Disclaimer: Nothing is mine, save the plot.

Rating: PG 13 for language.

Summary: Captain America is always leaving people behind. He's used to it. What he isn't prepared for is how people leave HIM behind. And by people, he means Tony.

Author's Note: I wrote this before the Civil War movie came out, and I really did not like where the movie went with the character portrayals, and since canon is so divergent with itself anyway I said screw it and decided to stick to my vision of things following Joss Whedon's Avengers 2 mixed in with a bit of the comics. Read at your own peril!

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By Kasmi Kassim

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Gravity

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Part 1

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Captain America is always leaving people behind. He's used to it. Moping won't bring Peggy back, so what's the point? He's made new friends, maybe a new life, and tries not to mope too much about love. It's not so bad.

What he isn't prepared for is how people leave HIM behind.

Clint is the first to retire. It comes after his little hiatus, which no one really questions, but then Natasha whispers to them that his wife has packed up and left, moved back in with her parents. Took the kids with them. Steve looks worriedly at Natasha, but is surprised to hear that Tony is taking care of it. He sees the two talking one day, Tony in a sharp business suit and half his face behind a pair of sunglasses, and Clint fingering his bow, pretending not to listen.

The next day, Clint comes to SHIELD – or rather, the temporary agency that Fury is running as an "honorary" leader – and resigns.

Fury gives him a stink-eye that can best be described as his most heartfelt, and Steve pulls him into a hug. Natasha exchanges a long look with him, and Tony bumps fists as if he hadn't used his painful experience with Pepper to help him make a life-changing decision.

Natasha's retirement is sudden, but unsurprising. Tony claims that he thought she would be a cyborg forever, but they all know that his barbs don't quite reach his eyes when he calls her cold-blooded, just as Natasha's voice holds no sting when she curses him in Latin.

They drop off the radar, Nathasha and Bruce, and Tony complains loudly about it, but gives them a home and a sumptuous dinner when they show up at his door for Thanksgiving. He stuffs Bruce's pockets full of high-tech gadgets, cloaking devices. Bruce almost chokes, and holds onto Tony's hand like a lifeline, and Tony lets him hold on as long as he needs to. Natasha touches his arm and gives a smile that is as tender as it is knowing, and he hands her a keycard and shoos them away both, while Steve stands at the porch waving.

Tony doesn't retire. Rather than to let other parts of life pull him gently away from the Avengers business, he lets the other facets of life glance off of him while he soars red and gold. Steve realizes only too late how he has selfishly accepted this as normal. Because this is his life, yes, but not Tony's. Tony has a life outside of fighting, always has, and deserves to. His life has always been ten times the speed and glamor of any other person's, but he throws it down to come flying with Steve and give him backup and fix his armor. Steve is jarred by this realization when he walks in one day to hear Rhodes shouting in the workshop.

"You can't let this die with you!" He is saying. "This is your legacy, Tony! No one has this technology except you, and it's trapped inside your head. Either you share, or you hand it over!"

"That's what Obie said," Tony says, quiet, and Steve stills just outside the door, the tray of coffee mugs in his hands. "That I owe this to the world."

"Damn well you do, since you don't even have the decency to leave your DNA behind." Rhodes huffs. "Though I don't know if that's a blessing or a curse."

Tony just smiles, waves as Rhodes walks away, and Steve appears only after the coast is clear.

Tony looks at him with a cheerful "Hey Cap!" and turns away, and Steve knows a brittle smile when he sees one. He sets the coffee down, and waits for Tony to approach with averted eyes, looking busy.

"You don't owe anyone shit," Steve says quietly. "Anyone who disagrees can get their asses off your power grid and turn in their Stark technology and go fuck themselves."

Tony's laugh is surprised, genuine, and a little bit broken. Steve watches, arms crossed, like he's guarding the workshop from the world.

Steve doesn't dislike Rhodes, not at all, but at that moment, he dislikes him very much. Rhodes is a military man, more so than Steve; he follows orders, and when its' between that and Tony, well, he just left Tony smiling heartbroken, didn't he?

They can part for all he cares. Tony has moved on, his life is different, and if his old friends can't deal with that, well, he's always got his Avengers, and he has Steve. Steve wouldn't turn on him for orders from anyone. He would keep his eyes open to all that Tony has done, and is continuing to do, stretched thin as he is. And if the Avengers all leave him eventually, all retire into homes and family and all that, he would be all right, as long as Tony is by his side. Encased in metal, flying with the power of his sheer genius, surely Tony has a long way to go until he needs to get off the field. And the thought relieves him, helps him hold on, despite the guilt that follows.

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It gets harder when Peggy passes away.

He had been prepared for it, really, telling himself that he would need to let go, and he would do it happily. She lived a full life. The family wouldn't mind him showing up sometimes at the grave – he hopes there would be a grave. But it comes unexpected. He is out on a mission when it happens.

"I thought you might want to know," Sam says into his earpiece, and he can't hear the thud of the falling monster, or the repulsors that come to turn off behind him. He stands in the dusty field that was once a stadium, and vaguely stares as Iron Man wave his hands in front of his face.

"Come on, Cap." Iron Man holds out an arm.

Steve latches on, grateful, and the boost of the repulsors shakes him. Tony doesn't speak.

When they are back at SHIELD, Tony takes to debriefing on his behalf, allowing Steve to get away as soon as he checks in. But he doesn't get the chance, because Fury blocks him on the way out.

"Get out of the way."

"You need to be quarantined."

"I need to get to a hospital."

"You got poison all over your armor!"

"I swear to god, Nick-"

"You think her family needs to see you right now?"

It's like a punch to the gut. And he knows Fury's right.

Hours later, he's sitting alone in a prison cell they call quarantine room, staring down at the floor. He's in thin cotton, his battle gear being analyzed in another lab, and there are cameras on the wall, and a glass window that he can't see through.

The door opens, and Tony steps in, shrieks of alarms ignored, and snaps the door shut.

"Jesus Christ," he breathes, and strides over, looking so sure, even though Steve knows he just looks sure by default even if he has no idea what he's doing – he hopes Tony does know what he's doing, because Steve sure doesn't.

He stares numbly as Tony stands an arm's length away from him. He doesn't ask if he's okay, and he's grateful for it. Tony gestures toward the glass. "I turned off the cameras and activated the soundproofing. No one can see you or hear you for the next thirty minutes." He reaches out and clasps Steve's arm. His eyes are deep, and Steve is suddenly terrifyingly lost in them, and he can't breathe. "Okay?" Tony says, gentle, and Steve nods mutely. Tony steps away, goes to the door, and gives him one last glance. Steve wishes he could say something, anything, but he can't. And Tony sees it, because he doesn't leave. "I can stay, or I can leave. Whichever you want."

Steve doesn't know what to want. "I'm okay." He swallows. "You can go."

Tony slowly pulls the doorknob, and Steve blurts, "wait," and Tony stills. Steve doesn't want to be left alone, but the thought of asking Tony to stay hits him with heavy panic.

At least he's okay for now. Right now is okay. With Tony in the room. He decides to extend the present situation. "Just," he blurts, suddenly exhausted, "stay like this. For a second."

Tony turns and walks back to him, slow, and his eyes never leave his. They're so bright and dark, and Steve feels naked and vulnerable and wants to lean in and let Tony take care of him. The thought blares sirens in his head, and he watches with dread and longing as Tony gets closer. This is a horrible idea. Tony is going to witness every humiliating weakness that's written all over his face, and – and – well, he won't do anything about it, because he's Tony, and Tony is the kindest motherfucker he knows.

When Tony clasps his arm again, looking into his eyes, Steve chokes, and Tony whispers, "breathe."

And Steve hangs his head, his shoulders rising and falling with shuddering breaths, and it's okay, because he's tired, and he deserves to be tired, and no one can see him. This is the quickest and kindest and smartest gift he could have asked for, and again it's Tony that delivers. Tony that stands there, touching his arm, letting him decide what to do. And Steve breathes in, breathes out, breathes in, breathes out, and his body feels wobbly, so he clutches the air, and Tony's other hand is already catching him, his grip startlingly strong. It gives him permission to hold onto him while he falls, and falls, and if his voice tears out of his throat like an animal, well, it's muffled into Tony's shoulder, so it's okay.

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"Iron Man! On your six!"

Iron Man doesn't turn, or move at all. He stands still, and Steve throws his shield at him, narrowly missing him and hitting the creature that was sliming its way up to him. "Iron Man!"

"Aye, aye, Captain."

Iron Man then takes off, rejoining the fray as if nothing had happened.

Nick is not happy during debrief. Tony shrugs. "The sky was pretty?"

Steve nudges him back against the wall when Tony makes to leave. "What is it, Tony?" his voice drops. "What's wrong?"

"Nothing."

"Tony."

"Give it a rest, Cap, I was just tired."

Steve stares, searching for the truth, and Tony rolls his eyes, thumps his head back against the wall, and stays there, staring at the ceiling. Steve finally steps back and lets him go, feeling strangely betrayed.

It happens again, more urgent, more desperate. This time it's Sam's life that's in danger, and Tony doesn't fire up the repulsors to catch him. He just stands there, watches him fall from the sky. And at the last minute, when Steve feels like his legs are giving out under him, his lungs bursting from the hopeless sprint, Tony finally streaks across the sky like a shooting star.

"You motherfucker!" Sam half-whoops, and Tony chuckles.

"I got you, bird boy. Just don't play with the grownups next time."

"Screw you, Stark."

"Language."

Sam doesn't seem to mind, but Steve does. He charges into Tony when he's about to leave after the debriefing. "What was that about?"

Tony raises an eyebrow. "Can't let the flying man have some fun?"

"That was dangerous!"

"I know, Cap." Tony smirks. "Just like it's dangerous to go flailing about with creaky metal wings."

"What is wrong with you?" Steve explodes. "I want the truth, Stark, this isn't a game-" his voice trails off as he realizes that Tony is watching him without a change in expression. No answers, no hardening lines on his face. Just…watching.

Finally, Tony looks to the side, and Steve braces for the snide remark, is ready for it, but it doesn't come. Tony just turns and walks away.

An hour later, the medics grab him in the halls in panic. "His heart stopped," one of them says, covering her face with a groan. "He barely crawled out alive."

Steve's vision grows narrow. He stumbles out of the ward, heads out into the cool morning mist of downtown New York. The dazed fog clears his mind, condenses into a ball of seething fury. He runs all the way to the tower as the sun rises above the morning mist.

Tony is in his workshop, taking off his gauntlet, when Steve storms in. "Why didn't you tell me?" he shouts, and Tony looks at him again, and he looks so defeated that Steve wants to scream, shake him, anything to get that fight back in his eyes. "Why did you just stand there and take, my," he breathes, and doesn't know how to continue. "Why didn't you say something?"

"What, next time I'll be needing a permission slip too?" Tony sits up from the chair he was sinking into, and holds Steve's gaze for a terrible second. "I don't report to you, Rogers." He tosses the gauntlet onto his workbench and walks to the door. "I'm done here. Friday, finish the repairs by tonight. You know your way out, Captain." He doesn't look back.

Steve stands alone, feeling sick. Tony is right. He doesn't owe Steve any justification. Steve doesn't get to go through his reasons and decide which ones are permissible and which aren't. He should have checked himself, should have asked. He can't ask Tony to be accountable for his own temper. The knowledge that he has wronged Tony feels like a kick in the chest.

He spends the night seated on Tony's couch. Tony doesn't come back.

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Bruce surfaces in the tower. Natasha is somewhere, he says evasively, and says he'll only be staying until she comes for him. Steve looks at him steadily, and Bruce evades his gaze.

Tony doesn't give him the look. He doesn't even seem to wonder. He moves, arms thrown forward, pulling him into a hug that smoothly transitions to him dragging Bruce around the renovated tower, pouring vocabulary and ideas on him that only Bruce understands, and pushes him into his old lab and rooms and instructs Friday to take care of him. Bruce's shoulders sag and he breathes slowly out with a tentative smile, and Steve wonders how Tony manages to do that without seeming to care at all.

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Pepper leaves more and more. People, among other things, seem to peel away from Tony's life like pieces of the armor, leaving him bare as he brims with the smell of winds and sizzle of smoke.

He hears Tony and Pepper arguing for the fourth time that week, and it sounds more like a screaming match than an argument. "It's always them first," Pepper is shouting. "I'm always second to you! I'm always your PA!"

Tony's hushed voice placates her, soothing her panting. Steve turns away, pretends not to see as Tony ushers Pepper out, whispering about the Maldives and the beach. The next day, Tony Stark is all over the news. He is engaged.

Steve braces himself for Tony's resignation. They can still meet and be friends outside of Avenger business, after all. As a friend, he makes an effort to visit Tony more often, especially since all the Avengers have now left the tower except Bruce. Tony welcomes him every time he shows up unannounced. They grab lunch, Tony tests tensile strength with Steve, they spar and laugh on the mat, sweaty and winded.

One day he walks in on Tony in his workshop when he's hooked up to some sort of wiring system. He gapes, wondering if it's another Ultron fiasco at work, and when their eyes meet, Tony doesn't explain. He stares back, defiant, and Steve's heart hardens with dread. He approaches like a fighter, and Tony's body language answers in kind. Steve stands in front of Tony. "What is this?"

"Nothing you need to know about."

Steve's eyes sweep over the wires surrounding Tony, connecting into Tony's veins. "Can't let a friend in on a secret?"

"Nope." Tony briskly starts pulling the wires out of his flesh, and Steve grabs his arm. He picks up clean cotton pads from the metal tray to the side, wipes each spot methodically to minimize risk of infection, and all the while cannot believe that his team has a man that flies around in a metal cage that doesn't even know – or care – to clean his wounds properly. He kneels by Tony's reclining bench for a better look.

"Do you remember Ultron?" he doesn't look up.

Tony flexes his hand. "Sure."

"Wanda told me that you wouldn't take care of it."

"Huh."

"Do you know what I said to that?"

Tony doesn't answer. Steve wipes away the last of the blood. "I said she doesn't know what she's talking about." And maybe slipped his first name to the crazy mind control girl while defending him, because Tony might be an idiot, but he was Steve's idiot, and no one else got to call him crazy.

"Yup, that's – okay. Yeah." Tony pulls his arm out of Steve's grip, and Steve leans forward into Tony's personal space. Tony blinks at him.

"Because I trusted you."

Tony looks like a fish out of water, and Steve knows that he feels like one too. "I trust you. Can you answer me back in kind?"

The silence is long. Tony's coiled with tension, himself at war. Steve doesn't know whether to be sad or relieved that he can read him so well now, and resolves to take the war out of his hands because for Tony, he will be the bad guy. He looks up at the ceiling. "Friday?"

"Yes, Captain."

"What's Tony doing?"

"I'm right here, you know." Tony sits up, bolt quick.

"Testing his heart, sir. There has-"

"Mute."

Steve turns a stunned gaze on Tony, and Tony's posture hardens. Steve waits.

Finally, Tony slumps. Steve knows surrender when he sees it, and isn't glad in the slightest.

"I can't fix it," Tony says, weary, and Steve feels unanchored.

"I thought you went through surgery?"

"Yeah, Cap, it's a heart that's been through a lot. It's older than a lot of hearts."

And it hits him, this hammer of mortality, and Steve is left dazed and sinking. "How long has this been going on?"

Tony's fingers hover over his keyboard. "Since the surgery."

The horror morphs into realization. "You should have left it in," he whispers, a lingering question.

Tony shakes his head. "It's done. Anyway, I don't look like a flashlight anymore." He tries to smile, but sees Steve's expression, and gives up. "It's fine."

Steve yields at last because he doesn't know what else to do. He has to trust Tony again. And truth be told, there is no other option.

Steve wants nothing more than to hate Pepper that very moment. He knows how Pepper used to eye that arc reactor, how she used to push away the Iron Man suits. How she would leave Tony shaking and sweating in bed, reliving New York all over again, because she couldn't deal with having to see his Iron Man suit in the bedroom. Couldn't see past the suit to find the man that needed her most. And instead of her coming to soothe him, he went to save her, he threw his arc reactor away, he blew up his Iron Man suits, he erased the scars that made him what he is today. Steve cannot understand how Pepper can have so little regard for what has protected Tony from Loki's brainwashing, the terrible mark of hope that pulled him out of the darkest caves. Tony calls it a brand, a reminder of the blood on his hands, and Pepper sees it as a horrible disfigurement, a proof of his torture and suffering. But Steve sees in it a start of an incredible journey, the death of one man and his rebirth, as he rose above the ashes of his own wrongs and moved heaven and earth to save the world and the woman he loved, even if they both turned their backs on him. Steve can't understand why anyone would be less than awed by that blue beacon of Tony's heart.

He wishes the arc reactor back. And if he can't have that, he hopes, somewhat viciously, that Pepper makes Tony happy with everything she's got. Maybe he hopes it because he knows it won't happen, and he can't bring himself to feel very guilty about it.

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Steve begins to visit more often. Tony always welcomes him with a surprised smile, and Steve smiles back, wondering how he or anyone else could have thought Tony Stark heartless or selfish, when he welcomes a man who just takes and takes from him with such endless generosity.

Tony begins to end their sparring sessions quicker. Steve pushes him; he wants him to be able to take it, he needs to see that Tony can laugh and hit back and call him a jerk. At first Tony seems to be up for it. But one day, Steve throws him a little too hard, and Tony lies there on the mat, gasping at the ceiling. His face grows sickly white and sweat beads down his face, and Steve is bent over him, clutching at his shirt, screaming for JARVIS, FRIDAY, anyone.

The in-house medics arrive only after Tony has regained his breath and started cracking feeble jokes, and Steve sits back white and trembling once Tony is ushered away to the medical facilities downstairs. He doesn't move until Natasha materializes and puts a hand on his shoulder.

"What's wrong with him?" He wants to lean into her touch and weep with relief. He feels like he's finally found a comrade, one of the few people that understand Tony Stark, don't demand things from him in return.

"He's got a damaged heart. It's bound to give out sooner than most people."

He wants to shout at her, to push the cruel truth of her words back into the depths of ignorance. He wants to shout where she has been. Why she hadn't been there for Tony, when he needed her, just as he had needed Pepper, Rhodes, Bruce, Clint.

Instead he stumbles to his feet, stares at Natasha, and asks her for a spar. She obliges, and they don't separate until they are both panting and slumped hours later in the dark hours of the night.

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To Be Continued