The Beautiful and the Damned

It starts off innocently enough.

Loki's back on Midgard because Odin wants him under Thor's protection, and Thor feels like Midgard is more his home now, so he'd prefer to watch over Loki here. And then Thor makes Loki stay at the Avengers Tower—formerly Stark Tower—because he's there more often than not and it would be easier for him than having to go check on Loki at an apartment.

(Besides, there's the unspoken theory of Thor's that any building inhabited solely by Loki would end up demolished and halfway to hell in five seconds flat.)

The first time Loki goes to Tony's room for sex, it's late at night and everyone else has already gone to bed, except for Steve, who likes to swim laps in the underground pool after midnight. Tony's coming out of the bathroom in a black ribbed V-neck and boxers and is so startled to see Loki lounging on his bed like it's normal that he almost drops his glass, which is half full with some very aged, expensive liquor.

"Jesus fuck," Tony says after a few seconds, his hand over the arc reactor, a faint blue glow peeking out from between his fingers. "Knock before you come in my room, okay?"

Loki does not say anything, his eyes traveling up and down Tony's body. He's wearing a green button-down and tight black pants which leave little to the imagination, and after a few seconds he swings his legs over the side of the mattress and stands up, walking across the room.

This is how I die, Tony thinks, and says, "You know, I hardly think now is an appropriate time to be trying to kill me, Laufeyson."

Loki takes the drink from his hand and tilts it back to his lips, letting the liquid slide down his long, pale throat before setting the glass aside and hooking his arms around Tony's neck. "Don't flatter yourself, Stark," is all he says, and when they kiss, it's nothing like in the books. It's brutal and hard and cutting, and Tony, who recently visited one of New York's finer strip clubs, can say with definitive certainty that he has not ever kissed better than this. Loki's skin is cool on his, and that first night, even though Loki tops, in the end it's Tony who feels like he's doing the protecting.

In the morning, the god is gone, and Tony puts it down to his half-drunken state and Loki's boredom and forgets about it.

But there's a second time, and then a third, and by the fifteenth time it's not innocent anymore, and Tony's wondering if there's something behind these late-night visits. He kind of wants to ask Thor about it because Loki's technically Thor's brother and he of all people would know where Loki's stance on relationships is, but he's not really ready to tell the blond god that he's been fucking his brother for the past three months without letting anyone know, not even Pepper—and besides, Loki should be leaving any day now, right? Going back to Asgard to sort things out with Odin?

He asks Loki this on the nineteenth night, after sex, when Loki is lying half on top of him, wearing his Black Sabbath t-shirt and nothing else, his long fingers splayed over Tony's arc reactor (and Tony's wondering why he ever thought Loki would rip it out because honestly the only thing Loki's ever done near it is bite the skin, and there's nothing to complain about there). The god looks at him for a few seconds, and his expression is unreadable when he sits up.

"Do you wish me to go now, Stark?" Because he's still Stark, somehow, after three months, and even though it sounds great spilling out of that throat when it's being screamed, it sounds accusatory in regular conversation, and Tony doesn't like to be accused, it makes him feel trapped.

"Lights, JARVIS," he calls, and the lights come on, a little dimmer than normal.

Tony fixes his eyes onto Loki's and, of their own accord, his hands come up and cup Loki's jaw. "I am just asking," he says, "because you showed up in my room three months ago and fucked me without explaining what you were doing, and now we're still in that same position, and it's great, but I'd like to know at some point whether I should go about telling people."

Loki frowns a little. He's tense under Tony's hands, but he doesn't move. "Why would you tell anyone?" he asks. "I assumed this was not a big deal for you; that is why I make sure to leave in the mornings and only come once or twice a week, if that often."

"You still haven't answered my question, hon," says Tony, and Loki ignores the way his chest tightens at the term. "Why'd you come here in the first place?"

"Maybe I like the way your mind works," Loki replies, proud of how even his voice is, even though Tony's thumb is on his throat and he's pretty sure he can feel how much he's shaking right now. "You always struck me as the most brilliant of your pack of 'lost creatures', Stark. Physics, math, science, inventions…"

"They don't call me a genius for nothing," Tony shrugs. His eyes sweep down to where their legs are twined around each other—and how the hell did that happen, because the last time Loki checked he was sitting straight up and Tony was still lying down—and he chuckles, and the smile that crosses his features is small but genuine. "But I think if you were only interested in my mind, you would've just broken into my lab and pissed me off by taking my stuff."

"Things can change," is all Loki will say, and curses himself when he feels a blush beginning to spread over his cheeks. To compensate for being weak, he reaches down and trails his fingers down the sides of the arc reactor, and smirks when he feels Tony shiver beneath his touch. He leans in and their lips meet, slow, even, smooth, heat on cold. Tony moves his hands from Loki's jaw and down to the hemline of his shirt, and Loki lets out a soft sigh into the mortal's mouth at the touch on his sharp hipbones. Three months after that first time, it's no wonder they know how to touch each other. Tony flips him onto his back, and his legs hook around Tony's waist, and their twentieth time, same night as the nineteenth, moves in with the sunrise.

In the later part of the morning, Loki wakes up stiff and sore, still underneath Tony, who is curled around him, a tiny smile on his lips. He shifts and the movement wakes Tony, and the first thing he notices is that he's slept with an Aesir god, and the second is that said god looks genuinely pleased with himself.

"Good morning," says Tony cautiously. "Decided to stay the night after all?"

"I told you. Things change." Loki's still smiling when he leans in and kisses Tony, and it's slow and almost passionate and familiar and warm, and it makes the billionaire smile too, because he really has to thank Thor at some point for bringing his adoptive brother here.

Then Loki's swinging his legs over the side of the bed, flashing a grin over his shoulder as he stands up. "Join me for a shower, Tony?" he asks, and Tony barely has time to register the use of his first name before he's practically throwing himself at the god, and both of them are laughing as they stumble into the bathroom.

Not innocent. Not anymore.

(Tony wonders for years afterwards how it ever came to this, and finds, as he cards his fingers through Loki's hair and allows him to change the channels on his widescreen television, that he doesn't really care.)