Natasha was lying, or maybe floating, for a long time. On her back, legs crossed and her feet neatly stacked. All she felt allowed to do was stare at the nothing above her, unblinking and unfocused, thinking about love and debts and war and peace.

"Agent Romanoff," said War and Love and Debts and Peace, "you miss me?"

Natasha didn't know why her lips curled up. She didn't look, but felt Tony adopt her position, only the other way around - feet resting alongside her head, head near her feet.

"Am I gonna have to spend eternity with you, Tony?"

"Don't complain yet, I get worse."

Sadness tainted her smile into a frown. "What happened?"

Tony shrugged. "Worried you might get lonely. Plus, I wanted to upstage you."

"You know, I thought if anyone was going to pull the martyr move, it'd be Rogers."

"Really?" Tony hummed. The sound felt, inexplicably, like home - like the tower, like JARVIS and movie nights. "Personally, I've been thinking it'd be a coin's toss between you and me for years. Somehow, this particular scenario- evaded me."

"Why you and me?"

"'Cause we've both got debts to the world that the world would never have let us pay."

Natasha's eyelashes flickered down. Something about this conversation should hurt, she knew that. But all she felt was at peace. "Bruce and Clint would claim debt too."

"But they can live with their debts. We clearly couldn't."

Natasha finally let her head fall sideways, hair spilling back. Tony was looking at her too. "I don't really want to talk about it."

"Me neither."

She pressed her lips together. Tony had a thick full head of sky-black hair that she hadn't seen in years. The wrinkles and smile lines, behind his goatee, were invisible. He looked healthier, more fit - but there was still a blue heart embedded deep into his ribcage. "You look younger."

"I'm a child at heart. You look the same."

Natasha released a breath. "For the first time in my life, I think I am who I am."

Tony's eyes softened. He swept to his feet, somehow making the action seem smooth and all-encompassing. Natasha stared at him. There was an energy and a sureness to his every movement that he was too old and weary to still have.

She side-eyed him as he crouched beside her. Something melodic permeated her surroundings – made the world shimmer and brighten, perked up her ears and her mood. She blinked at him. "What are you doing?"

"It's called music. Do they not have that in the Spy Kids' school for scary redheads?"

Natasha would have given him a response, as colorful as she was capable of, but the music Tony was somehow producing started to become real and familiar to her ears. The first few beats were distorted – but then, the sound smoothed out, every note ringing the clearest she'd ever heard.

Natasha went still. Tony had always been one of the few people able to nearly render her speechless.

"Katy Perry?" she purred, grinning. "I knew it. You were never gonna be able to hide the twelve-year-old girl inside you forever."

Tony extended a dramatic hand. "Natasha, make me swoon," he begged breathily, and she cracked up laughing, couldn't make herself stop.

Tony waited until she was done. Natasha sat up and patted his cheek. "No."

"Nat," Tony told her very seriously, "I look twenty again. If I don't act like I'm high, stupid and have nothing to lose, I'm not doing that guy justice."

"Tony," she returned, equally seriously, "this song includes a lyric that goes 'barbies on the barbecue'."

"I know," he said gleefully, and she snorted and grabbed his hand.

Tony Stark, Natasha reminded herself, was fun. He was a loose, uncoordinated Katy Perry dance-off, a bad karaoke of bubblegum music. He would drag her off the floor when all she wanted to do was lay there and stare at the infinity ceiling. He'd tell the world 'I am Iron Man' just so he wouldn't have to tell them otherwise.

Tony would turn life into a party just because he knew he was dying.

Fallaces sunt rerum species, she'd told him, and it must be so hard to shake the whole double agent thing, he'd told her. You alright, she'd asked, and always, he'd promised.

See you in a minute. Careful what you wish for.

So Natasha held on tightly, and, drawing circles and wheels and swirls all around him, acted like she was high, stupid, and had nothing to lose. She sang 'it's a blacked-out blur' at him, and he returned with 'but I'm pretty sure it ruled'.

It was ridiculous. When it was over, she tapped his chest twice, still breathing heavily.

"Again," Natasha requested, and Tony grinned.

"'We Are The Champions'?" he suggested, and they immediately pulled the same face at each other.

"My turn to pick," she decided.

She found she could manipulate their ears the same way Tony had; before long, they were ringing, something far less obnoxious crooning all around them. It felt like a balm. Tony offered her a half-smile.

"What is this?" he asked.

The downswing of a story that was ending. A heavy mantle coming off weary shoulders after a long day. The morning after the world cries itself to sleep. "Something peaceful," Natasha replied. The final breath of a live worth living. "Going to sleep after the party."

Tony didn't waste any time – before she knew it, she'd curled around him, their hands landing on each other naturally. One of hers on his shoulder, the other intertwining with his fingers. He tucked himself closer, his free hand flying up in-between her shoulder blades. Every step from then on out felt synced – the way one of them flitted away half a moment before the other kicked a foot that way; the way they'd spin away erratically only to meet exactly halfway.

Tony performed a perfect lift not a second after pivoting a knee right off the floor, and suddenly Natasha couldn't keep quiet anymore. She brushed the tips of his fingers, whirling away and then into his hold. Her forehead landed on his chest, his chin resting on the top of her head, and she felt like a little girl again, whole and safe.

"I thought you were gonna live forever, you know," Natasha murmured. Tony laughed.

"I sure didn't. Why did you?"

"Something about you. It's larger than life. Like maybe if I didn't know you so well, I'd wonder if you could rule the world."

"Well, you know-" he said, and suddenly their song was interrupted by another one, something artistic, messy, and harsher. The lyrics promised Natasha 'we could be heroes - just for one day'. "We get one day."

She gave Tony a look. He shrugged. "Blame Pete. I thought teenagers were only supposed to like frivolous pop music, but my kid listens to some weird shit."

The present tense in that sentence seemed to make him happy, so she smiled too. Natasha's song came back.

They weren't dancing to the beat – they weren't dancing to any beat at all. Just moving with each other, against the world – making sure there was still something warm to hold on to. Too fast, at times; so slow as to last forever, at others. The music would swell, and they could drag their feet; the tempo would whisper and crawl, and they could swing and leap to an imaginary one instead.

It was Natasha's song – a collection of fake whispers turned real, tugging them both away, always slightly off-beat. She knew it was reality, because it would never be perfect.

"I never thought you could live forever," Tony mused, inevitably, his way of reciprocating her sentiment. The song quieted a bit. "Most of the time, in fact, I thought we were all on the brink of death."

"You're such a drama queen," she huffed. He didn't reply. "Maybe we all should've paid your drama a little more attention."

"Maybe," he agreed - it sounded like warmth and absolution; unassuming and unapologetic. "Maybe I should've made it easier for the team to listen."

"Maybe," Natasha agreed too. "Maguna?" she asked simply, because it was easier like that, to finally face the unspoken pain in their little bubble.

Tony glanced at her like he wasn't surprised she'd picked up on and used the nickname. "She'll never lack for love and family. Or for any of that other shit kids need so they don't starve to death or something."

Natasha breathed in slowly. "Speaking of family-"

"They're all okay. Everyone made it except us. Promise."

"I'm sorry you only got five years with your little girl."

"So am I."

"You'd be- you are a great dad."

Tony gave her a lopsided smile, and threw her into a twirl.

"Where'd you learn to dance?" she asked, gracefully skidding into a particularly inspired move of his. Not marble, cold and perfect; warm and fun, a family's fireplace at Christmas.

"Trust fund babies come out of the womb signed up for formal dance lessons. Personally, I've always thought my mother had a million less cruel ways to torture some poor liberal arts graduate, but there you go."

"Your mom," Natasha realized, halfway through his rambling tirade. "You used to dance with her."

Tony clicked his tongue, nudging her into his arms with a jerk of his foot. "Dad was never much of a dancer. Seemed a waste."

Thinking about the living and the dead like this, Natasha thought, was a mistake. Now, the floodgates had opened; now, they'd have to recognize they'd been human, once, and their existence had been scary and brief. Now, they'd have to talk about it.

Tony took charge. He could inflame the thought aglow, somehow, instead of leaving it, untouched, numb and cold. His tone of voice was fond.

"We met first. You remember?"

Nat gave him a little mischievous smile, playing this part one last time. "Technically, Clint and I met first."

Tony made an unimpressed little grumble on the back of his throat. "It started with us."

Natasha smirked. "I didn't recommend you."

"I didn't trust you."

They looked at each other and it was so easy to mind-read right then. Truth and trust, stripped bare and raw. They were both smiling the same smile, somehow. There was nothing to hide anymore.

"Things change."

"They really do."

"Seems fitting that it's ending with us, too."

Natasha gasped. "Oh my God, Steve, is that you?" Tony kicked at her ankle. "Fate, indeed. Very poetic."

Tony rested his chin on her shoulder, and Natasha rested hers on his.

They both let out a shuddering sigh.

"Tony."

"Hmm?"

"If this was the last birthday party you were ever gonna have, what would you do?"

Against her cheek, Tony's stubble shifted until Natasha knew he was smiling. "I'd tell my daughter I love her. Kiss my wife, full-on make-out session. Watch really old movies with Peter. Return of the Jedi, probably. Punch Steve in the face and then hand him the drink Thor spiked for the kid; y'know, catch up. Demand Rhodes and Happy be the really inappropriate guests cracking jokes at my funeral. Script the jokes myself, 'cause they're hopeless. Thank the team." His hands tightened on her. "Dance with a friend. I'd do whatever I wanted to do, with whoever I wanted to do it with."

"No Iron Man?"

Tony glanced down at his phantom arc reactor. "Iron Man dies with me. I hope."

Natasha arched her eyebrows at him. "What does that mean?"

"I don't have to- there's nothing to build anymore," Tony explained slowly, dreamily. "No shield, no suit, no weapon. No home, no trust. No more armors. No more protection. They'll be okay. They'll all really be okay. I think I finally believe it now." His eyes refocused, bore a hole into her. "I wish I could've protected you too."

Natasha ignored that, and pressed herself against him further. "They'll miss us," she said, and she finally believed it too. The music grew louder again.

"They'd better."