They make their way slowly across the loft, Tony's free hand on Steve's shoulder, Steve walking backwards, taking utmost care to keep his fingers steady inside the arc reactor casing. It's about as awkward as anything can be. Tony is moving a little faster than Steve, and steps on his toes a few times. It reminds Steve of the first times he went dancing, except he's supposed to play the part of the dame, just following Tony's lead. Not something he's used to.

Steve thought they'd be headed to the large open lab area close by, but instead, Tony guides them verbally and with directing touches towards the elevator.

"Two more steps, there, through the doorway, and we're in."

As the doors slide shut, a disembodied voice greets them: "Welcome back, sir, Captain."

"JARVIS! Just the AI I need," Tony replies cheerfully.

"Your private workshop, I presume?"

"That would be correct."

They move down a couple of floors, to one that Steve hasn't visited before. The doors open to reveal a workshop that's not very different from the one above, just even less tidy, pieces of broken or half-finished red and gold things cluttered here and there.

"I must congratulate you on the most creative use of available resources up to date, sir," JARVIS comments as they step out of the elevator. Since they haven't turned around, Tony's now walking backwards, but he still has the lead.

"Why, thank you, J. I do take pride in my ability to improvise under duress. Steve, that way," Tony says, and nods over his left shoulder.

At the corner of the shop that Tony's pointing to rests what looks very much like a dentist's chair. It doesn't take complicated reasoning to work out that this is where he deals with arc reactor related things, and it's not surprising it's not placed in his other workspace for everyone to see.

Tony settles down on the chair, and starts pulling out wires from behind an armrest. He connects one to the reactor, another to the side of the casing, and cuts open the front of his undersuit so he can stick heart monitor leads to his chest, which he does far more routinely than anyone who's not a medical professional has any right to. Steve can't help but wonder how often Tony's been down here, alone, doing this after a mission without the rest of the team even realizing he might not be okay. Before today, Steve certainly hadn't fully appreciated how dependent Tony is on that constantly glowing blue circle.

"All right, JARVIS, full diagnostics. No stone unturned. I need to know what's going on," Tony says.

"Very well, sir."

"Um, should I stop?" Steve asks hesitantly, aiming a pointed glance at his hand, still firmly embedded in the casing.

"No, absolutely not, not before I tell you to. And the less we move, the less artifacts JARVIS will have to compensate for. Won't take more than five minutes."

"Can you actually stay still and quiet for a whole five minutes?"

"Yes, if my life depends on it, and right now it sort of does, so, shush." Tony leans his head against the headrest, and closes his eyes.

For the next few minutes, they just wait, listening to the low background hum of air conditioning and computers and whatever other machinery is running in the workshop. It's almost reminiscent of the raft, except that Steve is standing up, he knows Tony's not asleep, and they're not nearly as close to one another, Steve's fingers their only point of contact.

"I have now finished turning the proverbial stones, sir," JARVIS breaks the quiet.

"Excellent. Show me."

The air next to them lights up with a complicated floating diagram of circuitry that clearly represents the reactor and the casing. Most of it is in blue or green, but some parts around the middle of the casing stand out bright red.

Tony stares at the image with a deep frown, and zooms in on the red bits. He blanches as he takes it in. Steve can feel the thumping beneath his fingers speed up a notch.

"Holy shit, JARVIS, are you seeing this?"

"Indeed I am, sir. It seems you were quite lucky with your improvised solution."

"Yeah, it actually shouldn't have worked like it did. Jesus, that really was just dumb luck. I had no idea. No wonder it was so dependent on the angle. By all accounts, I shouldn't even be alive anymore!"

"Are you going to tell me what's wrong?" Steve asks warily.

"Um, just that there's a little more damage than I thought, but it happens to be located so that pushing at a very specific angle causes a short circuit that sort of goes around it. Not a good solution in the long term, bound to cause even more damage. Already did, in fact, that's why you couldn't let go."

"Can you fix it?"

"Sure I can, just need to replace some wiring. Piece of cake. J, do you think you can emulate what Cap is doing?"

"Of course, although I strongly recommend rerouting power as soon as possible to prevent further harm."

"That's the next item on my list. But first, good news for you, Steve," Tony says. He pulls a robotic arm from somewhere behind the chair, and brings it close to the casing. "Now would be the time when you can let go for good."

"Right now?" Steve asks, feeling that familiar pang of concern at the thought of leaving Tony in trouble.

"Yes. This time, I promise it'll be fine, JARVIS will take over."

"All right then," Steve says, and pulls his fingers out for the third and hopefully final time. The robotic arm moves in with a soft buzz. Tony looks a little apprehensive as it settles inside the casing, but then relaxes and smiles.

"How's that, sir?"

"Spot on. Keep it up."

Now that his hand is finally free, sharp pins and needles stab at Steve's fingers. He flexes them, opening and closing his fist. He's pretty sure he's never held his hand so steadily in one position for such a long time. He can only imagine how much worse it would've been without his enhanced physique.

Tony reaches to grab Steve's hand, and brings it to his lips to press a light kiss on Steve's knuckles. It's a perfectly chaste gesture, but Tony being Tony, he still somehow makes it seem suggestive - something to do with the glance that goes with it. Steve feels his face heat up.

"Poor, heroic fingers," Tony says. "There are worse places to be, of course, but that can't have been easy. Did an excellent job keeping me alive. Now, for a more permanent solution..."

He spends a while studying the holographic diagram, adding notes to it, and calls up another display that shows a magnified view of the casing in his chest, like a mirror. Then, he stands up to rummage through nearby drawers. The robotic replacement for Steve's hand follows his movements seamlessly as he collects his tools and materials and sits down again.

"Here's what I'm going to do. First, a very quick and dirty temporary fix. Will have to go offline for that, should have just enough time to finish it. That'll give me room to make the repairs properly, without any extra appendages in the way."

Tony pulls up a tray, and arranges a few things on it. It barely seems like enough to mend anything, just bits of wire, some tools and a small soldering iron.

"You better hold on to that," he says, and offers the arc reactor to Steve again. "If something goes wrong, JARVIS will tell you what to do."

He doesn't give Steve time to protest, but promptly goes on to disengage the robotic hand and to unplug the reactor entirely. Steve stares at it, resting on his hand, no longer attached to Tony. Somehow, that's a lot more disturbing than it should be, like holding a limb that has been cut off.

Tony pries something open in the baseplate and starts working, hands surprisingly steady. Steve watches, and thinks it's as if he's witnessing someone perform surgery on themselves, although he can't see much with Tony's hands and tools blocking the view. It's incredible that Tony can manage to work at all in such a limited space - his fingers may be shorter than Steve's, but his hands aren't exactly tiny.

It hasn't even been a minute when an alarm goes off, startling Steve out of his introspection. He looks up from Tony's chest, and realizes it's the heart monitor, which has been discretely on mute until now. Steve doesn't need to understand the details to figure out that the loud wail and the flashing warnings are not a good sign. He very nearly panics, then, which is something he's usually not prone to do.

"JARVIS? What do I do? How can I help?" he asks the room around him.

"Nothing, Steve! Stand down!" Tony commands, and now that Steve looks at his face, even though his complexion has gone a disconcerting shade of gray, his eyes are still alert. "Ten seconds," he adds.

Steve crosses his arms and waits.

Tony squints at his displays, adjusts something with hands that no longer seem entirely steady, keeps them in place for several seconds, and finally lets them drop to his sides. The soldering iron he was holding falls neatly into the awaiting robotic hand.

"Arc reactor, now," Tony demands urgently. Steve gives it to him, and he hastily connects it to the casing with the cable.

The alarm fades out, and they're left in silence broken only by Tony panting like he's just finished a decent jog. Color is slowly returning to his face.

"Well, that was fun," Tony comments breezily.

"No, it really wasn't!" Steve declares.

"I must agree with Captain Rogers, sir," JARVIS says. "Unless you are using the word 'fun' in some sense that is missing from all my dictionaries."

"Oh, JARVIS, you disappoint me!" Tony groans. "Try looking under 'irony'? I can understand Cap has problems grasping the concept because it probably hadn't been invented in the forties, but I programmed you better than this!"

"That wasn't irony, you just like flirting with danger and freaking people out," Steve mutters.

Tony ignores that and says, "Anyway, the job is only half done, and the rest of it will be boring, with barely any risk of sudden death."

"You still need my help?"

"Nah, not really, you can saunter off if you've got somewhere better to be." Beneath the dismissive tone, it very much sounds like he'd prefer Steve to stay.

It would be the perfect time to head to the kitchen and pick up something to eat, maybe a coffee for Tony, but Steve can't find it in himself to leave. He makes his way to the nearest chair and settles down, in a very strange frame of mind. He stares at his fingers, and can still feel a vague echo of them firmly pressed against the baseplate – he almost misses having that constant touch to assure him that Tony's all right. He tries to relax. He's spent most of the day in various stages of concern for Tony, ranging from the overwhelming fear that he's dying there and then, right in front of Steve's eyes, to the constant gnawing worry that he won't last long enough to make it back. It's difficult to convince himself that it's all in the past, or will be, as soon as Tony's finished his repairs.

Tony certainly seems much more at ease as he works, poking at the reactor housing, chatting with JARVIS, zooming in and out of his diagrams with lively gestures. Just once, whatever he's doing produces a bleep of alarm and a warning "Sir!" from JARVIS, but he just goes "Oops?", shrugs, and keeps at it.

It takes a few minutes for Steve to wind down again after that. So, despite his continued efforts at not worrying, Steve is still a little edgy when Tony removes all additional bits and pieces from the casing, does away with the cable connected to the arc reactor, and pushes the reactor into its proper place, finally making his chest whole again.

"Ah, there we go!" Tony announces happily. He studies all the readouts for a minute, and clearly satisfied with what he sees, disconnects all the monitoring wires. Then he stands up, stretching his arms. "All better now. And if we ever run into whatever the hell that lightning thing was again, it can shoot as many bolts at me as it likes, not going to cause any damage." He raps at the arc reactor, looking very pleased with himself. "I should send them a thank you note, really. Revealed a weakness that I hadn't realized was there."

Steve gets up as well, walks over, and looks from Tony's face to the arc reactor suspiciously. "You're a hundred percent sure it's all fixed?"

"Yes. Trust me, worrywart, I know these things."

"But Tony, you -"

"J, a little support here?"

"According to all available metrics, you are functioning within normal parameters, sir. There is no need for further concern, Captain Rogers," JARVIS declares. That's probably the most impartial, objective opinion Steve can get, coming from an artificial intelligence – except it's an AI programmed by Tony.

"Okay, I'm happy to hear that," Steve says, but obviously still fails to appear entirely convinced, because the next thing Tony does, he grabs Steve's hand and presses it tightly against his chest, half over bare skin, half over the reactor.

"There, feel it? Ticking away like nothing ever happened. All thanks to you, of course. Without you, I'd be dead several times over. I'm glad I didn't go alone, I did consider doing that at first."

The strong, steady heartbeat under Steve's hand is almost as familiar as his own by now, and yes, it's a thousand times more reassuring than any words could ever be.

"I'm glad I was there," Steve says earnestly. "And if anything like this ever happens again, you can always count on me."

"Excellent, any fingers, toes or other body parts that I need for an engineering project, I'll know who to ask," Tony quips, and lifts his hand from Steve's. "Also, I'd appreciate it if you didn't tell the others about this. I know it's priceless, as stories go, but…"

First, Steve finds that a little surprising, because a tale of the two of them marooned and stuck together with Steve's fingers inside Tony's chest is the sort of thing he'd expect Tony to tell with relish, but then, it does paint him as far more vulnerable than most people ever see him. Steve can appreciate he'd rather keep it between the two of them.

"Fury wants a full report," Steve reminds Tony. "Of course, we can make it a strictly classified one. Wouldn't want anyone to know you actually do have a heart beneath all that metal," he pats Tony's chest lightly.

"You know, you're not even the first person in the world to make that observation. You should ask Pepper about it one of these days. But, anyways, now that we're finally convinced I'm not about to flatline anytime in the near future, how about we celebrate with pizza? I'm starving!"

Epilogue: Pizza

Tony and Steve have finished the pizzas and are working on filling any remaining gaps with ice cream when agents Barton and Romanov storm into the room, taking running steps. They clearly haven't even stopped to shower and change after whatever covert mission they've been on, and they look more than a little surprised as they take in the scene, cozy as it is.

"Sorry, we didn't know when to expect you back so we only ordered for ourselves, and there's no leftovers," Steve tells them.

"So, you're both all right, then," Barton says. His eyes flit from Steve to Tony, and linger noticeably on the glow of the arc reactor, just visible through Tony's t-shirt.

"We came as soon as we could, Fury told us there'd been some kind of an incident," Romanov says.

"Nah, barely worth mentioning," Tony replies dismissively.

"Oh, come on, what happened?" Barton prompts. "The way Fury said it, it must've been pretty serious, I actually saw his eyebrow twitch."

Steve casts a sideways glance at Tony, who just shrugs, a vague smile on lips.

"Well, first, I went jogging," Steve begins.

"And then I took him on a flight," Tony adds.

"Then we dived to go swimming in the sea."

"We also did some sailing. Or rafting. Sort of. Then, I got tired and had a nap."

"And when Tony woke up, we came home and he fixed some stuff."

"And Steve helped. After all this, we were really hungry, and decided to have pizza," Tony finishes, motioning at the table in front of them.

"And that's it?" Romanov says incredulously.

"That's it," Steve says.

Author's Note: And that's it for the story, thank you for reading, hope you had as much fun as I had when writing it! :)