Title: Join Me ~ FrostIron
Fandom: Marvel (movie 'verse)
Author: Batsutousai
Rating: T
Summary: Tony is dying from the very device that saved his life. He's just begun to accept his fate when an unexpected ally comes with an offer he's not sure he can refuse.
Disclaim Her: This story is based on characters and situations created and owned by Marvel. No money is being made and no copyright or trademark infringement is intended.

A/N: From a list of prompts on tumblr as a response to a prompt given to me by mystatusquo. The prompt was Join me, frostiron, please? :)
Entered in the Super Fun FrostIron Contest, for which voting starts on the 15th. *wink, wink, nudge nudge*

This takes place at the beginning of Iron Man 2, completely throwing canon out the window.
It's only FrostIron in the vaguest sense of the ship, I fear, but if you squint... (Sorry, mystatusquo. Though, given how long it took me to fill this... *shame* )

-0-

"I can save you," a voice offered as Tony checked his blood toxicity levels again.

The engineer jumped off of his stool and spun, looking for the culprit even as he reached for a metal rod. But the lab was empty, save for DUM-E whirring in the corner, making the mess he'd been ordered to clean up even worse.

"JARVIS?" Tony called, still scanning the room.

"Sir?" JARVIS replied, completely unconcerned.

"Your bodiless butler cannot sense me," the voice said, breath ghosting against Tony's ear.

Tony whirled and waved the rod in the space where the breath should have come from, but there was no resistance, no sense of the blow having connected. "What– Who are you?" he demanded, stumbling over his question.

"Sir?" JARVIS called again, and now there was concern in his automated voice; just human enough that Tony could convince himself he wasn't going to die alone.

Tony swallowed, eyes darting around the lab. "Jarv, run a scan. Energy and temperature anomalies."

A surprised laugh came from Tony's disembodied intruder as the 3D imaging system came online, outlining a human form in bright blue just beyond the reach of Tony's rod. "Clever," the voice said, approving, and the blue outline filled with a smartly-dressed man. Chin-length black hair, slicked back off his forehead; eyes a green so bright, there was no way they were natural; appearance somehow both younger than Tony, and decades older. He had almost half a foot on Tony, but the cut of his suit suggested Tony was the far more muscular of the two, even with the current degradation of his health.

The disappearing trick was disconcerting, but at least the man was human – or human-esque; the blue that had highlighted him suggested the intruder had a body temperature far below a human's – and that went a long way to soothing Tony's rattled nerves. "I'll ask again," he snapped, pointing his rod at the man, "who are you?"

The intruder tilted his head, completely unconcerned at Tony's threatening stance. "I answer to many names, Stark," he allowed. Then, before Tony could come up with a response to that, he said, "You're dying. I estimate you have no more than two months."

Tony swallowed against the sudden block in his throat; having a timeline was somehow so much worse than the silent ticking of the clock. "Right. Great. Thanks for that update." He tossed the rod in the general direction from whence it had come – ignoring the rattling sound it made as it clattered to the floor – and dropped back onto his stool, rubbing at his eyes.

The intruder took a step forward, as smooth as if he'd simply slid over the surface of the floor, head still tilted in that vaguely curious manner. "I can save you," he offered, voice void of inflection.

Tony laughed, low and bitter, and glanced up at the other man. "No one can save me, Potter, not even the Boy Who Lived."

The intruder blinked, his confusion clear for a moment before he smoothed it over. "No mortal science will save you," he agreed. "But I do not offer a solution born of mortality."

"What then, unicorn blood? You know that shit's cursed, right?"

"...you are a thoroughly inexplicable being."

Tony's responding laugh was lighter, almost delighted, and something like amusement glinted in the too-green eyes across from him. "Alright then, Harry. What's your magical solution?"

The other's right eyebrow went up at the name, but he ignored it to say, "I shall change the properties of your blood to accept that which is poisoning it."

Tony blinked.

"It is quite simple."

"Naturally," Tony murmured, staring at the other like he'd have made more sense talking about unicorn blood. "I assume it's also painless?"

The other put on what was, quite possibly, the most terrifying smile Tony had ever seen. "Naturally," he said, completely stealing Tony's line.

"If you tell a lie, does your nose start to grow?" Tony wondered a bit inanely.

The man rolled his eyes, his expression smoothing back out.

Tony watched him for a long moment, gathering himself. A cure. Tony had run out of options months ago, had resigned himself to a slow, painful death. All his tests, now, were for show; a way to tell the world that he wasn't a quitter, though he had long since ceased to care. Some days, staring down at the increasing percentage, Tony wondered if it wouldn't be kinder if he just took a quick step off his balcony, into the ocean so far below, he'd never survive. If he was drunk enough, Pepper and Rhodey would never question it, never wonder why he'd refused to say goodbye.

"What's the catch?" he rasped.

The other moved one shoulder in an elegant shrug. "The loss of your physical humanity. Your blood would be as poisonous to other humans as your metal heart is to you now. Perhaps other, minor changes to your physiology, as would be expected from changing something so imperative to your continued survival."

Tony thought he could live with that. A slightly hysterical laugh tickled the back of his throat at the unintentional pun, but he swallowed it back to ask, "What's your price?"

Nothing on this Earth was free; Tony had learned that lesson the hard way, trapped in a cave in a desert with a man who traded his empty future on the blind hope that Tony could make it something more.

The man smiled, sharp and approving. "A debt. Owed to me, one that will balance a life preserved, to be paid at some undetermined point in the future."

Tony considered that, weighed the unappealing prospect of being in another's debt against Pepper and Rhodey.

It wasn't a hard choice.

Tony stood and held out his hand. "You have an agreement."

The man practically purred as he accepted Tony's hand to shake. "So we do," he agreed, a green light haloing around him. The light travelled up Tony's arm from where their hands were connected, leaving a line of fire in its wake.

It felt like his blood was boiling, and Tony clenched his teeth together so hard his jaw ached to keep a scream bottled up. Green sparkled across his vision, and it sounded as though JARVIS was calling for him from a great distance.

Then, directly in his ear, a voice like silk and ice whispered, "Until the moment of collection, Stark."

-0-

When Tony woke, he was laying in his bed, naked as a new-born babe and sweating like a pig under the light sheet that was tangled around his waist and caught up in his legs. "Jarv?" he croaked, voice an absolute ruin. God, how much had he had to drink?

"Sir? Thank goodness," JARVIS said, voice laced with relief and too much stress for Tony to have simply drank too much the night before.

Tony forced himself to sit up, everything aching. "What the fuck happened?"

"You received a visitor," JARVIS explained. "You've been unconscious for nearly two days."

And, just like that, everything came rushing back: the man in his lab, an insistence that Tony could be saved, a bargain struck.

Tony choked back a noise that might have been a whimper and leaned over to grab for the small box he kept in his bedside drawer. "Check palladium levels," he whispered, pushing his thumb against the tiny needle.

"Blood toxicity, one hundred percent," JARVIS reported out loud while Tony stared helplessly down at the number on the tiny screen he held in his hands.

"Well," he said at last. "I don't feel dead."

"It's a miracle," JARVIS replied, deadpan.

Tony's mouth twitched with a smile and he looked down to pull out the arc reactor, checking the cartridge. Impossibly, it didn't need to be changed.

"Wait, two days? Pepper's going to kill me," he moaned, shoving the reactor back into his chest and trying to resist the smile threatening to break across his face.

He was alive.

..