Time is relative, okay? It can stretch and it can squeeze, but... it can't run backwards. Just can't. The only thing that can move across dimensions, like time, is gravity.
I'm drawn across the universe to someone I haven't seen in a decade, who I know is probably dead. Love is the one thing we're capable of perceiving that transcends dimensions of time and space. Maybe we should trust that, even if we can't understand it.
~ Brand, Interstellar
"I hope you appreciate the irony," Tony said. "Twenty-five year old me would not approve. But here we are." He leaned forward over the worktable and met Steve's gaze square on. "This is me asking, no, begging. Don't go through with this."
Steve's jaw did that clenchy thing he did when he was stressed or holding back. It had been constant for the last six months. If not for the serum, Tony would’ve been concerned about him cracking a molar.
“I know what I’m getting into,” Steve said. "I've been there before. I've lived it--I know exactly what's going to happen, and when. I'm just changing this one thing--"
"This 'one thing' being saving a man who goes on to have a direct impact on the next seventy years of history. Butterfly effect," Tony shot back. "I know I made you watch the movie."
"What HYDRA did to Barnes was terrible. Inhumane. It sucks," Tony said. "But sometimes life isn't fair--"
"Not fair?!" Steve slammed one fist down on the workshop table. There was a sharp snap and a crack appeared in the opaque glass. Steve didn't flinch. "Bucky was tortured for seventy years. They twisted and broke a good man, my best friend. All those people he was made to kill—" He stopped and shook his head with a frustrated inhale. "If I have even a slim chance at setting this right, I have to take it. It's my duty to do no less."
They glared across the workbench at one another. And to Tony, the gulf between them had never felt wider. Sure, they'd had their ups and downs the last two years, but the last time Tony remembered Steve being this angry with him was while he was under the influence of Loki's scepter in the helicarrier.
Come to think of it, there was an alien device in the room here, too.
"And you agree with me," Steve continued, his voice softer. "Or else you would have told Thor about the time-travel pod."
Tony glanced over his shoulder at the thing. The Avengers had been on the hunt through HYDRA bases for Loki's scepter. They still hadn't found it, though Thor said they were getting close.
Then, two weeks ago, Tony recovered something from a HYDRA basement that had definitely pegged as 'not from Earth'.
It was a roughly baseball size sphere which glowed an evil vivid blue. Tony’s own curiosity had been his downfall. He'd taken kept the discovery secret and taken it for study – just for a couple days, he'd told himself – before he let Thor return the thing to Asgard.
HYDRA scientists had been working on a way to activate it, but they didn't have Tony's brains or knowledge he'd gleaned from Chitauri tech. It took him a whole day to figure out the sphere’s secrets. If JARVIS's readings were correct, it had the power to open a stable portal into space-time, and transport someone through.
Then Tony made his second fatal mistake: He'd told Steve what he found.
And of course, Steve knew exactly how and when he wanted to use it.
"Do you love him?" Tony blurted. He'd been sitting on the question ever since the helicarrier's crash into the Potomac. Now it came spewing out of him like a bad batch of oysters. "You and Barnes, were you together?"
Steve jerked back like he'd been slapped. "He's my best friend. He was there for me when I had nothing. He's saved my life more times than I can count—"
"Not the question I asked," Tony said, and was glad that Steve had the decency to meet his gaze. "Were you more?"
They probably should have had this talk awhile ago. Yes, he and Steve had been together for going on two years, but much of it had been long distance. Tony had his work, Steve had SHIELD. (Until he took down SHIELD, but from then on he was more distant than ever -- on a futile effort to find Barnes before various government agencies did.) But they'd never had the ex talk. At the time, Tony had been glad. His list was long and extensive, and he figured Steve's past was too painful.
Steve closed his eyes and looked away. The answer was clear on his face.
It hurt. Just like someone had ripped out his old arc reactor. Tony braced himself on the workbench.
Smooth, Stark. Go out of your way to activate a device capable of ripping a hole in the space-time continuum just so your current boyfriend can reunite with his ex-boyfriend. Tony knew he was a self-destructive son of a bitch, but this was a whole new level.
His reconstructed heart was breaking. He turned away from Steve.
"Once you take that trip," Tony's voice was soft in the silent room, echoing in the wide space between them, "you'll have to return to the present the old-fashioned way. We don't know where HYDRA picked up the time travel pod -- and it only moves objects through space-time backwards. So, if you want to come back you'll have to go through it all again -- the Valkyrie, the Chitauri invasion. I won't know you in the new timeline, or remember we were ever together. You could just... never mention it. I'd never know. As a way to break up, it is very...very clean."
"Is that what you think? Tony..." Steve crossed around the workbench with super soldier speed, and gripped Tony by the shoulders with his big, warm hands.
It was the first time he'd touched Tony in weeks.
Tony should have shrugged him off. But he missed Steve’s touch--was starving for it. When Steve kissed him, he couldn't pull away.
Besides, he had to get close. Parting his lips, he deepened the kiss, using every dirty trick he knew to make the moment linger.
Steve was wearing a replica of his WW2 uniform in preparation for the trip back. Tony's hands smoothed over his chest and touched at the pockets of his red, white, and blue jacket. Just briefly, but it was enough.
Steve didn't notice a thing.
Finally drawing back, Steve cupped Tony's face in his hands.
"I'm not doing this as some convoluted way to leave you. I'm saving Bucky, and then I'm coming back.” Steve stared into Tony’s eyes, gaze soft. “I'm coming back to you, Tony, I swear it."
"Captain America guarantee?" His smile wobbled slightly, and he let himself believe. It was easy to do. Steve's conviction was catching.
"I promise." Steve took Tony's hands and brushed a kiss across his knuckles. “I promise.”
Something in Tony felt like it was breaking. "Don't go," he whispered.
Steve squeezed his hands. "This isn’t goodbye. Tony, no, look at me. I'm setting things right with Buck, then I'm coming back to you."
"It won't be the same."
"It will.” He tried a smile. “Better even, now I know not to take your showmanship so seriously."
Tony broke, clinging onto him in a hug, inhaling Steve’s scent: a mix of leather, the aftershave he wore, and warmth that was Steve’s alone. He wanted to ask JARVIS to lock the doors. Maybe convince Steve to come to bed, or the couch, for one last real goodbye to remember him by.
But Tony was proud enough not to beg for a pity-fuck.
Besides, the moment was ruined when Steve used his thumbs to wipe some of the moisture from under Tony's eyes, and asked, "So, how do I activate the device?"
It was like a splash of cold water to his face.
Tony drew back. Nodded once to himself. Why was he surprised? "It's already rigged to go. Just touch it, fix the time and place in your mind. It can read minds apparently -- fun tech. No way that could go wrong whatsoever."
He stepped aside.
"Save travels, Steve."
Steve looked like he wanted to say something more. Maybe promise one more time that he was coming back. He wasn't. Tony had been around the block a few times and knew the truth. Sure, Steve might intend to now, but once he returned to the good ol’ days… well. He’d be home at last, wouldn’t he? Together again with Barnes.
Turning away, his shoulders hunched like Tony was the one breaking it off with him, Steve crossed the room. He reached out one hand to the device.
There was a flash of white light.
The frozen wind bit at every bit of exposed skin, but like hell was Bucky going to show he felt it. He had his blue winter coat buttoned tight to the top of his throat, which was more than what some of the Howlies had. He’d survive.
Turning in place, he eyed the steel cable that stretched from the anchor point at the top of the ridge behind him, out over the canyon and the train tracks. The wind swayed the rigging, and Bucky figured it was already collecting ice.
At the angle and speed they were going, if they didn't hit the train, they'd smash right into the mountain face. That is, if they didn't just slip off the zip-line on the way down.
Bucky glanced at Steve out of the corner of his eye and tried a joke cover his nerves. "Remember when I made you ride the Cyclone on Coney Island?" Steve had thrown up all over himself, and his date.
He expected Steve to crack and grin and drawl something back. That was the way it went with them – push and pull. Guts and glory.
Instead, Steve staggered in place, reaching out as if to grab hold of something that wasn't there. Bucky turned and caught his arm.
"Whoa, Stevie, you lookin' to faint on me?"
"What—Bucky?" Steve’s blue eyes were wide. Then he turned to stare around at the ice-crusted ridges. For the life of him, it looked like he was seeing the view for the first time.
Bucky stepped closer, growing alarmed. Maybe this was more than just pre-mission jitters. Maybe Steve was sick. Could he even get sick, with the fantastical serum they’d pumped into him?
"You alright, pal?" he asked.
"Huh?" The confusion faded from Steve’s eyes. He gave his head a shake, then straightened, squaring his shoulders. "I'm fine."
"You don't look fine."
A little unease returned to his expression. "Look, Buck...” Steve glanced to the train tracks, the steep rigging, and swallowed. “I don't think you should go on this mission. I'm switching you out with Gabe."
"The hell you will!" Bucky exclaimed, then stepped closer. "I've been training for this." It wasn't much -- working with a line strung across high trees, but it was something. "And I was the best sticking a landing, next to you."
"I got a bad feeling. I need you to stay behind, watch my six."
Steve was interrupted by Dum-Dum’s call that he'd spotted the train. Bucky shot Steve an angry look, then moved deliberately to the zip-line. The order of decent had been hashed out when they’d come up with this crazy scheme last night -- Gabe was going to be right behind them both. No way was Bucky letting Steve go alone.
He didn't miss Steve’s agonized look, but Bucky ignored him. It wasn't like Steve to get all broody over his men, and Bucky wasn’t about to let it become a habit: It wasn't right thinking in a commanding officer.
Luckily, Steve pulled his head out of his ass and took the line first. Bucky waited until the count of ten to go after him.
The drop was even faster than he thought it would be. Bucky might have yelled, but the wind whipped his voice away. The train was a dark smudge in the distance, quickly growing larger. A black line across a vista of snow.
The Cyclone on Coney Island had nothing on this ride.
He was more than a little surprised when his feet actually touched down on the top of the icy train. Then he was too busy to think about what a lucky bastard he'd been. Gabe barely made it right after.
Ducking to shield himself from the wind, he exchanged looks with Steve, who hesitated, and looked like he wanted to tell Bucky to hold back again.
Gabe found the access panel to the car below, and they went down.
After that, it was gunfire and madness. Bucky swore he’d never seen Steve move so fast -- he performed some kind of fancy kick and sent a man straight through the glass window.
The plan was for them to separate to search the cars faster, but Steve stuck to Bucky like a burr in a wool sock. Irritated, Bucky gestured for Steve to stick to the plan.
“Take the right,” he said. “I’ll search the next car.”
"No," Steve snapped. "We're finding Zola together."
Pity. Bucky had been sort of looking forward to the chance at getting the chubby-faced scientist alone to himself for a minute. Maybe give him a taste of what it felt like to have needles stuck in him.
The door to the next car slid open, and an armored man wearing two guns like suit-sleeves stepped forward. Bucky ducked one way for cover, Steve the other.
Bucky was the first to fire back, cursing to himself when his pistol ran empty. He glanced across the aisle to Steve, who stared back at him, white as a sheet. Like he was watching a slow-motion horror flick.
Not a good time for Steve to get nerves. Bucky gestured for Steve to throw him his extra pistol -- he was the better shot, and they both knew it.
Steve shook his head, jaw clenched, and stood to toss the shield.
"No!" Bucky yelled.
The shield went flying, knocking the HYDRA gunman for a loop, but not before he got his own shot off. The blue energy blast went wild, exploding right before Steve's feet, and ripping open the train car like a tin can.
The force of the blast knocked Steve back one step too far.
"Steve!" Bucky half-rose, arm extended. Steve reached for him, red gloves brushing the tips of Bucky’s fingers.
Then Steve was falling, mouth half-open in surprise. Out of the train and down, down, down to the canyon below.