Title: One Life

Author: ELLE

Pairings/Warnings: Tony/Pepper, Tony/Bruce, explicit language, graphic depictions of death – although this is not a death fic despite all appearances, bad science, my usual heaping helping of angst, violence and gore, some timeline variance from MCU canon

Notes: The original idea for this fic was inspired by a work done in another fandom titled "Far too Young to Die" by Miss Murdered. I never read the whole thing, only the rough draft of the first chapter, but I immediately adored the concept and still remember it fondly over a year after initial exposure. Although I am sure that she will never read this note, it is important to me to acknowledge someone who had such a profound impact on me as a writer.

Also a special thanks to my lovely girlfriend for her encouragement, advice, and patience as I made my way through this beast.

I keep going to the river to pray
'Cause I need something that can wash out the pain
And at most I'm sleeping all these demons away
But your ghost, the ghost of you
It keeps me awake

Ghost – Ella Henderson

1: Prelude

Two mausoleums were constructed after Anthony Edward Stark's death. One was public, placed in what was colloquially known as Avengers' Square, a boastful monument of sculpted marble with the vengeful archangel Raguel guarding the door, wings spread and wielding a sword, like a testament to the life of the man inside, taken far too soon. Flowers were piled outside the door for weeks but then graffiti also marred the stone and was washed away again and again – the varied and heated opinions of the hero's character drawing out visitors from all over the city and beyond. Even those that couldn't make it still watched the billionaire known as Iron Man's last pilgrimage on this earth broadcast across every news network in the world as he was laid to rest inside.

The second mausoleum erected in his honor was private and a different man sat buried in it, only two sets of eyes ever falling upon it's existence. This mausoleum was only a hundred feet away, in the basement of Avengers' Tower. There were no flowers here, no homage, no acknowledgement, just the private death of another man, a man consumed completely by Tony's memory.

Bruce sat bathed in the soft glow of computer monitors, hunched over as he reviewed the analysis of the last few lines of changed code. Sitting there alone he failed to draw any parallel between the decomposing body of Tony Stark to his own starving and neglected form, both locked away in darkness. Failed to think about much of anything other than the project before him, displayed across three over-sized monitors, code he'd written and rewritten hundreds of times over the past three months surrounding him as effectively as the mahogany coffin entombing his friend.

Tony had always been the stronger programmer. If only Bruce hadn't let him die.

The quiet pad of feet across the floor alerted Bruce that someone else was in the room – but he hardly cared. Only one person ever came to visit him down here and that was Pepper. He wasn't really quite sure why. Well, it was technically her tower, he supposed, and he had taken up something of a permanent residence there. But still, he had expected Steve before Pepper, but according to her Tony's death and Bruce's subsequent disappearance had fractured the team. Steve went back to SHIELD HQ; Sam accepted some contract position. Natasha and Clint theoretically went their separate ways and disappeared again on a more permanent basis. Thor apparently still came to this world to help Steve, at least he still showed up on the news, but Bruce didn't have any concept of the frequency of those appearances – nor did he care. He had one singular focus since they placed Tony's body in that mausoleum and he did not stray from it.

He heard the soft disapproving hiss of breath as Pepper noted the food she'd left some hours ago that he hadn't touched. That wasn't always the case, sometimes he would eat enough to sustain himself a few more hours, but he was so close now that it didn't matter whether he ate or not. He hardly felt hunger anymore anyway.

But he could feel her hovering just outside the range of his personal space – nagging, like an insect he wouldn't be able to swat away. Knew she had brought him something else to eat as he caught her setting a new tray down in place of the old one, sliding it carefully into his reach. He didn't look over though, didn't reach for it. It didn't matter. This world was so temporary.

The silence was tense between them and it distracted his thought process. Bruce knew she had something she wanted to say, but just like always she couldn't just say it. He wasn't sure if that was a feature of her personality – surely not, she successfully ran a multibillion dollar corporation – or if he had morphed into some even more unapproachable monster than he had been in all the previous years of his life. It wasn't a thought he really wanted to contemplate the answer to, although he knew. Vaguely he wondered what he looked like. The fingers of one hand scratched absently at his beard. He hadn't worn a beard in... shit. Not since he taught briefly in Qatar. He guessed he didn't really want to know what he looked like.

"Yes?" he asked at last, knowing that if he didn't say anything Pepper would stand there indefinitely – or at least long enough to become ridiculous before she left without saying anything at all – and Tony wouldn't have wanted that. And he didn't dislike Pepper anyway – after all, he was doing this as much for her as he was himself. He was just so close now that he didn't really feel like wasting time with meaningless conversation either.

But Pepper didn't know that. She didn't understand. He had to be patient. Deep breath in, let all the anger out.

"How long are you going to do this to yourself?"

Bruce's fingers found the bridge of his nose as he sighed. This again. He'd thought he'd stopped this line of questioning weeks ago but apparently not. It was his own fault, he was too slow. If he had solved the issue with how to stabilize a quantum field earlier then they wouldn't even be having this conversation.

"I'm almost done," he replied, which was the truth. "Then I promise, none of this will have happened."

Pepper made a sound that was some mixture between a sigh, a whine, and a huff of indignance. It was so bizarre and so unlike her that Bruce actually turned to look at her for the first time in weeks just to make sure she was okay. It took his eyes a moment to adjust after staring at the screens in the dark for so long, but as they did his brows furrowed. It appeared that she had been crying.

"None of this is your fault," she nearly pleaded and Bruce felt confused by her sudden passion. They'd had this conversation several times since Tony's death, but she'd never been moved to tears before.

"Pepper –" he started, his patience for this conversation immediately non-existent. How was it that she didn't understand? He wasn't going to let Tony die such a meaningless death. Not Tony. Not again.

"He will just make the same decisions again," she quickly interrupted, as though she were some authority on Tony's decision making process. Maybe she could speak for him with regards to Stark Industries, but Bruce refused to believe Tony couldn't be persuaded to make a different decision, if only he'd had the chance. After all – she may have been his lover, but Bruce had been his best friend.

"You don't know that," he replied simply as he turned back to the monitors, unwilling to be drug down into this argument again.

"And if you kill yourself?" she asked, strain in her voice and Bruce paused.

He thought about the casket, the warm brown wood, the warped reflection of his face as he looked down on it, the way it felt slick under his fingers and the way tears pooled in little droplets on the lacquered surface before they slid down the curvature of the case. He thought about the way his knees buckled as he fell against it, wishing he could lay down beside him, or take his place – the way it should have been. How Steve had to physically carry him away because he couldn't force himself to stand, the weight of his guilt crushing him entirely. He thought about how the whole city mourned Tony's death and the way Pepper stood there and delivered a flawless eulogy, calm and serene, her eyes rimmed in red as she spoke to the future Tony would have wanted – the future he would never see.

"So what?" Bruce muttered with a glare shot back over his shoulder after the impatient click of Pepper's tongue.

"The world still needs you," she argued and he sighed, turning the chair to face her, his elbow on the table and his jaw resting on his knuckles, looking over his glasses at her in disbelief.

"The world doesn't need a monster like me," he replied, completely devoid of emotion.

"The Hulk –" she started, but that was it. The apathy he felt was quickly replaced by rage.

"I'm not talking about the Hulk!"

Barely contained anger snapped with every word and she took a step back, shocked into silence. Bruce recognized that kind of fear. What's going to happen now? Was he going to snap? "Hulk out?" Why did everyone always assume that the Hulk was the monster here? The Hulk was just a manifestation of the monster that was Bruce Banner.

He took a deep breath and unclenched his fists, feeling his heart rate drop. He was almost done. There was no use getting worked up now. He might not have been able to save his mother, but he could save Tony. He would save Tony.

No one else deserved to die because of him.

"I'm sorry," he apologized as he turned back to the computer screens, shielding her from himself.

His thinking was warped and he knew it but – everything he cared about was taken from him eventually. Of course his thinking was warped.

"Please – leave. I'm nearly done."

There was a long moment of silence between them. He could practically hear her hesitation. It made his skin crawl; the distance between them some physical thing. He didn't even know what she was doing down here. He didn't even know why she cared.

"When should I come back to... see?"

The hesitation, the unasked question, the sound of her swallowing hard around what she was asking was all right there, right on the surface. He chuckled. It was a little sad, a little sick.

"I don't really think that's going to be a concern," he muttered darkly. "I'm using the prototype two arc reactor as a power source. If this doesn't work, most of the east coast won't exist."

Bruce blocked out her gasp, her prickling anger. It was selfish, yes, that was how she would see it – her and her cold graphs and charts and dollar signs. There was a reason S.I. managed not to tank after Tony's death – she was a phenomenal statistician with an incredibly level-head. And he wanted to argue that, wanted to yell at her, make sure she understood that he was doing this for her, too. That she would never have to see her fiance die... but then. He didn't want to know what her response would be to that, either. Tony... Tony deserved the best of everything. Bruce needed to believe that she was the best thing.

And maybe she was. She surprised him and spared him the lecture, instead walking over to sit down on the table next to him, glancing over the monitors with a hint of disdain. The question she asked was one he wouldn't have expected – not from her.

"So you really believe this will work, then?"

He was buoyed by her confidence, her understanding that he wouldn't attempt this without that belief, her realization that he wouldn't be dissuaded.

"Absolutely," Bruce answered without hesitation, their eyes meeting for a moment. They were both sad, hers and his, both frustrated by the position they were in. And maybe – Bruce thought, hoped – maybe she understood that he was doing this for her, too.

"I don't know how you'll convince him," she sighed, rubbing at the base of her nose with one perfectly manicured hand, brushing away her bangs. "He cared so much about you – but that doesn't mean he'd listen..."

It felt like a punch to the gut to hear her say that and it took everything in him to maintain his limited composure. He ran a hand back through his hair, tried to steady the shaking in his fingers. If Tony had known it meant his own death, he wouldn't have come out with them. He cared about Pepper more. He wouldn't have left her. The rock on her left hand that she still wore was a testament to that. Bruce had to believe that.

He decided there was no good answer to that and he kept his mouth shut. It was inconsequential. Whatever he had to say to Tony, he would say. He would tell him he hated him if that was what it took, destroy their friendship so long as he would live – fine. Bruce could take it. He could take any outcome other than this.

"So what will happen?" she asked after she realized he wasn't going to respond. Her voice was tentative, hesitant, as though the conversation was a roach she stepped on and she knew it was going to be messy but she just had to lift her foot and look. "Isn't this one of those things you see in the movies? Won't you create, what is it, a time paradox trying to talk to yourself?"

The corner of Bruce's mouth tilted upward. There were times he understood what Tony saw in her – and this was one of them. Tony would've gotten off explaining specifics to a willing audience – Bruce, unfortunately, did not.

"There's a pretty damn good chance I'll kill myself," he confessed as he ran a hand down his tired face. "But if I don't, there shouldn't be two of me. I'm not going to say it's impossible because, well, I'm the living definition of 'freak accident.' But hopefully I'll just rejoin the old timeline with the knowledge I've acquired since his..."

Bruce could never bring himself to say it. He'd thought it a million times but to verbally acknowledge that Tony was dead...

"'Hopefully?' So if you don't remember building any of this – this thing?" she asked, gesturing across the entirety of the lab, taken over by a mass of lasers and cables and computers. "You'll just be doomed to repeat everything all over again – right?"

"Right." He met her stare without remorse. He would literally halt time, melt it down to a repetitious few months for all eternity if it meant he ever had the slightest chance of bringing Tony back.

Pepper sighed as she stood, the finality of Bruce's singular response effectively closing the conversation. But she paused and took one last look at him, a hint of pity or maybe, Bruce thought, some kind of empathy, of understanding flitted across her face and her mouth tightened for a moment, her fists too.

Her mouth opened but nothing came out and so she closed it again, swallowed, and started over. Bruce had rarely seen her so uncomposed.

"I know it won't make a difference for me," she began, slow and careful like each word was very important and so he listened closely. "But if I had the chance to do it again, I would make sure he understood how much I loved him."

Bruce swallowed hard, emotion he'd carefully kept buried for so long too close to the surface anymore. At least here was the proof he'd needed that Pepper was the best thing, that this would be worth it.

He didn't know what to say – worse, he didn't know that he'd be able to speak without his voice betraying him – but Pepper just smiled that tight little smile, gave him an awkward pat on the arm as she leaned over to grab his old, untouched tray, and left without saying anything else. And then, he was alone again.

Loneliness was nothing that Bruce ever thought would bother him as intimately as it did now. But he missed Tony's teasing voice correcting his mistakes and questioning his judgment, missed Tony making them break to eat and ordering whatever exotic food Bruce was craving, missed Tony's constant companionship in the now empty lab. He stared at the code in front of him and sighed. It was easy to imagine Tony hovering over his shoulder, hands pressing down on the back of his seat, chastising him for doubting his work.

But there was a lot more at stake here than a lab disaster or a couple months of wasted programming. Not for him but then he was so used to caring more about the effects of his actions on others than he was himself that still, he hesitated. Though only for a minute because truthfully he couldn't go on like this. If he couldn't fix this... then he was better off dead. This experience taught him nothing if not that he couldn't trust himself not to get involved with people again. And that every time he did, it only ended badly.

Without any fanfare he compiled the program one last time, instructing JARVIS to run it on his command, and he stood, body aching with neglect. Soon, though, it would all be over.

The lab was a mess. Bruce acknowledged that as he crossed the room to stand amongst the rubble surrounding the makeshift platform he'd created, lasers aimed downwards towards it, cables as thick as his forearms running straight to the arc reactor that had been intended to power the tower several rooms over.

For a moment he wondered how his friend would feel about such a bastardization of his tech, a cobbled together mess of machinery, nothing like the sleek design that always seemed to come so effortlessly to Tony. Even his prototypes were leagues beyond anything Bruce could've put together on a first try and he sighed. It was easy to hide the personal nature of this experiment behind the fact that he had taken such genius and talent from the world – but it was personal, even if he didn't really want to admit it.

Carefully he stepped up on the platform, stared at the lasers, took a deep breath. Whatever happened, either way, it would be for the best, he reminded himself as he tried to calm the nausea in his gut.

In a fit of nervous apprehension he found himself doing something he'd rarely done in the three months since Tony's death – he spoke to JARVIS.

"Do you think this will work?"

He hated the way his own voice sounded, thin and needy, betraying to himself how nervous and desperate he really was.

"It's difficult to determine an exact figure but the probability is quite low, sir," JARVIS replied, not helping the arrhythmic thump of Bruce's heart.

"Am I making a mistake?" he whispered, knowing it didn't matter but just wanting something, some support. It was pathetic how dependent he had become on Tony's companionship over the past year.

"I cannot say, Master Bruce," JARVIS replied, ever smooth and just a little insolent. "I only know of one person who would have been foolish enough take this chance."

Bruce blinked as his mind processed the statement, having never been called foolish by JARVIS before, at least not when compared to –

And then the realization hit him and he barked out a harsh laugh, warped and echoing weirdly in the lab, the first time he had laughed since Tony's death.

Tony would take the chance. Tony wouldn't hesitate.

The grin hadn't faded much as he took one less glance around the basement hole that had been his home for the past three months. Either way, this world was only temporary. This nightmare would be over soon.

"JARVIS?" he called out, strong and confident and seemingly utterly out of place in the tomb he had built from his sorrow. "Run the program."

"Certainly, sir," JARVIS replied as Bruce's grin widened.

The computer screens popped up voltage counters and Bruce closed his eyes to the telltale hum of energy filling the room as the lasers charged. It would only be a moment and then the pain of this reality would be gone. And the last thing he remembered, before he was erased from this existence, was a brief flash of light so bright he felt blinded beneath his eyelids.