Sometimes, Steve thinks he'll never be warm again. Since he woke up in the future, a chill has settled in his bones, and he wonders if this is all some crazy dream as he freezes and drowns in the ocean. The psychiatrists tell him it's all in his head, and he accepts that. He knows his apartment is heated; he can hear the steam clanking in the pipes, smell it rising like it's still 1938 and Bucky's going to come through the door any minute with a grin and a fresh loaf of bread he charmed off old Mrs. Krakowski. But at night, he still shivers himself awake, even beneath the heavy blankets covering his bed.
He works up a sweat beating the heavy bag at Sal's Gym, but the warmth never lasts the walk home. The chill sets in for real when Director Fury shows up with pictures of the tesseract. He has dreams that night of being bathed in cold blue light and icy arctic water, and wakes up with his teeth chattering, like he's still sixteen and suffering from pneumonia. He remembers the soft animal heat of Bucky's body curled around him and shivers harder in his big empty bed. He gives up on sleep, instead spends the night reading the file Fury delivered, and he's ready and waiting when the black car arrives for him in the morning.
He thaws a little under Agent Romanoff's matter-of-factness and Dr. Banner's diffidence, and a little more after they all fight aliens together and win. His team is still alive and whole (if not unscathed). He feels comfortable enough to go for a meal with them afterwards, to let his guard down and close his eyes over his plate, trusting them to have his back if anything goes wrong. But then they go their separate ways, and the warmth of their camaraderie, of a battle well-fought and won, begins to dissipate. He starts out excited about his trip, but the succession of memorials and headstones chills him through, despite the summer sun shining down on him.
He comes back to work for SHIELD, lets himself sink into missions and training. When he's camped out somewhere in the Rockies with a small group of SHIELD agents, he tries not to think about sleeping in a tent in the Alps, him and Bucky in a sleeping bag barely big enough for one of them and pressed together so snugly they didn't even feel the cold.
He doesn't know if he'll ever find that with someone else. He doesn't even know if he wants to, but he knows he wants something more, and Peggy's no longer an option. He's thinking about actually taking Natasha up on her offer to set him up when he gets Bucky back. Everyone else calls him the Winter Soldier and is terrified, but Steve never doubts Bucky is in there, and he's vindicated when, after months of intensive deprogramming and therapy, Bucky looks at him and smiles.
Now, he and Bucky keep each other warm, like twin suns that only burn together.
In the steamy shower, Bucky presses him up against the cool, tiled wall and drives the chill away with fiery kisses, until Steve is dizzy and feverish with them, and Bucky licks sweat and hot water off his skin before he engulfs Steve in the heat of his mouth. Steve tangles his fingers in Bucky's hair and holds on, his face tipped up, eyes closed against the hot water sluicing down over them, and feels warm inside and out. Bucky teases him with fingers and tongue until he can't contain himself, and he comes with a low moan, spilling himself down Bucky's willing throat. Then he licks the taste of himself off Bucky's tongue and reaches down to cup the hard, hot length of his cock and stroke.
"Wait," Bucky murmurs against his jaw. "I want to come inside you."
Steve shivers at that, but not because he's cold.
They wrap themselves in towels and dry off quickly, because Steve doesn't want to wait, but he doesn't want to the sheets to be cold and damp afterwards, either. Bucky appreciates his pragmatism, but he doesn't make it easy; he wraps himself around Steve and peppers his neck and throat with quick little kisses and bites, and curls a hand around Steve's dick, which is getting hard again already.
"You keep that up, I'm not gonna make it to the bed," Steve mutters hoarsely.
Bucky laughs and bites him in the spot where his neck meets his shoulder. Steve huffs in mock annoyance, slings Bucky over his shoulder for the quick trip into the bedroom, and then dumps him on the bed. "Who's laughing now, tough guy?"
Bucky tugs Steve down beside him, and then rolls them over so he can press Steve back against the pillows, which are soft and warm against his back.
The lube is slick and cool at first, but it warms quickly as Bucky works him open. Steve loves it, the heat and the friction and the ache of being opened and then filled. He squirms and begs, planting his feet and thrusting his hips while Bucky fingers him, pleasure bursting under his skin like mortars.
"Please," he says, "Bucky, come on."
"Look at you," Bucky says, spreading Steve open even further and rubbing his thumb over his slick, aching hole. "Fucking gorgeous."
He slicks his cock and pushes in slowly; Steve feels every inch of him. Bucky thrusts hard, his hands tight and steady on Steve's thighs, his belly brushing much too lightly against the underside of Steve's rock hard cock as he leans into bite at Steve's lower lip. Steve hangs onto him, still begging wordlessly for more as they move, his whole body flushed with heat and need.
Bucky's fingers dig into Steve's thighs, and his hips stutter as he comes with a low moan that vibrates through Steve as he licks it off Bucky's tongue. Steve reaches down and strokes himself to completion, his orgasm roaring through him like a forest fire.
He clings to Bucky when they're done, sleepy and satisfied, and warm all the way down to his bones.