In early spring, while he is reading The Hobbit/, he feels the floor beneath him vanish and he is falling falling falling - he lands on his feet in a lab and there are four people present: three men, one woman. One of the men has his own face.

"Well, this is awkward," one of the men says while he stares at the one with his face, with hair shorter than he's had it since the war. And then, "Oh, shit," the same man speaks again. "Please don't be a Winter Soldier."

And that – he glances over. He knows that face. "Stark," he says, "I know I killed you."

This is not a hallucination; he knows how those feel. Nor is it a dream. And he fell.

"Shit," Stark says again.

The man with his face is tense, body held like a coiled spring. James keeps himself loose.

"Um," the woman says. "Oops."

And then Bucky walks into the lab. "Stark," he's saying, "time's up –"

James looks at him and it feels like he's breaking all over again, mind gone white.

.

Bucky is – Bucky –

Bucky takes him by the hand and leads him to the roof. James has no idea what to say, where to even start, and Bucky lets him keep his silence, just settles next to him.

James doesn't ask about the arm. Doesn't ask why Bucky moves the exact same way he does. Doesn't ask how he's alive. How the man with his own face is alive.

He feels the rage coming back. Why is this Bucky alive when his isn't?

He lasts three days before Bucky pulls him to the gym. Three days of avoiding the man with his face, the scientists, the spies. Three days of following Bucky around like the ghost he spent 50 years being, of watching the same programs he watched in his own shit apartment in New York, of eating the same take-out (ordered by someone called Jarvis, who calls James 'Mirror Captain Rogers' , probably because that's what Stark calls him), of trying not to scream and kill every single person in a square mile radius.

"Fight me, Stevie," Bucky tells him, smirking that infuriating smirk from when they were boys.

James - Steve grins back at him and attacks.

It's the most alive he's felt since he fell after Bucky. He doesn't hold back at all, doesn't shy away from the rage and the hate and the pain, and Bucky hits just as hard, moves just as fast, and Steve punches and kicks and dodges and finally they're on the ground, bleeding and bruised and broken, and he does not know, will never know, who moves first – but he's kissing Bucky, sobbing and laughing, and Bucky's holding him and he's holding Bucky, and he just wants –

He should have died in the mountains with Bucky. Bucky shouldn't have left him alone.

They don't leave the gym until after dawn and Bucky leads him back to his room (the one he's sharing with the man with his face), strips them both, shoves him into the shower, and climbs in with him.

They don't talk. But after, Bucky drags him onto the bed, pulls the blankets up over them both, and says, "Sleep. We both need it, Steve."

"Okay," he says. He doesn't expect to actually sleep, but he wakes up that night, with Bucky sprawled over him, and he feels so safe, so warm, so alive.

.

Stark sits everyone down to explain why they have to send Steve back to his own world.

He doesn't want to go back. There is no Bucky there. The man with his face is glaring at him while he holds Bucky's hand beneath the table

But if he stays, Stark says in that rambling, nonsensical way of his, then it's entirely possible that the universe will implode. Stark's honestly not sure. But it seems foolish to risk it.

He is holding Bucky's hand. Seventy years after Bucky died because Steve Rogers failed, he is holding Bucky's hand. Bucky's alive here.

The man who was once Steve Rogers cannot risk a world where Bucky Barnes is still alive, so whenever Stark and the other scientists find a way back, he will go.

.

Another two weeks pass. He spends them with Bucky. They talk some. In the dead of night, he confesses into Bucky's skin everything he never said. They spar again.

Once, they compare Hydra stories. Later that same day, they talk about their revenge. Bucky smiles, bright and fierce, when he talks about how Pierce begged for his life.

He spends one morning trying to figure out where their worlds diverged. He wants to demand of the man with his face why he didn't follow Bucky, but he doesn't. He doesn't think he could stand the answer.

.

The night before he has to go back, he cries himself to sleep in Bucky's arms. Bucky holds him and they both pretend they're young again, untouched by war and time and oceans of blood. It wasn't that bad a life, what they had. They were together.

If he could go back –

But he can't go back. Not to his Bucky.

So while Stark and Foster and Banner are setting everything up, Steve wraps himself around Bucky and confesses, "I miss you so much, Bucky." And then, what he's absolutely terrified of: "You'd hate what I've become."

And Bucky – with his eyes closed, his forehead against Bucky's, Steve can almost pretend that they're back in their shitty apartment, young together again, and Bucky says softly, "No, I wouldn't." Steve can feel him breathing, feel his pulse, hear his heartbeat, and he says, lips brushing against Steve's skin, "It doesn't matter what happens, what you do, what you're made into. I'll love you 'til the end of the line, Steve. 'til the end and to whatever comes after."

He can't let go. He doesn't know how long he can't let go, but he eventually he steps back. He walks to the portal and he steps through, back to a nothing world.

The Hobbit is on the floor where he left it. All the perishable food has gone bad.

He hasn't killed anyone in seven years. But he's in a world without Bucky Barnes again. He's in the world that let Bucky die.

He leaves his apartment with the taste of Bucky still on his lips.

.

He dreams of Brooklyn, of Bucky laughing, of the Grand Canyon and Bucky talking about geological ages, of sketching Bucky asleep and awake and alive.

There are so many people alive who aren't worth the air it takes to keep them that way, and Bucky's lost in the mountains, barely a footnote in history when he was the greatest person to ever live.

And Steve –

Well. He's still angry about that. He's got nothing left but the rage, sunk deep into his bones, and stirred up again because there's a Bucky somewhere. Just not here.

He should have died in the mountains with Bucky. Wishes, with every breath, that he had.

He loses himself in the hunt, in the kill, in the retribution, and every time he closes his eyes to sleep, he prays for Bucky to forgive him one day.