A/N: Written for a prompt on avengerkink. Also, there's obvious mentions of Thor/Loki which is incest? pseudo-incest? Warning in case that's a trigger for anyone. Shameless crack with a sad attempt at real plot ensues.
"Huh," Bruce says.
Tony looks up from the metal he's tinkering with and sees Bruce standing in front of four separate computer screens, squiggles of DNA floating in front of him. There's no table for Bruce to tap his fingers on so he's tapping them on his leg, and apparently he has no idea he's talking out loud.
"Huh," he says again and grabs the nearest writing utensil and clean sheet of paper he can.
Tony waits for Bruce to finish jotting things down, because as much as he wants to tease Bruce, he doesn't want to distract him from whatever discovery he's just made.
"You just going to stand there and talk to yourself or are you going to share with the class?" Tony grins when Bruce turns to him, but there's no adorable embarrassed flush across his face, no awkward stuttering. Bruce is so into whatever he's just discovered that Tony's teasing has no effect, and Tony thinks that might be the hottest thing he's ever seen.
"I need Steve," Bruce says, cutting short Tony's fantasy of pinning Bruce to the nearest wall and kissing him senseless.
Jealously curls in Tony's stomach. "You need Steve for science?" Tony knows his tone is derisive, and he'll feel bad about it later, but not right now, because all he wants is Bruce, and he doesn't care what he has to say or how he says it in order to get him.
"I need to stick things in him," Bruce says, in total science mode. Meaning, he completely misses the way Tony's hands curl into fists, and he rushes out of the room without a second glance.
When Tony next sees Bruce, he's with Steve, but not the way Tony had first imagined. Steve is hooked up to all sorts of machines, and it's needles that Bruce has stuck him with, and Tony can relax. A little. It helps when Bruce starts pacing and muttering to himself and then he pushes his glasses up his nose and they slide back down, and Tony forgets all about Steve and science and all he wants to do is kiss Bruce again.
"This is fascinating," Bruce says, scanning the data that's being pulled up. "Your genes have changed. Did you know that?"
Steve hasn't learned yet that most questions asked in a science lab are rhetorical. "The serum was supposed to do that, right?" He looks vaguely concerned that his body has been changing on him, and all the foreign machinery around him isn't helping.
"No, look at this," Bruce says, pointing to screens full of information that means absolutely nothing to Steve. "They changed with the serum, of course, but they changed again after you were frozen. Something inside of you responded to you being in the ice. I wonder if that's how you survived. I wonder what it is."
Bruce peers at the numbers in front of him as if they have all the answers. "Wait. Wait!"
Steve wants to say that he's not going anywhere, but he's a little afraid of this side of Dr. Banner so he remains very still and hopes that's good enough.
Bruce pulls up several other screens. He knows that sequence. He's seen it before. It's not a common one so he runs it against all non-human entities they've run into. He taps his fingers on his lips as he waits, his mind racing his computer to see who figures out the pattern first.
The computer flashes Thor's face at him, and Bruce drops his pencil. "We need to see Fury."
Clint is pissy because they've been called into a meeting on their off day that doesn't even have anything to do with super villains, and his mood doesn't improve once Bruce starts setting up charts and comparisons that no one in the room can understand except for him. Not even Tony understands the intricacies of advanced genetics which gives Clint a little comfort but not much.
"Dr. Banner," Fury interrupts mid-tirade. "You can skip the explanation. What is your point?"
Bruce pulls up a close-up of Steve's DNA and another of Thor's. The room might not understand DNA, but they can see patterns and Natasha is the first to speak, a soft Russian curse.
"Oh shit," Tony echoes, staring at the screens before turning to Steve.
Steve has an adorable confused smile on his face that makes his whole face scrunch up. "I see it, but what does it mean?"
"You're part Asgardian," Bruce says, no sugar coating, no preamble, because he's good with facts, not feelings.
Steve's mouth drops. He's what? No, he's a kid from Brooklyn who got beat up a lot and then became a super soldier. Only, Bruce apparently have evidence, and Steve doesn't trust science, he doesn't trust what he can't see or feel and destroy, but he trusts Bruce. This is just too much to handle.
"So my mom got visited by a god?" Steve asks finally asks, voice quiet.
"Not quite," Bruce says. He pulls up another picture. "I don't know what else makes up your DNA. It's like nothing we've come into contact with. It's the strangest thing. After the serum your human DNA melted away, but the scientists who've been studying with you couldn't pick it up."
"The serum made me an alien?"
Tony rolls his eyes. Honestly, he needed to make a genius superhero club. "No, your parents made you an alien."
Steve bristles at Tony's tone, but he brushes it off, because there are more important things to deal with. His parents didn't make him an alien. His parents were two wonderful people that loved him and raised him and were killed in a bread riot. People didn't adopt during the Great Depression, they were too busy trying to keep themselves alive. This was a lie. Science was like magic; it didn't make any sense and it was full of lies which actually made it kind of like Loki now that he thought about it, but really none of that's important. The only important thing is that Steve knows who his parents are, and none of them are gods.
Steve can feel everyone staring at him, and that's not helping him to calm down. He's not a freak, he's not an alien, and he certainly wasn't adopted. He surges to his feet and upturns the desk he's sitting at, and everyone in the room jumps away from him.
"I'm not adopted!" he shouts and the desk slams into the floor, punctuating his words. He spins to Tony, to Bruce, not sure which one he wants to attack first.
"Stop," Thor commands. "I have a question."
Miraculously, Steve listens. He doesn't pick up the desk and throw it through a wall, and he doesn't launch himself at Tony. Fury still puts a response team on stand-by. Just in case.
"Why did my picture come up?"
"You're the only Asgardian we've tested," Bruce says. "Though," he pauses and flits his eyes around the room, unsure if he should continue.
"What is it, Dr. Banner?" Fury asks, endlessly patient and calm as if he wasn't just informed that Captain America was technically an illegal alien in the truest form of the phrase.
"I don't fully understand Asgardian genetics," Bruce says. He looks at Thor and then at Steve and quickly looks back at Fury before he can lose his courage. "There's evidence that Steve and Thor might have a connection deeper than being of the same race."
Bruce tries to obfuscate his meaning, but everyone in the room gets it. Steve looks like he's about to destroy the room or start crying. Clint looks like he's about to be sick, and Natasha is looking curious. Tony is trying to decide whether or not he's going to risk making a Star Wars joke or not.
And Thor is crossing the room so he can stare at Bruce's findings. Bruce jumps back at first, afraid he's about to get decked for something probably having to do with sullying honor, but Thor just starts pointing to the progression of Steve's DNA from when it was first taken by Dr. Erskine until Bruce's most recent testing.
"Explain," Thor orders.
Bruce's hands flutter at his sides. "Uh, what part exactly?"
Thor points to each test done. "His DNA shifts, yes? Why? What does it shift to? What prompts it? I want to know everything."
"Interesting way to deal with finding out that you're a dad," Tony says. Fury shoots him a look that says 'shut your mouth or I will let Steve kill you'.
Bruce shrugs and starts trying to figure out how to explain DNA mutations to a Norse god. "Well, this is him pre-serum. The Asgardian DNA starts to become more prevalent after the serum. This second set of DNA, the unknown seems to have been triggered by the ice."
Bruce doesn't get any further in his explanation, because Thor picks up the nearest chair and throws it against the wall. Fury and Coulson have to duck, and they're wondering if their guns will have any effect on a god that seems to have gone crazy when Thor sinks to his knees and bellows. It's part fury part sadness, and Thor starts beating his fists against his chest as tears stream down his face.
The whole room shakes, and no one knows what to do because Thor is going crazy on one side of the room, and Steve is sitting on the floor, rocking himself on the other side, and that's when Loki decides to show up.
He appears in the middle of the room, his cloak billowing around him, and Fury closes his eyes and hopes they make it through this alive.
"You haven't pitched a fit like this since I engraved my name in Mjolnir," Loki says, smirking as he makes his way over to Thor. "I can hear you all the way from Asgard, you know."
Thor pauses when he hears his brother's voice. "Can you?" His voice is lower now, but raspy from the screaming. "You can hear? Good." Thor leaps to his feet, shaking his fist at the ceiling. "Here me, Odin, for you do not deserve the title of Allfather. I will have my vengeance for your deceit."
Loki's eyebrows raise, a delicate expression in comparison to Thor's magnificent display of temper. "What's daddy done now? Did he tell you play time's over? Do you have to return to Asgard?"
Thor doesn't give in to Loki's goading like Loki expects him to. Instead Thor clasps Loki's shoulders, strangely serious. "Now is not the time for this. I have made a most," Thor struggles for the right adjective.
"He's a proud papa," Tony supplies cheerfully.
Loki slaps Thor's hands away, betrayal written across every line in his face. "You've created life?"
He looks so hurt, so broken, that Thor wishes he had Mjolnir so he could chuck it at Tony's head. Thor reaches his hand out to Loki. "Only once."
Confusion keeps Loki from raining hellfire down on SHIELD headquarters. "I do not understand."
Thor takes advantage of Loki's confusion to embrace him again. "Odin must have lied. Come, you understand human science, yes?"
Loki rolls his eyes. "Child's play."
Thor leads him over to the DNA displays, and Loki goes very still under Thor's arm. He looks at the sequences three times, just to be sure, before he slowly turns around. Steve has tucked himself into the corner of the room, watching the proceedings from between his fingers.
"He lives," Loki breathes. "I understand why you're angry with Odin."
"Okay, time-out for the mortals in the room," Tony says since no one else appears to have the balls to talk. "What the hell is going on?"
"Oh," Bruce says, his eyes going wide. He looks at Loki and then looks over at Steve and his eyebrows shoot straight into his hairline. "Oh my."
Loki's lips curve into a smile and he pats Bruce on the head like one would a puppy. "Not all mortals are stupid."
"Dr. Banner?" Fury asks.
"I know how Steve survived the ice," Bruce says, "and it has nothing to do with the super serum." There's a long pause as everyone waits for the answer. Bruce flicks his eyes over at Steve, afraid of how he's going to react. "He's half frost giant."
Fury is about to call Dr. Banner out for such a load of BS, but then he notices that Thor and Loki are holding hands, and they whispering to each other and occasionally looking over at Steve, and Fury feels a massive headache coming on.
"Does this mean I can't kill him?" Clint asks, an arrow trained on Loki's head.
Loki laughs. "As if you could."
"No," Steve says, quietly at first. "No. No. I'm-no! I'm not adopted!"
Pain flashes across Loki's face, and he teleports to the other side of the room, gathering Steve up in his arms. "It is a difficult burden," he says, pinning Steve's arms to his sides when he tries to struggle. "I know. I understand. If we had known you were alive, we never would've let this happen. We're not ashamed of you. We would've proudly raised you as our own."
"This is real?" Natasha asks as Steve crumples in Loki's arms. "This cannot be real."
"Loki and I had a child," Thor says. "Odin disapproved and after the child died during birth, he forbid us from continuing our relationship. He lied about the baby dying. Why would he do that?"
"Uh, didn't you two think you were brothers then?" Tony asks. "I'd say that's a pretty good reason."
"He did not fancy a child of Asgardian and Jotun genes," Loki says, rubbing Steve's back. "Perhaps he thought the child would be more monstrous than the others I've had. He was wrong. You're beautiful."
Loki cups Steve's cheek and kisses his forehead, and it's so unlike anything they'd ever expect, no one can do anything but stare. Loki, who had tried to destroy the Earth, was now soothing Steve. Fury would think this was another trick, except Thor is watching them with pride in his eyes, and Thor wouldn't comply with Loki's mischief. Not on something like this.
Tony laughs, breaking the moment and everyone turns to glare at him. He shrugs. "Sorry, I just realized that Steve's now related to an 8-legged horse."
Steve stiffens in Loki's arms and tries to pull away. "This isn't real. This," his voice falters. "This can't be real."
Loki sighs and steps back, though he's still holding Steve's hand. Steve watches as his fingers start to grow longer, turn blue, and he tries to jerk his hand back as the blue crawl up his arm, but Loki's grip is stronger than he expected.
Steve shakes his head. "Magic. This is a trick."
"Then how did you survive the ice?" Loki asks, his voice soft like he's trying not to scare a small animal. "Why can you lift Mjolnir when no one else can?"
"But I'm Captain America," Steve says, his voice breaking.
"Why should this change anything?"
Steve rips his hand free and roars. His skin ripples and changes and suddenly he's towering over the room, and blue, and Loki is looking at him, eyes shining with joy and sadness, and Steve only wants to rip his head off.
"Do you see me?" Steve demands, motioning to the frost giant form he didn't even know he could change into. "America doesn't want to be protected by a blue alien!"
"Who you are is not determined by what you are," Loki says, morphing into his Jotun form so he can look Steve in the eye. "You are the First Avenger, you are a protector of the Earth, and you are my son. What does it matter that sometimes you turn blue?"
"Funny coming from you," Steve says, and his sneer almost makes him sound like Tony. "Didn't you try to kill Thor when you found out you were a frost giant?"
Loki grabs Steve's arms, his fingers digging into the cold flesh. "I don't want you to repeat my mistakes."
Steve rips his arms free. "I don't want anything to do with you!"
"Enough!" Thor commands and the two turn to him, looking chastised. "We have been reunited and that is a cause for celebration, not for fighting. We will go someplace with more privacy to speak with one another. We have many years to catch up on."
Loki nods and Thor stares down Steve until he gets a weak nod from him as well. Thor grins, happy, and reaches his hands out to them. Loki holds one of Steve's hands, and they revert back to human form before Loki leads him over to Thor. Once they're all holding hands, Loki teleports them away.
"Well," Bruce says after a long pause. "Huh."
"This makes your crush on Captain America exponentially more messed up," Tony tells Coulson, a large grin on his face. Coulson looks a little green in the face and Tony laughs.