthful might actually benefit him here.

“Honestly, I hadn’t really noticed them, Kacchan.” He let out a bit of a nervous laugh as Kacchan’s eyes scrutinized him. “I was, uh, looking at your neck.”

Kacchan didn’t seem angry or disconcerted or anything that Izuku would’ve guessed. Instead, to Izuku’s great delight, some of the wariness left his eyes and his heartrate slowed from its full-blown panic. His gaze turned more neutral and then he nodded once.

“Good,” he said as he turned to continue walking. “You keep doing that.”

Izuku’s lips pulled into a wide, giddy grin. He practically preened as his whole body tingled happily.

Kacchan was happy with him. And he wanted him to keep looking at him.

Izuku was all too elated to continue looking at Kacchan’s neck and fantasizing about licking the sweat there. Or sinking his teeth into it. Or both.

Chapter Text

Izuku

They walked all through the morning and afternoon, stopping a few times for Kacchan to drink water or eat. Izuku took this opportunity to not look at Kacchan—mainly because Kacchan could easily see him doing it and for some reason that felt sort of embarrassing when they were sitting so close and facing each other.

Instead, he looked at the other people walking past.

They’d entered civilization at one point. Now, humans of all kinds walked past in various colors of cloaks and different styles of armor and weaponry. Some rode on horseback, the clop of the hooves clacking against the cobblestone streets.

There were plenty of non-humans as well. Elves, dwarves, were-people, and giants were the most common. He spotted a few people that likely had faerie blood, dragonborn blood, and even some who he sensed were distantly descended from vampires.

Izuku spotted a few people who were obviously warlocks by their state of dress as well. Their cloaks were a good deal more vibrant than the average cloaks, with brighter colors and their distinctive emblem pressed into the gold of the clasps on their cloaks. Izuku wasn’t entirely sure how he knew these people were warlocks—the strongest human magic users—but he was certain of it.

It wasn’t lost on Izuku how Kacchan pulled his cloak over his head and faced away from those people. He didn’t question it, of course. He wasn’t willing to put any of his goodwill with Kacchan at risk.

But he was admittedly a bit curious. Kacchan had talked about his warlock studies with “Deku” in a faraway city but never got around to mentioning how things ended. He wondered now if something had gone wrong. Kacchan clearly didn’t want them to be seen by the warlocks.

Izuku also noticed that their own cloaks and even his muzzle hardly stood out at all. Lots of people wore cloaks. Some walked quickly, with hoods pulled up and heads tilted down. Many people also wore face armor or masks.

A few other creatures were also wearing what were obviously muzzles. Izuku couldn’t help but stare at them a bit longer, and the people they were with. Were they wearing them by choice or were they also required to wear them to be around others? Was it fashion or was it ownership? He didn’t ask Kacchan about that either.

Similar to when Izuku had stepped out from the cave, he felt a bit strange. Though he had no memory of this place or any of the sights, he wasn’t surprised by them. There was a feeling of having seen all this before. A familiarity of sorts.

In the late afternoon, they reached the edge of what seemed to be an especially large town. Maybe even big enough to be a city.

“You still doing okay?” Kacchan asked him as they approached.

“Yes!” Izuku reassured quickly, nodding.

It was true in that he felt no more tempted to drink the blood of anyone else than he had before. Of course, he could hear the blood and hearts of every creature they passed. It all called to him so dimly, especially with Kacchan in his field of vision.

As if each of them were a single ember and Kacchan was the sun.

Why would he ever look away from Kacchan?

Izuku did, however, feel significantly thirstier than he did this morning. It was simply just the passage of time and his constant, intense focus on Kacchan, but Izuku’s throat was starting to hurt badly, demanding relief.

He was still fine for now. He was used to it, but he’d definitely stopped looking away from Kacchan’s neck more and more as the hours ticked by. This evening, when he knew Kacchan would give him more blood, couldn’t come fast enough.

They entered the city, which was bustling with people this late in the day. People of all ages and species were intermingling, talking, moving from place to place.

Izuku stayed close to Kacchan. Kacchan had quietly ordered him to, but he would’ve done it anyways. It was harder to think past his growing thirst and getting separated from Kacchan was the last thing he wanted.

As they navigated the crowds, Izuku’s temper grew shorter. His patience waned. He was so goddamn thirsty. He dutifully continued to trail after Kacchan, of course, but he was rapidly losing the ability to think clearly.

Izuku was also so, so goddamn annoyed because the crowds meant that there were a lot of sounds and smells, and they were all constantly trying to butt in on him listening to Kacchan’s heart and blood and breathing. He couldn’t smell Kacchan as distinctly with all these other people nearby. He focused as much as he could on Kacchan, but all those other things kept annoyingly trying to interfere. Over and over and over again.

By the time they got out of the most crowded part of town, Izuku was thoroughly irritated. This place stunk of things that weren’t Kacchan and it was too loud so it was hard to be as in tune with Kacchan. He almost missed that damn cave, if only because there’d been very few distractions from Kacchan.

“How’re you doing?” Kacchan turned to glance at him, and Izuku hoped his face didn’t give his mood away too much.

“Fine.”

Kacchan stopped walking, turning fully to look at him.

Half of Izuku’s anger immediately swapped place with panic. “I’m fine! I’m fine, Kacchan. We can keep going!”

Kacchan’s eyes burned into his for a few seconds too long, and Izuku felt strangely like Kacchan could see right into his mind.

But after a long moment, Kacchan turned to continue. “Not much further, okay? Tell me if you need anything, Izuku. I mean it.”

“I will.”

Izuku continued following after him, trying to resist the growing irritation. He was under control, but he was not having a good time. He didn’t like it here. All these people were getting on his nerves.

They were getting way too close to Kacchan.

Izuku was trying so hard to be good, to just follow after Kacchan quietly and thus stay on Kacchan’s good side. He was trying so hard, dammit. He focused on Kacchan as much as he could.

It felt like his throat was burning.

Be good. Be good. Be good. He repeated in his head like a mantra. You told Kacchan you’d be good.

Izuku focused on Kacchan more and more, but his irritation from the distractions didn’t go away. And in this crowd, too many people were way too close to Kacchan. They walked past him, so often almost brushing past or bumping into him and each time, Izuku’s rage spiked.

Don’t touch him. He glared at the people around them as he followed after Kacchan.

It was getting harder to think. There was a tight ball of anger in the middle of Izuku’s being. Focusing on Kacchan helped him forget about his thirst and remind him that he’d get to drink soon, but it just shifted all Izuku’s annoyance into defensive aggression.

Too close. Izuku glared daggers at a woman that nearly bumped hands with Kacchan. He’s mine.

The woman made eye contact with him and the blood drained from her face. Then Izuku passed her, still following Kacchan, and she was gone.

Izuku followed on Kacchan’s heels. He felt so overwhelmed. He was in so much pain. Kacchan would fix it all when they got where they were going. Kacchan would help him, but he needed to be good before then. Kacchan—

A man brushed shoulders with Kacchan, and a loud, infuriated noise was wrenched from Izuku’s mouth. The man immediately startled a step or two away, shooting an alarmed, disturbed look Izuku’s way. A few other people looked over too.

Izuku clenched his hands into fists, barely stopping the instinct to grab at Kacchan and pull him away. Kacchan wouldn’t like that.

Though, Kacchan really didn’t like what he’d just done either, and Izuku noticed immediately when Kacchan stepped in between the man and Izuku and spoke.

“Sorry about him,” Kacchan said to the man, then turned to grab hold of Izuku’s cloak and yank him further away from the man. “He’s an imbecile.”

Izuku’s gaze was torn from glaring at the man to Kacchan as he grabbed hold. His eyes widened with fear.

Kacchan was mad.

It was clear by his barely controlled tone of voice and how he immediately used his hold on Izuku to drag him off the main street and into the nearest alleyway.

“Kacchan, I—”

“What the hell was that?” Kacchan barked, slamming him against the wall. “I thought you were going to tell me if you couldn’t handle this!”

Izuku’s head swam from the proximity. Gratefully, he inhaled deeply. The alleyway was right off the main street, but it was empty except for the two of them. With Kacchan crowding him against the wall, his senses were delighted as they more easily zoned in on him.

It was still hard to think, but at least he wasn’t nearly as irritated. No one was too close to his human anymore. His human was right in front of him. No one was going to take him. They weren’t going to get separated.

A bit delayed, Izuku replied, “I—I can handle this!”

“How was that handling this?!”

“I didn’t touch anyone! I didn’t bite anyone… or try to!”

“No?! Then what the hell was that?!”

Izuku felt tears burning his eyes. Kacchan was so mad. Had he messed things up despite how hard he’d been trying?

“It wasn’t like that! I didn’t want to bite him!”

“I would’ve gone around the town if you’d told me you couldn’t handle it! You promised to communicate with me if you couldn’t control yourself!”

“And I will! I can control myself!”

“Then what the hell was that?!”

“He touched you!” The words burst out of Izuku’s mouth a lot lower, rougher, and angrier than he’d planned to.

“Hah?!” Kacchan raised an eyebrow, scowling at him in confused disgust. “What the hell are you talking about?”

“He…” Izuku was heaving in breaths as his anger came back to him. His eyes darted over to the main street off to the side that they’d come from. He glared even though the man was far away. “…touched you.”

His entire being was screaming at him to grab Kacchan and drag him further from the crowds. He wanted to sink his teeth into his neck, to lie on top of him so no one else could get him, to keep him all to himself. He was so thirsty and only Kacchan could help. Like hell would he let anyone else touch his human.

Kacchan stared at him with his mouth hanging open. Then he scoffed. “Are you fucking with me right now?”

“No.”

Kacchan looked completely astonished for a moment. Then he snorted loudly. “Izuku, they barely touched me while they were brushing past.”

Izuku frowned, looking off to the side.

“Oi!” Kacchan grabbed hold of the muzzle and used it to yank Izuku’s face forward. “This is important! You can’t just, like, growl at people, Izuku!”

Izuku’s shoulders slumped as he peered up into Kacchan’s angry eyes with his own shining with the beginnings of tears.

“Kacchan, I didn’t really mean to. It just happened.”

“So you can’t control yourself?”

“No, I can! I just—” Izuku felt dread creeping in. He could feel Kacchan’s distress and anger and fear, and he didn’t like it. He’d been trying to protect Kacchan, not make things worse. “I didn’t hurt anyone! I didn’t want to, either! He just got too close, Kacchan!”

Kacchan stared at him intensely for a long moment, then he closed his eyes and breathed out a long breath. “Fuck, okay.” He opened them again, looking at Izuku so seriously that Izuku’s knees felt a little shaky. “Okay, to be clear, you didn’t try to attack him because you wanted to bite him, it was only because you thought you were protecting me or something?”

“I didn’t try to attack him at all! I just made a noise!”

“Yeah, a fucking weird, scary noise!”

Izuku frowned, feeling even more embarrassed. He averted his gaze downwards, trying to keep from letting his eyes gather any more tears. He didn’t want to cry right now.

“Answer me, Izuku. It was just because you thought you were protecting me, not because you wanted to attack them or drink their blood?”

“Yes,” Izuku grumbled unhappily. “It was just because they got too close to you.”

Kacchan clicked his tongue in annoyance, shoving away from Izuku and taking a few steps back. He put a hand up to rub at his eyes aggressively.

Izuku didn’t move, watching him fearfully. How did he make Kacchan understand how hard he was trying? Everything was just so overwhelming, and he just wanted to be with Kacchan.

The silence stretched for a long moment as Izuku waited for Kacchan to say something. He could sense Kacchan’s emotions and confliction, and he just wanted to make him feel better.

“I—I didn’t know that you wouldn’t want me to do that,” Izuku said. “I didn’t realize. I didn’t think about it, really. I’m sorry, really, Kacchan. It won’t happen again.”

Kacchan let out a long, angry huff of a sigh. Still rubbing at his eyes, he said, “In cities like these, where all kinds of beings are allowed, there are rules around fighting. In the city center like this, they’re very strict. Causing a scene is the fastest way to get us in a whole lot of trouble, do you understand, Izuku?”

As he spoke, Izuku shrunk back against the wall again. “Yes, I’m sorry.”

“We’re also not locals and have no allies here,” Kacchan went on, voice stilted. “I’m sure you’ve noticed, but there aren’t any other of your kind here, Izuku. We can’t afford drawing attention to ourselves, negative or otherwise. Do you understand?”

“Yes, I do. I—I’m sorry,” Izuku quickly stammered out his apology as his shoulders slumped further. “It won’t happen again.”

The noise had been completely unintentional. His brain had just blacked out and screamed that Kacchan was his human and then he’d been trying to get the man away from him. In retrospect, it was not a very rational reaction, but he didn’t exactly have a lot of extra space for rational thought at the moment.

Izuku swallowed, wishing he had any way to soothe his burning throat and aching teeth. As it was, he knew the muzzle wouldn’t come off until they got to their destination. To do that, he’d have to just tough it out until they got there. And they’d get there faster if he could handle a few people brushing against Kacchan now and then.

“Can you promise that?” Kacchan pulled his hand from his face and leveled Izuku with a scrutinizing look. “We’re in a city, Izuku. People accidentally brush each other all the time. You’re not an idiot, so surely you can tell when someone is just walking past and not actually a threat?”

“Yes. I can tell the difference,” Izuku said earnestly. “I’m sorry, Kacchan. It won’t happen again. I promise.”

What he didn’t say was that while he could tell that the person had just been walking past, that hadn’t exactly mattered. They’d still gotten too close. But he would have to keep it in and try to let it go when people did that, or Kacchan would be mad.

Kacchan nodded slowly. He glanced out towards the street. Izuku could sense his unease and fear that’d spiked back up, and his shame only worsened.

“I promise, Kacchan,” Izuku repeated. “Now that I know, I won’t do it again.”

Kacchan stared him down, and Izuku stared back, trying not to despair about his small slipup. He couldn’t afford to do that again. He needed to be good if he was ever going to be allowed to bite Kacchan.

“Okay, let’s go,” Kacchan said. “Stay close to me.”

Izuku had no arguments with that.

Katsuki

Katsuki really hoped he wasn’t making a horrible mistake.

The path through the town was much quicker than navigating the terrain around it. Since Izuku had been doing so well, he hadn’t seen any issues with just cutting through.

He’d sensed Izuku’s growing irritation as the minutes ticked past, of course. Once they’d left the cave, it hadn’t taken him long to notice that his bizarre hyperawareness of Izuku hadn’t faded. He could still sense Izuku’s state of being and emotions to some degree in a way that was definitely not normal. It was very odd, but he didn’t have time to dwell on it now.

When Izuku had made that snarling, growling noise at the stranger, Katsuki had been convinced for a split second that Izuku was going to go all mindless with bloodlust again. Normally, he only made sounds like that when he was half out of his mind with a desire for blood.

But Izuku had seemed relatively in control when he’d hauled him into the alleyway. And apparently it was just Izuku being… possessive over his food or something? Katsuki hadn’t figured it out yet, but from what he could tell and sense, Izuku was getting thirstier but still only for Katsuki’s blood. It just seemed like Izuku was being territorial rather than being blindly hostile or out of control.

Still, Katsuki hadn’t even known that that was something vampires did. Though he supposed they hardly had a normal situation going on here. Usually, vampires attacked and drained their victims of blood all in one goal. They probably weren’t used to sharing.

If he thought about it, he had to admit it made a lot of sense that Izuku would be extra cautious about his only food source. It just really hadn’t occurred to him before now, and the extent of it was strange to him.

Katsuki just didn’t know what to do with any of it, but there wasn’t anything to be done right at this moment. It was probably just something Izuku would have to get used to, as this was their first time out in civilization together since Izuku had become a vampire.

For now, Katsuki just tried to avoid brushing against anyone, for everyone’s sake.

They’d have to stop somewhere for the night soon. The sun had already started to set. Katsuki got the feeling that Izuku was pushing himself out of a desire to not cause problems and to prove himself, but that just made Katsuki more anxious. He knew Izuku was thirsty, both because he had to be by now, but also because he could sense Izuku’s agitation and discomfort practically radiating off him.

Out of an effort to make things easier for Izuku, Katsuki cut away from the main roads. He knew of a place where they could stay for the night. This would both get them there quicker and hopefully make things less stressful for Izuku.

This part of town was darker, full of narrow alleyways and was generally far less busy. Many of the buildings were more run down, and there were far more locals than travelers now.

Katsuki found himself growing relieved as they approached their destination. The sun had set far enough that it was growing darker in the city, leaving the streets and alleyways lit more and more by irregularly placed lanterns.

But it seemed that nothing could go too smoothly, because they were cutting through a wider back alleyway when someone turned the corner and clipped shoulders with Katsuki. Hard.

Katsuki’s shoulder smacked fully backwards, and he nearly stumbled from the unexpected movement. He was immediately very annoyed. The guy was a big brute, and it was clear he’d done it on purpose. If he’d been alone, maybe he would’ve engaged more and tried to teach this guy some manners… but he wasn’t alone.

Izuku made the beginnings of a low noise in the back of his throat that was abruptly cut off as Katsuki turned and shot him a warning look.

“Watch where you’re going!” The man snapped rudely.

“You bumped into me, jackass,” Katsuki said as he kept walking, glad that he sensed Izuku on his heels rather than lunging at the guy.

“What did you say?” The man didn’t leave it, turning back to face him. At the same time, two equally large men came around the corner. Katsuki stopped abruptly as they converged on them, sensing more than seeing that Izuku was still right behind him.

As Katsuki glanced at the newcomers and took a second look at the guy who’d run into him, it was immediately clear that these weren’t men at all. They were too large. Their heads were too blocky and their features too squished. The first of them had been the smallest, but now with the other two, it was easier to see.

They were likely had troll blood or some kind of were-people. Maybe giant blood, if they’d all missed out on inheriting the being-super-tall part. Katsuki couldn’t fully tell what they were, but they were too large to be fully human.

Shit. Katsuki thought as he snatched for Izuku’s arm and yanked him behind him. Not good.

Mainly not good because Izuku had growled at someone just bumping into him. Would Izuku lose it when people were more actively threatening him? At least they were out of the city center and they hadn’t actually started this confrontation, but it still wasn’t a great idea at all.

He didn’t care if Izuku thought he was in control, the snarl he’d done had effectively unsettled him. He wasn’t sure if Izuku could control himself, if he was thirsty and being territorial. If it was all instinctual, how could Izuku stop it?

No matter if these brutes started it or not, if Izuku tore them apart that would be very bad. It would be bad for a lot of reasons, but not least of all was that Izuku had made Katsuki swear to not let him hurt anyone. Katsuki knew that Deku—human Izuku—wouldn’t be able to live with himself if he killed anyone. It didn’t matter if Izuku never recovered his memories, because that knowledge enough would burden Katsuki for the rest of his life.

The muzzle suppressed Izuku’s magic and weighed him down significantly, but Katsuki knew it wasn’t a perfect fix. Izuku was probably still stronger than all three of these guys combined. He couldn’t let Izuku attack them.

Not good. Katsuki glanced between the three attackers. He hurriedly backed up into the wall with Izuku pinned behind him, looping one arm behind his back to hold tightly at Izuku’s shirt right over his abdomen. His other hand grasped the hilt of his sword. He tried to will Izuku to stay put, hoping his death grip on Izuku’s shirt did the trick.

“Let’s not make a big deal out of this,” Katsuki said, glancing back and forth between the three massive people converging on them. “Just let us go on our way.”

“Why don’t you apologize for bumping into me, and maybe we’ll let you go?” the first one—who Katsuki decided to call Brick Head because of the especially brick-like shape of his head—said with narrowed eyes.

Katsuki tensed. He could feel how Izuku had started shaking ever so slightly. With his back pressed to Izuku’s chest, he could feel the rumbling that kept stopping and starting, and the low noises accompanying it. And he could sense it radiating off him in waves…

Izuku was angry. Very, very angry.

Katsuki was angry too, because these jackasses had bumped into him and were still trying to make him apologize. Maybe if he were a less proud man, he would’ve done it easily, but he found the words just too difficult to say. He didn’t want Izuku to attack, and he wanted to get out of here, but he just didn’t have it in him to let these bastards walk all over him.

“You know you ran into me,” Katsuki snapped. “So just move and let us go.”

Brick Head chuckled, grinning cruelly and showing off many yellow, crooked teeth. “Oh, we won’t be—”

He took a step forward, and Katsuki didn’t have time to react before Izuku let out a very inhuman-sounding growl. It raised the hair on Katsuki’s arms, shot ice down his spine, and effectively drew all three brutes’ attention to Izuku.

“Izuku, calm down.” Katsuki turned his head and ordered gruffly over his shoulder.

Izuku’s growl cut off halfway, but he was still breathing hard as he seethed loudly. Katsuki felt now how Izuku’s hands were fisted in the back of his cloak and shirt, pulling him back into his chest.

“Control your mutt if you know what’s good for you, human,” Brick Head ordered.

That gave Katsuki pause. He turned back to face the three aggressors. They were all eyeing Izuku with various levels of annoyance or disgust… but no fear. They were still hanging back, but not nearly as far as they should be.

“Mutt?” Katsuki’s eyes darted around at each of them.

Mutt was a derogatory term most often used for were-people or half-humans. Of which Izuku was neither.

“Yeah. What the hell even is that thing?” Brick Head narrowed his beady eyes at Izuku.

Izuku responded with a snarl low in his gut. Katsuki twisted his hand where it was gripped on Izuku’s shirt behind his back, pressing his knuckles into Izuku’s abdomen in an attempt to keep him from moving.

Katsuki eyes darted around at the attackers. Giants weren’t known for being the smartest, not even half-giants, but they had incredibly good noses. Trolls were the same way. Most were-people had senses more advanced than the average human as well. No matter what these guys were, Katsuki found himself a bit surprised as he realized.

They didn’t know Izuku was a vampire. They couldn’t tell.

It made a bit of sense. Vampires were notoriously elusive and deadly. They also had a reputation for being a bit haughty in general as it wasn’t very common that they would minge with other species. It was practically unheard of, really. Additionally, they were a good deal stronger and faster than most other beings, and their bloodlust and mind control deeply unsettled most other species.

Most people had never met a vampire and never would. Most people who did, didn’t live to tell the tale. It seemed that these guys had never encountered one, as they had no idea what Izuku was.

“It’s best for us all if you just let us go on our way,” Katsuki said, staring Brick Head down as Izuku’s low snarls and noises of frustration continued to start and cut off over and over again. They were getting louder, and Izuku was getting more agitated, and Katsuki was trying not to freak the fuck out.

Brick Head scoffed. “Am I supposed to find that intimidating, human? I’ve had little mutts like him for breakfast, and I’ll gladly have you too—”

Izuku let out a loud, infuriated growl of some kind, and Katsuki’s eyes widened as Izuku’s arms were suddenly wrapped around his torso, yanking him backwards so hard he almost lost his footing. Izuku had his right arm across his upper chest, with his hand over Katsuki’s thundering heart, and he was using his grip to yank Katsuki back into his own chest harder. His other arm was wrapped lower, around Katsuki’s abdomen, effectively trapping him in place.

Izuku was slightly shorter than him, but he’d jerked Katsuki back and down slightly enough that his chin now jutted over Katsuki’s shoulder.

“You can’t have him.” Izuku’s voice was low, deep, and enraged. Katsuki nearly shuddered from the sound of Izuku’s voice like that. He didn’t really sound like himself at all, and he didn’t sound remotely human either. “Fuck off if you know what’s good for you.”

It wasn’t just the timber of his voice. There was that cadence of his voice that made it sound so strange. It set Katsuki’s hair on end, lighting fear up along his spine. The muzzle effectively suppressed his magic, but in that moment, Katsuki wondered if it was still seeping through into his voice.

The metal of the muzzle on Izuku’s face was currently pressed hard into the side of Katsuki’s neck and face. His hands were holding Katsuki so tight that it hurt, and Katsuki’s fight-or-flight was suddenly going wild all over again… and not because of the three aggressors in front of him.

“Izu—” Katsuki managed to hiss out through gritted teeth as his hands pulled uselessly at Izuku’s suddenly-iron grip.

“What the hell?!” It seemed Brick Head did have some survival instincts, because he took a step or two back. His silent but equally dumb friends did as well. “What are you?”

Katsuki swallowed, trying to breathe despite the crushing, inhuman grip Izuku had over his torso. He glared in the giants’ direction. It felt like his ribs were fucking breaking, but he managed to snap, “Get the hell out of here.”

The giants looked appropriately uneasy, but apparently their stupidity won out in the end.

“Just because you didn’t train your mutt doesn’t mean we’re scared of him,” Brick Head replied, appearing to shake off his fear and start to act tough again. “We run this part of town, human. Don’t think you can come here, shoving people around, and thinking you can get away with it.”

Katsuki distantly wondered how the hell they could so casually say such messed up things, especially when people could certainly called them untrained mutts if they wanted to. But it wasn’t important at the moment.

“We’re just passing through,” Katsuki said through gritted teeth, trying to pretend his ribs didn’t hurt like a bitch and like his knees weren’t shaking. He was all but clawing at Izuku’s arms now, but it was doing nothing. Izuku was breathing loud, angry huffs in his ear. “And for the last time, you bumped into me. Now get out of here!”

Izuku was going to lose control. Katsuki could feel it. He just didn’t know what that would look like, and he really didn’t want to find out. He could feel Izuku’s anger radiating from him like some sort of beast, and he was terrified that Izuku would fly into some sort of blind rage that he’d be unable to control.

Especially if he passed out. With how Izuku was, probably unintentionally, making it so he couldn’t breathe, that was all too quickly becoming an option. His head was already feeling a bit light. And if he passed out, then they were all fucked.

“Izuku—” He hissed out as the metal of the muzzle bit further into his neck. “You’re—”

You’re hurting me is what he’d been going to say, but he was again cut off by Brick Head.

“Still no manners from you, human,” Brick Head grunted. “Maybe we really do need to teach you a lesson. Humans are always going around thinking they’re better than everyone. Maybe we put your rabid mutt down and then maybe cut you down to size and—”

Brick Head took a step forward, and then Izuku was moving. Even with his magic suppressed and being weighed down, Izuku moved almost too fast to see. He shoved out from behind Katsuki and lunged for the attacker almost faster than Katsuki’s reaction time could handle. Katsuki barely reacted fast enough to catch the strap on Izuku’s pack and yank him backwards.

“Izuku, no!” Katsuki barked, hurrying to grab one of the muzzle’s leather straps on the back of Izuku’s neck and try to yank him back more.

Katsuki was breathing hard from lack of air, and his ribs hurt bad enough that Izuku might’ve accidentally fractured a few of them. Izuku was strong. Katsuki dug his heals in, surging forward and wrapping an arm around Izuku’s upper body to try and hold him that way.

But Katsuki was momentarily distracted by a weird crackling sound and the recognizable feeling of magic simmering powerfully against his skin.

A second later, he realized Izuku’s hand was gripping at the outside of the muzzle near his jaw, yanking hard at it. Izuku was pulling at it so hard that it was actually moving, the magic snapping and protesting as he did so. Izuku’s own fingers were getting torn apart by the magic, his iron flesh ripping and peeling back, but Izuku didn’t even seem to notice. He continued to pull at it, a noise somewhere between a growl and some sort of shout was ripping from his mouth.

Katsuki stared in bewildered, stunned horror. The muzzle gave a bit, shifting further on Izuku’s face, and then Katsuki saw it.

From under the mask where Izuku was trying to tear it off, dark green tendrils that were almost black were spreading under his skin in crooked lines. His green eyes were glowing ominously.

The hell…?

Katsuki was broken out of his horrified daze when Izuku’s sounds transitioned into words that sent a chill down his spine.

“I’ll make you tear out your own teeth for threatening to eat Kacchan,” Izuku threatened lowly, shifting his hand up to grab at where the metal connected to the leather straps that went behind his head. He pulled, and the entire thing shifted away from his face. “I’ll make you tear out your own fucking eyes so you can’t ever look at Kacchan ever—”

“Izuku, calm down!” Katsuki shouted. He tried to make it sound like an order, but his words were strained from his terror. His hand wrapped around Izuku’s wrist, yanking on it. “Stop doing that! Now!”

Izuku froze, his hand and arm stilling.

“What the hell?!” Brick Head said in the background. His buddies said something similar. Katsuki barely registered any of it.

Izuku’s hand and arm weren’t moving but immediately started trembling badly. Katsuki gripped his hand as tightly as he could, ignoring the primal terror flooding his system and putting his mouth right next to Izuku’s ear.

“Stop, Izuku!” Katsuki ordered, growing desperate. “I’m fine, okay?! Let go! Stop trying to tear it off!”

Izuku immediately made a snarling, unhappy noise. In his response, his voice was still low and off, inhuman sounding. “They’re trying to attack us, Kacchan.”

Katsuki glanced up at the aggressors, who all—despite their tough-guy talk—had backed away and were watching with disturbed curiosity. He felt a flare of rage. They needed to leave. They were pieces of shit, but like hell would he let Izuku become a murderer because of their idiocy.

“Get the hell out of here!” he snapped, at his wits end. “Unless you want to fucking die!”

The attackers had finally seemed to grasp at least that Izuku was no ordinary mutt. They grumbled some excuses as they went—probably for why it was fine to run away like cowards—and disappeared around the corner.

Izuku growled animalistically, going to surge forward. He started to shout, “Don’t think you can just—”

Katsuki pulled himself more flush into Izuku’s back. Now that they were gone, all he had to do was defuse the situation somehow. He slapped his hand over Izuku’s eyes, his other hand still holding his wrist that was holding onto the muzzle. He pressed his head into the side of Izuku’s, still speaking right in his ear.

“Izuku, listen to me!” He ordered, desperation making his voice a bit strained. “You can’t go after them!”

Izuku stilled again, shaking. He was spitting mad. “Kacchan, they were gonna hurt us.”

“I know, I’m sorry! I’m sorry I got you into this, but—”

“No!” Izuku spat, yanking free from Katsuki’s grip way too easily and started forwards. “I mean, they were going to hurt you! They can’t just—”

Katsuki didn’t have time to think. He pulled a knife from his belt and sliced open his palm before Izuku could even round the corner in pursuit.

Izuku froze in his tracks, abruptly cutting off his own sentence. His head whipped around to look at Katsuki’s hand, now pooling blood in his palm.

Though he’d let go of the muzzle, those strange, dark lines were still running under his skin under the mask and his green eyes still glowed. They were both fading more by the second as the muzzle shifted back into place, but those glowing green eyes still shocked Katsuki down to the very core of his being as they locked on the blood on Katsuki’s palm.

Katsuki stumbled back into the wall as the instinctual terror flooded his system tenfold. He might’ve made a deadly mistake.