Chapter Text
Katsuki is sitting on a couch in the common room with his dumbass entourage when he gets a text from an unknown number. All it says is:
‘Recovery Girl’s office. Now.’
Because he’s feeling merciful (and a tiny bit lazy) he blocks the number and moves on with his life. Thus giving whatever poor bastard who dared to boss him around like that, not even to his face no less, a second chance at life. Congrats, shitty extra. You just had a near death experience.
A moment later Kirishima’s phone goes off and he rushes to answer it like his life depends on it. Must be his mom or something. He hears at least one ‘yes, sensei’ and his brow raises, curiosity piqued. When Kirishima hangs up he turns to Katsuki with a worried frown. “Uh, Bakubro. That was Mr. Aizawa. He says you need to go to Recovery Girl’s office right now.”
Oh. Whoops.
Wait, Deku…
He’s up and off the couch in half a second, out the front door in two more. The moment he’s outside he uses his quirk to move faster and get across campus. A million possible scenarios are going through his mind as he hurries to his destination but above all is one thought: guess the cat’s out of the bag now.
When he arrives at the building Aizawa and Recovery Girl are both waiting in her office for him, neither one looks very happy. Katsuki can’t really tell if Aizawa seems particularly judgemental today or if he’s just more tired than usual.
Both. Probably both.
“Is he okay?” Is the first thing out of the student’s mouth.
“That would depend on your definition of okay,” Recovery Girl answers primly. “But he is not in mortal danger at the moment.”
Katsuki’s shoulders slump in relief. “Okay, so what’s with the cryptic fucking message then?”
“Language, young man,” Recovery Girl chastises and Katsuki just rolls his eyes.
“As you apparently know, Midoriya is scheduled to spend the next three days waiting out his heat in U.A.'s Heat and Rut dorm. Which normally is more than secure enough to withstand anything a heat-crazed omega or rutting alpha could throw at it– even the hero students,” Aizawa begins to explain, tired and obviously annoyed. “There are a few assumptions we generally make that lead us to believe these dorms will be secure enough.”
He raises a hand and lifts one finger. “One, that the student in question only has one quirk, “ another finger goes up, “that the student’s quirk isn’t some special russian nesting doll quirk gifted to them by the previous Symbol of Peace,” another finger, “and most importantly, that the student hasn’t found their mate and already initiated a pre-bond.”
“...sounds like you should do a better job of preparing for the unexpected,” Katsuki comments, risking his own brush with death by the look on Aizawa’s face.
“Let me be clear,” Aizawa stands up straight and locks eyes with his second most problematic student. Well, maybe he’s the most problematic now that they’re basically a packaged duo. “Pre-bonding is dangerous and against school policy. You had to have broken multiple school rules to make this happen, Bakugou Katsuki. I could expel you right now.”
“Okay,” Katsuki squares his shoulders, “is that what this is then?”
It’s silent for a moment before Aizawa crosses his arms over his chest again and leans against the counter. “No. Not until we can deal with you both together. It takes two to break these rules. However, you’ve made one hell of a mess and you’re going to have to clean it up.”
“What the fuck do you mean? What’s wrong with Deku, anyways? Why am I here?” Katsuki demands, sick of beating around the bush.
“Well,” Recovery Girl speaks up. “Currently, he’s in our most heavily fortified heat room –which he has already damaged quite thoroughly– and is heavily sedated. I can’t guess how long it will last given his metabolism and sheer determination to get to you, though.”
“Get to me?”
“Mhm,” she nods and clicks around on her tablet. “He started showing signs of agitation abnormal from the usual heat symptoms. He’s had plenty of heats here in his last two years so we had plenty of data to work with. Within four hours he had shown signs of becoming feral– which was extremely concerning given the circumstances. I was half worried some horrible quirk had gotten a hold of him. By hour six I decided to go inside the room to assess him in person and he…well, he did not take kindly to another omega entering his nest. I’m quite thankful I always go in with a tranquilizer.”
“So, what, he’s been knocked out since?” Katsuki wonders.
“Not at all,” Recovery Girl shakes her head. “He stayed out for about thirty minutes that time, which was about an hour and a half less than he should have. He both passed out and awoke saying your name– or your childhood nickname, to be specific. We were quite confused but assumed maybe something had triggered him to make him feel unsafe and that he was desperate for the comfort and safety of a lifelong familiar face. I had my suspicions though so we tranquilized him again, took some samples, and moved him to a more secure heat room so that when he awoke he would have less chance of escaping and putting himself in danger.”
Katsuki’s frowns, “what do you mean ‘samples’?”
“You see, Young Bakugou,” Recovery Girl turns her tablet around to show him a bunch of lab test results that make zero sense to him. “Alphas and Omegas release varying hormones throughout different stages of bonding. These test results show extremely high quantities of a pre-bond omega hormone in Izuku’s slick and blood. If I had known about this beforehand, I would have never under any circumstances let him go into that room without you.”
Katsuki’s scowls, the expression somehow slightly sheepish as he glances between his teachers. “So…what am I supposed to do?”
“Originally,” Aizawa takes over again, “when Recovery Girl alerted me to the situation we decided the only thing to be done at this point was try and let Izuku ride it out alone. He’d already gone feral and we couldn’t justify risking another student’s safety. However, since this discovery we’ve had to sedate him twice, each time using more medication than the last and only getting a fraction of the downtime out of him. Recovery Girl is worried the amount we may need to continue this could be detrimental to his health.”
“Okay, so he’s feral, but he’s locked up so why keep sedating him if it’s bad for him?” Katsuki asks, a part of him –the Alpha part– struggling to think logically over the desperate need to see his omega, to make sure he’s safe.
“Did you miss the part where Recovery Girl mentioned he’s already tried to break his way out of the building? He’s feral and willing to use every tool at his disposal to get to you. Including One For All,” Aizawa explains, pinching the bridge of his nose. “At this point, if we don’t give him what he wants he’s probably just going to topple the entire building, hunt you down, and take what he wants anyways. At least we can save the school some money this way.”
Katsuki is quiet for a moment, processing it all. He’s a little offended that the school is willing to throw him to the proverbial wolf but he’s also plenty confident in both his own abilities and his faith that Izuku would never hurt him. Despite all the concern and drama, the situation seems pretty simple.
“Okay.”
Aizawa and Recovery Girl stare at him for a moment.
“Okay?” Aizawa echoes. “That’s it? Just, okay?”
“Yeah? What the hell do you expect me to say? I’m not scared of little Deku.” Katsuki shrugs, because he isn't. Hasn’t ever been. Knows he won’t ever be.
“I see.” Aizawa glances at Recovery Girl who only shrugs in response. “He’s feral, Katsuki. He may not recognize you at first. You’ll need to keep your guard up. Even if he does realize it’s you, he’ll probably stay feral the entire time. Who knows what he’ll do to you.”
“Tch,” Katsuki smirks, “you think Deku, my Deku, won’t recognize me? Yeah fucking right. Like I said, I’m not scared of him. Let’s go.”
“Your Deku, huh?” Aizawa shakes his head, 1,000% done with these problematic kids. “Fine. You’re signing these consent and release of liability forms first, brat.”
“Whatever, hand me a pen.” He signs, doesn’t even bother reading them beforehand. “Now take me to him.”
“Oh, dear.”
-
Even as they walk up to the building, Katsuki can tell that Deku is awake. The room must be on the back corner, top floor, because that’s the room with a bulletproof window already cracked and he can see glimpses of green lighting inside. They walk a little faster upon seeing it.
By the time he’s outside the thick steel door he swears he can almost hear Deku growling through the soundproofing. The growling might just be his imagination but the pounding against the door is definitely real.
Aizawa turns to him. “We’re going to open the door just a crack. Step inside immediately. We’ll give you twenty seconds to assess the situation and make your final decision. After that we’re closing and locking it again. Understand?”
“Got it,” Katsuki nods his head, adrenaline pumping. It isn’t fight or flight. He can already get a hint of Deku’s pheromones and he’s absolutely ready to fuck.
The door opens and before Katsuki can even take one step a scarred right hand reaches through and yanks him inside. Before he even knows what’s happened he’s shoved into a pile of blankets and pillows, looking up to see Deku standing between him and the door. Deku has his back to him, settled into a fighting stance and growling viciously at the door where their teachers stand.
“I’m good,” Katsuki calls out to them, “close the fucking door.”
“You have ten more seconds, kid. You can still change your mind,” Aizawa calls back and Deku growls louder, taking a step forward.
“I said I’m fine. He’s not going to hurt me. But he’s going to kill the both of you, and then fucking cry about it later, if you don’t close the god damn door!” Katsuki yells back.
Either enough time has passed or they’re finally listening to him because they do, indeed, close the door. Katsuki feels a small shiver run down his spine as he hears the multiple heavy locks secure from the outside. He’s trapped with the nerd now, for better or worse.
“Alright you little shit, settle down,” he calls out, eyeing Izuku critically as the omega turns around to look at him. He’s naked, which makes sense. He probably put his clothes into his nest first thing when his heat set in. He’s watching Katsuki like a predator now and honestly, the look is kind of doing it for him. “I’m here. That’s what you wanted, right? Greedy brat.”
“Mmm, alpha,” Izuku’s demeanor suddenly flips, his usual bright and sincere grin lighting up the room as he hurries over to Katsuki. The little omega immediately tugs his clothes off of him, presses a quick kiss to his cheek before he sets about carefully adding Katsuki’s contributions to the nest around them.
“Hmm, good nest?” Izuku says, turning his wide, green eyes on Katsuki again once he’s finished. Between the pheromones and the whiplash, it takes Katsuki a minute to realize Izuku is asking him a question. Asking for his alpha’s approval.
“Excellent nest,” he answers, and smirks at the pleased little shiver he receives in response. “The best nest, made by the best omega.” He can see what his words do to Izuku, or maybe it’s just his voice. Either way Izuku’s eyes are becoming hooded, his pretty pink lips parting. “Be a good boy and c’mere,” he opens his arms and a moment later has a lap full of pleased omega.
“Kacchan,” Izuku sighs happily, “my alpha.” The omega immediately starts rubbing his cheek on every inch of skin he can, grumbling about the smells of their teachers and classmates that cling to Katsuki since he hadn’t been able to shower before coming in.
“Mhm, all yours, baby,” Katsuki assures him, using his hands to scent Izuku in return. “How are you feeling?”
“Hot,” Izuku replies, still stuck in one-syllable mode apparently. He’ll probably remain some level of feral until the heat passes. Katsuki honestly can’t say he minds. It’s cute and pleases his alpha beyond measure.
“You didn’t hurt yourself trying to find me, did you?” Katsuki insists, checking for injuries as he runs his hands over every inch of Izuku’s skin.
“No,” Izuku shakes his head before burying his face against Katsuki’s neck. “Good omega. Strong omega.”
“Even strong omegas can get hurt, dumbass,” Katsuki sighs, having trouble focusing on his important task as Izuku begins to grind his little cock against his thigh. “What do you need, baby?”
“Fuck me, alpha. Need your knot,” Izuku tells him without a second of hesitation as he grinds his cock harder into Katsuki’s thigh.
“Oh yeah?” Katsuki smirks. “I dunno, maybe you should put in some work for it.”
“Good omega!” Izuku argues, sitting back appalled at the suggestion he hadn’t already earned his alpha’s cock. His nest was excellent! He’s the best omega!
“I didn’t say you weren’t good,” Katsuki corrects even as Izuku begins to growl at him. “I said maybe I want you to work for it. Maybe I want you to take it.”
“Alpha,” Izuku growls in warning, little omega canines on full display as he narrows his green eyes into a heated glare. “No games. Fuck me.”
Katsuki’s responding grin is damn near as feral as his mate is. “Make me.”
One slow, crystalline moment passes before suddenly Katsuki is on his back. He immediately tries to fight it, he meant it when he said he wanted to make Izuku work for it. Let the little brat work some of the pent up fight and frustration out of his system. “C’mon, little omega, you’ve gotta do better than that.” He comments as he rolls them until Izuku is pinned beneath him. He teases the omega by rubbing his cock against his hole a few times before he pulls back and away.
Izuku whimpers and then snarls, coming right after him. It’s not too different from when they spar except the unspoken rule is that no one can leave the nest and quirks are not permitted. Katsuki knows that if he damages anything in the nest around him, his omega may actually murder him. A good alpha respects the nest. A bad alpha, when dealing with a feral omega, might not leave a damaged nest alive.
Eventually Izuku gets fed up with the game and really comes at him. Katsuki isn’t as used to fighting in close quarters like this and he’s also not out of his mind in rut the way Izuku is in heat, so the omega eventually manages to pin him down and press his sharp little teeth to his jugular.
Katsuki laughs, high on the adrenaline and pride he feels for his omega. He really is strong. The best. “You win,” Katsuki tells him, “I submit.”
Izuku pulls back to smile at him but the smile isn’t one Katsuki has seen before. It’s almost familiar in the sense that he’s seen in the mirror before. Confident, satisfied, almost cruel. It’s foreign on Izuku’s face but he can’t say he doesn’t like it.
“Mine,” Izuku tells him, pushing Katsuki’s hands above his head and pressing his wrists together. “Stay,” he orders and when Katsuki moves one hand to test Izuku’s limits the omega snarls at him again. So, he stays. Enjoys the pleased little hum Izuku gives him for it.
From there Izuku begins to explore his body with his scarred hands, gentle lips, and curious little tongue. Katsuki knows it’s a part of his heat, the little omega doing one last final, and thorough, check to make sure this alpha meets his standards before risking carrying his pups. That doesn’t make Izuku sucking his nipples or massaging his balls any less hot, though.
“Good, alpha,” Izuku praises him as he squeezes Katsuki’s biceps and pecs, runs his fingers along his stomach and down his strong thighs. He sees a strong, virile alpha before him and he’s pleased. Knows he’ll get strong pups from this alpha, knows this alpha will keep them safe.
Katsuki can feel slick sliding down his thigh from where Izuku sits, can see his little cock hard and straining. His own cock is aching, an angry red with the knot already a little inflated at the base. Izuku is toying with it, inspecting but also teasing him– Katsuki can tell by the devilish little smirk on his lips.
“You just gonna look at it all day, omega?” He challenges.
Izuku locks eyes with him, emerald green glancing up from under long, pretty lashes, but he doesn’t move.
“C’mon, omega. Take what you want,” he provokes him.
Izuku gives him that smile again and it’s equal parts chilling and arousing. Fuck. Something is a little off, though. Izuku’s eyes…he still seems feral, but there’s a dangerous sort of intelligence in them now. A sort of calculating.
“Take what I want,” Izuku repeats, gripping Katsuki’s cock so tight he can’t help but whine. “Fine.” He doesn’t waste another minute, scooting forward and lifting up so he can position Katsuki’s cock at his entrance before he let’s gravity take him all the way down. Bottoming out in seconds has Katsuki moaning loud enough to be thankful for the soundproofed room.
“Want your pups, alpha,” Izuku tells him, lifting up and dropping back down to start a breakneck pace. Fuck, the nerd’s thighs are ridiculous but Katsuki never realized just how much until now. “Gonna take and take and take until you give me what I want, Kacchan.”
A part of Katsuki, a tiny part somewhere in the far back of his brain with most of his higher reasoning ability, thinks he should be worried about that. The majority of him thinks the feeling of Izuku’s wet little hole sliding up and down his cock while the omega’s slick drips down his balls is the single best thing that’s ever happened in the universe. “Yeah,” he agrees mindlessly, “take it, baby, take whatever you fucking want–” he goes to move his hands to grip Izuku’s thighs without even thinking about it but the omega immediately freezes and snarls at him again.
“Stay, alpha,” he orders, clenching hard on Katsuki cock. The alpha is quick to put his arms back into position and waits with bated breath to see what Izuku will do. A few tense moments pass before the omega resumes riding him, reaching down to tug at his own little cock as he does. “Mmm, good alpha. Gonna give me your knot, gonna give me your pups,” he smiles, rubbing at his stomach as he thinks about it.
“Fuck yeah,” Katsuki agrees, using his hips to meet Izuku thrust for thrust, thankful for all their hours spent in the gym. “I’m gonna fill you up, pretty omega. Gonna knot that tight little hole and give you so much cum you’ll already look pupped. Bet you’d like that, huh? I’ll keep you on my cock nonstop, just you wait, baby,” he moans, and can already feel his knot catching. “You ready, baby? Ready for my knot?”
“Yeah, alpha,” Izuku whimpers, his own orgasm sneaking up on him. “Wanna come on your knot, alpha. Wanna come when I feel you filling me up. Want you to breed me full, alpha. C’mon, fill me up, Kacchan– oh, oh, oh!” His little omega cock spurts a thin clear fluid the second he feels Katsuki’s knot lock into place, whining as his walls flutter and milk Katsuki’s cock for all it’s worth. The alpha below him is groaning, hips stuttering in small little thrusts as he empties himself inside the omega. True to his word, Izuku’s little stomach swells up just a bit as Katsuki’s first orgasm crests and comes down.
A moment passes where they both just breathe, Katsuki’s cock still coming just a bit every few seconds. Izuku is still gently rubbing his own cock, his heat only allowing him satisfaction for a moment.
“Alpha,” he calls out and waits until Katsuki’s tired eyes open to look at him. “Take what I want?”
“Huh?” Katsuki replies, most of his brain cells still rebooting.
“Alpha said to take what I want.” Izuku reminds him with an innocent little smile that feels anything but.
“Izuku–”
Izuku doesn’t let him finish before tugging on Katsuki’s knot and then pressing back down. There’s absolutely no getting it out without hurting them both but the little omega has just enough room and leverage to pull up an inch or so before slamming back down– just enough room to send Katsuki into overstimulated hell.
“Fuuuuuck,” he groans, quickly moving his arms to try and hold Izuku still. The omega beats him to it, green lightning flashing around his scarred hands as he presses down on Katsuki’s wrists to hold the alpha in place. He keeps moving, keeps milking Katsuki for every drop, while the alpha whimpers and begs senselessly beneath him. He can somehow see that terrifying mix of awareness and ferality in Izuku’s eyes. Can tell the little nerd knows exactly what he’s doing but that he’s absolutely still on the edge. “‘Zuku, fuck, you gotta– shit, gotta stop, baby. You’re gonna fucking kill me, holy fuck.”
“No,” Izuku growls his answer, baring his canines again as he clenches hard on Katsuki knot. “I’m taking what I want, Kacchan,” he says, moving to lap dangerously at Katsuki’s throat. Katsuki is pretty sure Izuku won’t actually try to mark him but he was also pretty sure the nerd didn’t have a sadistic streak before he decided to try and kill him via his dick. “Strong, alpha. You can take it,” Izuku tells him, scraping his teeth against Katsuki’s scent gland.
And as much as it all hurts it also sends him over the edge into another orgasm, strings of curses falling from his lips as he cock, high on Izuku’s heat pheromones, pumps another full load into the little omega until his stomach is more visibly full. There’s a sweet, blissful moment of reprieve where everything is quiet and Izuku just laps soothingly at his scent gland and Katsuki thinks it’s over.
Until Izuku sits up and smiles at him again. “Good, alpha,” he praises, pressing a kiss to Katsuki’s lips. “Ready?”
“Ready for wha–” He shouts as Izuku clenches down on him again. “Fuck, ‘Zuku, don’t you dare–”
Izuku does dare. He dares many, many times. Aizawa tried to warn him. Katsuki almost thinks he should’ve listened but when Izuku finally falls asleep and Katsuki catches a glimpse of all of that cum leaking from his pink, swollen little hole…well, he can’t say he has any regrets.
Besides, he’ll just make the nerd pay during his next rut.