Set sometime after Captain America 2: The Winter Soldier. (It's an old fic I'm just now uploading.)
He doesn't know what it is at first. He's still getting used being Bucky again, getting used to having memories, a past, of being something more than a weapon. He's walking through one of the large everything stores he'd never seen before the war, and passes by the sporting goods. He's not even sure what the thing is, but it's small and it's blue and shaped perfectly to fit over the teeth.
It hits him though. It grabs him and doesn't let go. He sees the blue thing and he can feel the mouthguard between his teeth, keeping him from biting through his tongue or cracking his teeth. He's back in the chair with metal pads on his face and chest and so much electricity running through his body. His chest constricts and something tightened in his throat and the world becomes fuzzy like it has so many times before.
He's frozen in place, gaze locked on the piece of sporting equipment as the memory of the pain hits him harder than the realization it had been Steve he'd been fighting.
Someone bumps into him, knocking him out of the memory. He's reacting though, mechanism whirling and clicking to move his arm before he catches himself.
The woman doesn't even realize his hand's moved to the knife as she reached out to pull one off the hook with a polite, "excuse me," that he doesn't really hear.
His mind's still spinning and the lanky kid standing next to her's as skinny as Steve. For a second he stares, then he leaves. He turns and leaves with his heart pounding in his head and seventy years keeping him from blinking enough to clear it.
He's not exactly aware of walking through the store, or of even having dropped the plastic Captain America shield he had picked up from the toy department even earlier. His body is walking on its own accord as passes by shelves full of something. The doors to the frozen food section go unnoticed.
Bucky stops though, frozen in his tracks by the tactile sensation of icy air and the sight of the cloudy window in the black door. He's falling, snow swirling in the wind around him as the train and Steve speed away. He's shoved into a metal box with walls that are made of frost. They tell him the cryogenic chamber will freeze him quickly, but it's never quick enough to keep him from feeling it, from remembering it as strongly as he does now.
He can't breathe because the air hits his lungs and it burns. He's awake long enough to feel his body freeze in layers as it comes in contact with the cold.
Once again though, he's shoved out of the moment of suspended limbo. The door closes behind him and someone else walks through the door in front of him wearing employee clothes and nametag.
Bucky doesn't focus on that though. He sees the glowing red letters of an exit sign as the black door swings shut then open then shut. The Winter Soldier was trained to find the exits, to leave once the mission was complete. He doesn't even think when he sees the word. He just heads towards it.
His hands press against the bar, a loud clang as the metal one connects, then the door opens and Bucky steps out into the warm night. The humidity lies like a blanket over him, pressing down the heat of a world that is not measured in tens of degrees Kelvin. He tries to blink away the phantom sensations as sweat forms all over his body, sticks his clothes and hair to him. Bucky doesn't mind it though. It's something to focus on as the light of the street lamps on the deserted street want to pull him to some other time.
He walks for hours, until he shakes the tightness in his chest and the tensed muscles and the feeling that Bucky Barnes is disappearing again and that he is still the Winter Soldier. He walks until the holes in his memory return to being holes that he's not certain he wants to be filled.
When he ends up back at the healthcode violation place he's chosen as his latest place to stay, he crashes. The couch smells and is a color that can only be attributed to vomit covered by dirt, but he's tired and drained enough that he's asleep before he even lays down.
He had dreams before the war, of random shit, stupid shit, Steve getting the shit beat outta him. He thinks they changed during the war, but the holes in his memory keep him from remembering too much. Hydra's memory wipes had succeeded in doing a lot of things. He had dreamed as the Winter Soldier too, of things, things that Hydra wiped from his mind. Bucky can remember the fact he dreamt, that those were erased along with everything else whenever Hydra felt like it.
The Winter Soldier had dreamed of Bucky Barnes, of Steve Rogers, of Captain America and the Howling Commandos.
Bucky Barnes dreams of the Winter Soldier. He dreams of Hydra, of the experiments, of the training, of the missions. He's aware now though. He can think as his arm raises the weapon and he stares down the sights. Bucky is aware and there is nothing he can do as the Winter Soldier does as he is told and completes the mission. Bucky Barnes dreams of the holes in his mind.
When he wakes, he is drenched in sweat and breathing harder than pre-serum Steve ever had. He hunches over and rests his arms on his legs, the left one shining brightly in the faint light of the moon. Bucky flinches at the sight of it and the memories it stirs. After a few second, he stands and grabs his coat, heading back out into the warm night to walk.
Walking instead of sleeping becomes Bucky's new thing. He's spent enough time as the Winter Soldier, he doesn't need to be one while he sleeps. He still doesn't know what it is. He fears it's a result of Hydra messing with his brain, signs that he's still the Winter Soldier, not Bucky Barnes.
He keeps walking. He stays away from Steve, because he can't face Steve until he figures out who he is. And he tries to figure out what it is.
Somehow they all end up spending more time at the tower than they do at their own places. Even Bucky, who spends the rest of his time at Steve's and doesn't spend enough time at his own place to even bother keeping a pair of clean socks in the dresser. He's not sure how it happened, but he's there and making jokes with Natasha in Russian and marathoning seventy years of pop culture with Steve and whoever else joins in.
Everyone uses the kitchen and Bucky joins in one day when Steve's trying out some new food he's just discovered. "Do me a favor, Bucky, grab the bag of peas out of the freezer."
Bucky doesn't even think about it, he turns to the freezer and opens it. The cold hits him in the form of a chill that immediately settles into his metal arm. The sight of the rime on the food that's been in there since godknowswhen looks so much like the inside of the cryogenic chamber that Bucky forgets about the peas. The door slams shut and he leaves the kitchen.
It takes Steve a few seconds to confusedly call out, "Bucky?" He's already out of the kitchen though and seeking something warm.
He doesn't open the freezer after that, and Steve doesn't ask him about it.
Bucky ventures into the gym after a few too many days of sitting around without working out. Steve and Stark dance around each other in the ring. Stark knows how to fight and doesn't need the suit to hold his own against the cap, at least in a friendly spar.
Bucky starts clapping slowly as the two break off and turn to him.
"You know I had him on the ropes," Steve says.
"Sure you did, capsicle," Stark tells him, his words malformed by something in his mouth. He turns to Bucky and spits out the blue rubber. "You wanna go a round?"
It's the same this time as it was in the store. Bucky is in Russia, stuck in the chair in a hydra base, the mouthguard shoved between his teeth.
"Hey, grandpa," Stark says, snapping his fingers. It takes him all of two seconds to realize to distant look in Bucky's eye.
A few more seconds and Bucky manages to push aside the past that's brushing up against the present. He's cold. The sensation of electricity travels over his skin. He clenches and unclenches his fists and leaves.
Stark's voice calls out quickly for his butler. "Jarvis."
Bucky's out of earshot before he can hear Jarvis's phantom voice answer. Disoriented by nothing more than his own mind, he stumbles into the elevator and slams his hand down on the button. When it starts moving, it's like he's falling all over again. The door opens and he stumbles out, loosing the metal wall that had kept him from tumbling forward.
Bucky hits the ground, and he rolls. He's still crouched when his back hits the wall, his arms raise to cover his chest and face. He's ready to fight. He doesn't have to though, and that realization comes with a deep breath.
Everything's shaking and weak. Even the metal arm feels like it weighs a ton. There is a tightness in Bucky's shoulders, a tension that keeps him from falling apart as he stands. The hallway feels longer than it ever has before, but Bucky eventually reaches his room and collapses in the bed.
The air inside is warmer than the rest of the tower, but it still takes a while for Bucky to realize that. Even the soft comfort of the bed is something he has to force himself to focus on.
"Sir," Jarvis says, his voice emanating from several different points in the room, "Steve Rogers is approaching your room. Would you like me to disable the elevator."
Bucky blinks. "What?"
"Mr. Stark has asked me to locate you within the tower," Jarvis says.
"No, Steve," Bucky says, sitting up to stare at the air vent, "why would, what?"
The door rattles. "Bucky," Steve calls, "hey, you in there?"
"Steve?" Bucky responds, but his brain isn't working and the locked door is stopping his thoughts as much as it is Steve.
"Damn it, Jarvis, open the door," Stark shouts. There's a mechanical noise as the door opens, knocking Steve off balance before he catches himself with flailing arms. "Thank you, Jarvis," Stark quips, then falls silent. "I'm just gonna leave," he says, and quickly does so.
Steve raises his hand to call Stark back, then turns to Bucky. He rolls his shoulders and then sits down on the edge of Bucky's bed. "I'm not a fan of the cold either." Steve scratches the back of his head. "Stark's had Jarvis rig the tower."
Bucky rolls his own shoulders, feeling the metal shift and click with the movement. His heart's still beating like nothing else and it feels like his body's a car that's ready to fall apart. It's not Steve's fight though, and Bucky can't help but see the skinny kid from Brooklyn at the foot of his bed.
"It was the mouthguard," Stark throws in from the door. Both Bucky and Steve turn to him, and when they do, he steps into the room. "I read your file," Stark says, and makes some kind of hand movement to minimize the statement. "Steve did too. We all did actually. Lots of interesting stuff in there."
"Stark," Steve warns, his posture shifting to the super soldier that he's become.
Stark crosses his arms, then scratches the side of his face, then crossed them again before he points at the both of them. "I know this is Cap's line, but we're with you till the end of the line."
Completely confused Bucky turns to Steve. "What does that mean?"
Steve's still staring at Stark, brow slightly furrowed.
Stark closes his eyes and takes a deep breath. "I'm so going to regret doing this," he mutters, then looked up. "Do you remember the events in New York, with the alien invasion?"
Steve's confusion though gives way to shock at that. The revelation is not something Bucky shares, so he tries to remember what he's heard about the Chitauri invasion. "Some wannabe god opened a portal above your tower."
"Yeah, well, another idiot thought it'd be a good idea to nuke the city," Stark says, and blows out a hard breath. "I sent it through the portal, saved the day and all that. The suit cut out though, when I was on the other side, so let's just say I know what it's like to feel helpless."
Bucky's stunned, and not quite sure what to make of Stark. Whatever magic spell though Stark's moment of share time had created is shattered when he opens his mouth again. "New house rule, no mouthguards around Barnes and temperature control in all the rooms." He doesn't look at either Bucky or Steve. "Jarvis," he shouts as he leaves, "I want the freezer rigged so it doesn't open while the bionic man's around."