Chapter Text
The cold lighting of the Avengers’ infirmary was almost stifling. The hum of monitoring machines and the faint buzzing of holographic screens were the only sounds filling the air, aside from Sif’s heavy sighs. Lying on the cot, she felt exhausted, weak, feverish.
She had sent all the humans away. She only wanted Loki. If she was going to find out what was wrong now, she didn’t want to be vulnerable in front of the others. Not even Thor.
Tony Stark, with his usual brazen genius attitude, turned toward her, raising an eyebrow as he scrolled through the information projected in front of him.
Loki shot him a sharp glance. “And since when are you a doctor?”
“There was a time when palladium was slowly poisoning my blood, and another when I realized that coming home to my partner with open wounds wasn’t exactly the best way to keep romance alive in a relationship. So, I started studying.”
“Where’s Bruce?” Sif asked. “I’d like him to be here as well.”
“I believe—and hope—he’s currently playing doctor with Widow. Don’t worry, Lady Sif, this is just to give us a general idea of the situation. I’ve activated my medical A.I. to run a scan. Bruce is a biologist—he can examine the results once we’re done here.”
Sif nodded.
“Okay, Lady Sif, let’s start with the basics. How far along are you? Oh, wait—I have no idea how long an Asgardian pregnancy lasts, considering your lifespan. 200 years?”
Sif shot him a tired, almost irritated look. “It lasts just a little longer than a human pregnancy. About ten months. And I also know exactly when it was conceived. Twenty-two weeks ago.”
Tony nodded with a smirk. “Oh, how romantic. So, it was one of those unforgettable nights, huh? Your hubby must have really done a number on you.”
Sif scoffed, while Loki, who had been silently standing beside her until then, crossed his arms and fixed Stark with his signature icy glare. “I suggest you say nothing more, Stark.”
Tony raised his hands in surrender. “Hey, just for scientific accuracy. Alright, so let’s talk timing… At twenty-two weeks, the baby should already be visible and fully formed. At least in a normal pregnancy. Let’s see what we’ve got here.”
He turned toward the console and typed in a few commands. A thin beam of light passed over Sif’s skin as the advanced ultrasound scanner analyzed her abdomen. Within moments, a three-dimensional image began to take shape on the screens in front of them.
“There we go—ultra-HD deluxe vision of Asgard’s little prince. Stark service, only the best.”
And there, suspended in a bluish glow, was him.
The round little head, with a delicate profile already taking shape: a barely defined nose, thin, closed lips, and tiny eyelids hiding eyes that were still sealed. His arms and legs moved in small, jerky motions, while his incredibly well-defined fingers opened and closed in instinctive movements. And then, the heart— that tiny, pulsing point that seemed to echo through the entire room.
Sif held her breath as she basked in that rhythmic, rapid sound.
“He’s… so small.” Her voice was barely a whisper.
Loki, who had remained still until then, took a step forward. His usually impenetrable gaze had softened. Without a word, he knelt beside her, his face illuminated by the soft glow of the hologram.
“I never imagined I’d see something like this. He has your profile.”
Sif took his hand and squeezed it tightly.
“It’s a boy, isn’t it?”
Tony checked the monitor.
“Unless that’s a tail in reverse, I’d say yes.”
“Just as my mother said.” He wished Frigga were there with him at that moment.
“Hey, prince, you’re not about to start crying, are you? I don’t think I can handle that.”
“Yes, Stark, I’m having an emotional moment. Can you do me the honor of not ruining it for at least thirty seconds?”
Sif turned to Loki with a weak smile, while he gazed down at her with an intensity that sent shivers down her spine. He gently brushed her cheek, his thumb tracing a soft circle over her skin.
Then Sif noticed the dark expression on Tony’s face.
“What is it?”
He stared at her for a moment before turning back to the monitor, his tone suddenly dropping.
“These readings… they’re not good at all. The baby’s genetics don’t match the Asgardian profile I have. Their temperature is slightly higher than the mother’s—normally around 37.5 to 38°C—because they’re submerged in amniotic fluid and get heat directly from the mother’s body. But his temperature is 25 degrees. Honestly, with these vitals, he should be dead.”
Sif hesitated, looking at Loki.
Tony didn’t miss the exchange between them.
“You don’t look surprised. Is there something I should know?”
Loki met his gaze.
“The child is not fully Asgardian.”
Sif squeezed his hand, as if offering him courage.
“I am a Jotun, a Frost Giant. I was adopted by Odin as an infant.”
“Hold up, hold up, hold up. Wait a second. You’re telling me you’re not just an annoying demigod with a superiority complex, but also an interdimensional… Popsicle? A giant one at that? If you’re what you call a ‘giant,’ you guys have a very interesting concept of size.”
“It was a recent discovery for all of us,” Sif interjected, as if she had been stung.
“My parents did a very good job of hiding my origins. It was only by chance that I found out.”
Tony scoffed. “Yeah, yeah, very touching and all, but let’s get back to the point. Sif, we’ll need to run more tests to understand what’s happening to your body. And Loki, I need your blood.”
Loki tensed. “For what reason?”
“Because I need to know what damn physiology I’m dealing with. It’s not every day you get to analyze a half-Asgardian, half… well, whatever the hell you are.”
Loki gritted his teeth but eventually extended his arm. “Not whatever. I am a Frost Giant.”
Tony raised an eyebrow as he drew a sample, pricking him with a needle.
“Ow.”
“Interesting, Frozen. Care to enlighten me on possible complications? Is there anything we should know before proceeding with the tests? Like, I don’t know—how long does a pregnancy last for, uh… Frost Giants?”
“How the hell should I know, Stark? It’s not like I’ve ever had the pleasure of sitting down for tea with my kind to discuss their reproductive habits.”
“You’re not very useful, you know that?”
Loki scoffed.
“I don’t know, alright? I never wanted to know. I studied their magic, nothing more.” He hesitated for a moment. “I never thought I’d need to understand the blood of those who abandoned me.”
“We fought the Jotuns before Thor’s exile,” Sif noted. “They told us many stories about them when we were children.”
“Yes. They were the monsters parents spoke of at night.”
Sif cut him off before his thoughts could take a darker turn. “They live in frozen wastelands, they can withstand glacial temperatures. They can generate and manipulate ice at will. Some of them can freeze objects or living beings with just a touch.”
Tony nodded.
“That could interfere with Sif’s thermoregulation. If the pregnancy is altering her body temperature or her resistance to cold, it could be causing physical stress… high fever, fainting, exhaustion.”
Tony scanned the blood sample, and within minutes, the results appeared on the monitors. He rubbed his chin, nodding.
“Yeah, I think my theory holds up. Her body is trying to adapt to the baby, but the biological difference is putting her under strain. If her temperature keeps rising, she could face serious complications.”
Loki turned to Sif, his face tense with worry. “What can we do?”
Tony sighed. “We need to find a way to stabilize her body temperature without compromising the baby’s growth. It might be necessary to create a controlled thermal environment around her or develop a specific treatment. But we’ll need to run more tests.”
Sif closed her eyes for a moment. She felt exhausted, but the warmth of Loki’s hand on hers made her feel stronger.
“We’ll get through this,” he whispered, just for her to hear. “No matter what, I will protect you and our child.”
She turned to him, a soft smile on her lips. “I know.”
Tony scoffed. “Alright, enough with the romantic movie moment. For now, I’ll start you on an IV to keep you hydrated, Lady Sif, and monitor your temperature. Meanwhile, I’ll run a cross-analysis of Loki’s and your genetic makeup to find a way for both to work together safely. If the baby’s physiology is more… Jotun than Asgardian, we might need to adjust something.”
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The air in the room was tense despite the silence. Thor sat on one of the reinforced chairs, arms crossed over his chest, his gaze fixed on Loki, who, on the other hand, seemed incapable of keeping still. The God of Mischief paced back and forth, hands clasped behind his back, his face marked by a tension that, despite his efforts, he couldn’t hide.
Tony had asked to speak without Sif present. Loki had left her asleep, and after a quick wash and changing into comfortable clothes—ones that were completely devoid of his usual regality—he had set off with his brother to meet the two scientists.
Thor sighed, shaking his head. “Loki, if you keep that up, you’re going to wear a hole into the floor.”
Loki stopped abruptly and shot him a glare. “And what exactly am I supposed to do? Smile and wait patiently while I let a group of mortals decide the fate of my wife and child?”
“These mortals,” Thor emphasized patiently, “are currently our only solution. Stark can be irritating, like a thorn in one’s side, but he has proven his intelligence many times. If anyone can figure out what’s happening, it’s him. And Banner is an excellent scientist.”
Loki scoffed, turning his face away. “I don’t trust them.”
Thor observed him for a long moment, then stood up and approached him, placing a hand on his shoulder. Loki tensed for an instant but didn’t pull away.
“I know this isn’t easy for you,” Thor said sincerely. “I know relying on others costs you more than you’d ever admit. But you have to believe me when I say Sif is in good hands.”
Loki lowered his gaze, his jaw tight. “And if they’re wrong?”
Thor shook his head. “Then we’ll make them fix it. But you are not alone in this. I am here, brother. For you, too.”
Loki slowly lifted his gaze to him, an emotion flickering in his eyes that was difficult to decipher.
“Do you truly care?” he asked quietly.
Thor gave his shoulder a small squeeze. “Sif is my best friend, Loki. And the child she carries is my nephew. I won’t let anything happen to them.”
Loki looked away, taking a deep breath. He didn’t reply immediately, but Thor didn’t need words to know his message had been received.
After a long pause, Loki simply said, in a calmer tone, “If Stark says anything inappropriate, I’ll freeze him.”
Thor chuckled, giving him a pat on the shoulder. “That would actually be quite amusing to watch. But try to hold back—at least until he finds a solution.”
Loki gave a small, almost imperceptible smile, but it was there. And for Thor, in that moment, it was enough.
Tony entered the room with Bruce, scrolling through the latest data on his tablet. “Alright, I’ve got good news and bad news.”
Loki lifted his head, his expression guarded. “The bad news first.”
Bruce removed his glasses and rubbed his temples, staring at the monitor with an expression that was equal parts fascinated and concerned. Tony stood with his arms crossed, tapping his fingers against the table.
“Your turn, Dr. Banner,” Tony said.
Bruce sighed and pointed at the genetic analysis of Loki displayed on the screen. A series of DNA sequences intertwined in complex patterns, with several red-highlighted areas flashing like anomalies.
“Okay, let’s put it this way: if human DNA is a book written in a specific language, Loki’s DNA is… an ancient manuscript written in two different languages, with a third language that someone attempted to translate halfway through.”
Thor huffed. “Yes, thank you, very clear. And in words for normal people?”
Bruce pointed at two distinct sections of the genetic code. “This part here is clearly his Jotun heritage. Structurally, it’s very different from Asgardian or human DNA—these sequences are optimized for survival in extremely cold environments.
There’s a component linked to thermal regulation, likely what allows Frost Giants to survive in temperatures that would kill any other living being.”
Tony whistled. “Interesting. And the part that looks like an alien footnote?”
Bruce frowned. “That’s the part that concerns me. It’s as if someone took his original DNA and… reorganized it. Not just altered it through natural mutation. It looks like his Jotun genetics were rewritten to blend in with Asgardian physiology.”
Tony raised an eyebrow. “Wait, you’re saying he wasn’t just adopted by the Asgardians, but they also reprogrammed him at a genetic level?”
“Odin was one of the most powerful and ancient beings, and our mother was raised by witches. They managed to hide a truth that we all deserved to know, not just my brother,” Thor said darkly.
Bruce nodded. “It’s not just a matter of appearance—the magic rewrote his entire genetic makeup to make him look and function like an Asgardian. But the strangest part is that the two halves—Jotun and Asgardian—didn’t simply merge. It’s as if the Jotun DNA was put on ‘pause.’ Almost deactivated, I’d say.”
Tony folded his arms. “So inside him, the gene is switched off, but the baby has it in full on mode. Or at least, dangerously close to fully activating.”
Bruce bit his lower lip. “In theory, Loki could revert to being a full Frost Giant if he didn’t have the ability to suppress the gene. At least genetically, with all the consequences that entails. And it looks like the baby is developing more Jotun traits than Asgardian ones.”
Tony slowly turned toward Loki, who had been listening in silence. His green eyes were fixed on the monitor, his face unreadable, but his hands were clenched into tight fists at his sides.
“…Loki?” Tony prompted.
Loki lowered his gaze to his hands, as if expecting to see his skin change color before his eyes.
“So… the child I’m expecting with Sif is basically a little Jotun time bomb that could, at any moment, explode and freeze Sif from the inside out?”
Bruce nodded slowly. “I think so. We’ll need to monitor her constantly.”
Silence fell over the room. Then Tony sighed and ran a hand through his hair.
“Great. Problem number one hundred on the list. Do you have any idea how this part of you works? Can you control it?”
Loki hesitated. He had never spoken about this subject with anyone—especially not with his brother, after everything that had happened.
“I didn’t know I was different until they told me. And even after I found out, my body didn’t react immediately… as if the magic surrounding me was stronger than the truth I had been told. Gaining control wasn’t immediate. It took years of attempts, of frustration… and patience. It’s a balance between two natures that should cancel each other out. I learned to shift the weight from one side to the other, to choose which part of me to let surface. But it’s not perfect. It never has been. When I take Jotun form, I’m not like them. My body remains… mitigated, I’d say. I don’t emit the same lethal cold, I don’t freeze people on contact. I’m not one of them. Not completely.”
He paused. Thor placed a hand on his shoulder while he kept staring at the monitor, the blue glow of his DNA’s double helix reflecting in his eyes.
“You also mentioned good news?” Thor asked, breaking the silence.
“The balance between your genetics and Sif’s is more complicated than we expected, but for now, the baby is genetically stable. We’ve identified the core of the problem: Sif’s body recognizes him as a foreign presence and is trying to adapt, which is causing her temperature to rise.”
Loki clenched his jaw. “And what exactly is the good part of this news?”
Tony crossed his arms. “I can slow down the process. If we keep her body temperature around 34°C, she might be able to sustain the pregnancy longer with fewer side effects.”
Bruce suddenly lit up as if struck by lightning.
“I have an idea. It could be highly invasive… but I think it could solve the problem permanently.”
“Speak.”