A/N: This story is for jamiehernandez8888! Thanks for the request!

Twenty-one months and counting since the dead had first started to walk the earth. Twenty-one months where Bruce had seen six of his friends move in with him, four of them get turned, and one of them nearly go crazy. Twenty-one months where Bruce had been bitten nineteen times.

He had found a safe house, a place where those of them who were healthy could hole up between supply runs. Those who were dead (not dead Tony insisted, infected, just infected) had a place too, a barrier of rubble that had been dragged into place to keep them from wandering off. Natasha would stay up on the roof and stare at them often. Too often, in Tony's opinion.

"What good does it do?" he muttered to himself.

Bruce shrugged. His latest bite hurt whenever he lifted his arm, but not nearly as much as seeing Pepper's red hair in the corral did. "It's comfort, I guess."

"It'll be more comforting when we find a cure."

Bruce hummed non-committedly. A cure had seemed so possible back then, back when Clint and Steve and Thor had all still been sitting around their table. Back when Pepper was still bringing Tony cups of scavenged coffee, and Bruce was only haunted by Betty's face instead of half of his friend's.

"One day we'll find it," Tony promised. "We'll be the saviours of the human race and everyone will have their families back together and no one will be alone anymore." He ran a hand through his hair.

Even if they found a cure, Bruce wasn't holding out hope. How many people had already been killed, would be killed before they found a cure? The only reason Tony thought a cure was possible was because of Bruce's ability to survive, and if it was up to him, Bruce wouldn't put a whole lot of trust in that. It had been a fluke that he had even survived the initial bite let alone any others.

"Tony," he said after a moment, "if this doesn't work – "

"It will work," Tony cut him off. "It has to."

Bruce sighed. Tony's need to protect the world, protect them had spiraled out of control. "It's not only your responsibility."

There was no sound from Tony's side of the lab for a long moment, and Bruce carefully did not look over his shoulder. Privacy wasn't something they were granted much of in this world anymore.

"You have a point," Tony muttered finally. "Why bother, right?"

"Tony," Bruce started, turning around, but the engineer held up a hand to stop him.

"No, you're right." Tony opened a drawer in his desk and pulled out a flask filled with whatever alcohol he had managed to scrounge. "I need to lay off a bit. Give myself a break." His voice cracked on the last word and he stormed out of the lab.

Bruce watched him turn right as he left. Right was the direction to the stairs and the stairs were how to get to the roof. And the roof… Bruce forced himself to stop thinking about it.

Bruce waited as long as he could stand, organizing and re-organizing the various lab equipment. It had been salvaged and scrounged from wherever they could find it, sort of like their little ragtag band. Unlike the glass beakers and bottles, his friends had shattered over and over again, and Bruce had no way of putting them back together.

He sighed, adjusting his test tubes in the rack that didn't quite fit them one last time, and then headed outside in the same direction as Tony.

There was only one way to the roof, and Bruce took it, not entirely sure what he was doing. Tony didn't need his comfort, just his help in finding a cure. If a cure was even possible… Bruce had been bitten time after time, but there was no one else like him.

No one else could survive being bit one time, let alone nineteen. Bruce wondered what it would be like to be left alone to wander the world by himself: watching the sun set over an empty world, the only noise being his heartbeat and the howling of the wind through abandoned buildings, his only company the shambling dead. No. That couldn't happen. He wouldn't let it be the end of the story – their story.

Making his way up the narrow stairs, Bruce opened the roof door. The sun was on its way to setting, casting long shadows over the cityscape. Tony sat on the edge of the roof watching the others wander around their makeshift corral.

"Hey," Bruce said softly, sitting down beside Tony, careful to keep a few feet between them so the engineer didn't feel as if he was being crowded.

Tony sighed. "Hi," he said hoarsely. Below him, Clint moaned as he shuffled towards a block of what used to be a side street.

Bruce kicked one foot against the building. "I'm sorry." He didn't elaborate on what he was apologizing for; there were too many things piled between them.

Tony exhaled harshly. "It's not your fault," he said. "Your immunity is – "

"Random." Bruce finished for him. Maybe it was his work with gamma rays, and maybe it was a random genetic mutation that nobody shared but him, but either way it was a cruel reminder of an utterly uncaring universe.

"Yup." Tony cracked a pained grin. "Either way here we are at the end of all things."

Bruce made a sound that might have been a laugh in another world. "That wasn't the end of the story, you know."

"Yeah, I know. But for us," Tony stared at Pepper's unseeing face below him, "it might as well be."

"At least we're here together," Bruce said. "I – I don't think I could stand it if I was the only one."

The sun had slipped further below the buildings and when Tony turned to look at him, the shadows made his face look ghoulish. "Someday you might be."

Bruce ran his hands over his face. "Don't remind me." He looked at Tony through his fingers. "Aren't we supposed to develop a cure? Heal the world?" His questions had an air of desperation around them. Please tell me we can do all this. I need to believe.

Tony sighed again. "You exist. That tells me there's… something out there. Some reason to keep going. For Pepper. For Steve, and Natasha, and everyone else."

Bruce shuffled closer to Tony. "I'm sorry," he said again. "For assuming your cure won't work."

"No, it's fine. I need to think of alternatives." Tony chuckled raggedly. "Just in case, you know."

"Well, until then," Bruce said, "here we are together, at the end of all things."

He was never quite sure who moved first, but both of them had the idea. Bruce's mouth met Tony's, both of them kissing like they were asking for help, for reassurance, for something to hold onto. Tony's tongue slid along the edge of Bruce's lip, and Bruce could feel himself getting hard. It was nothing, just a kiss, nothing that would have even meant anything in the old world. But that was then, and this was now, and now just a kiss was enough to get him going. Bruce pressed in, nibbling the edge of Tony's lip.

Tony pulled away first. "Sorry," he muttered, "sorry, didn't think." He looked at Bruce with too-bright eyes. "Pep wouldn't – she would – " He broke off with a shaky breath.

It was a symptom of the world they lived in that Bruce didn't immediately answer him. "Yeah," he said finally. "I get it."

Tony nodded, and then motioned to the roof door. "We should go in before it gets dark."

"Yeah," Bruce said again. The light was almost gone and the deep blue of twilight coloured the shadows. He followed Tony back down the narrow stairs and turned left instead of right, going back to his room instead of the lab.

Tony went right.

Bruce thought of him once he was safely in his room, of the look in his eyes just before they had kissed, of the feel of his lips and the heat of his mouth. It wasn't fair. Tony had a wife, Bruce had been engaged, and neither of them were gay. He should walk away. He should remember their cure. He should leave his personal thoughts at the door.

None of the "should's" kept him from calling Tony's name in the shower that night.

Neither of them talked about the kiss when Tony had to take his blood for another experiment the next day. Bruce held out his arm and Tony wrapped the length of rubber around his bicep as usual, then prepped the needle like he'd had years of practice instead of the months they'd actually been working together. Bruce supposed when you were drawing someone's blood every other week it would become second nature.

"Make a fist," Tony said, jolting Bruce out of his thoughts. "Thanks."

They sat in silence for a moment as Tony inserted the needle into Bruce's arm and started the blood draw. Bruce supposed there was nothing to say and was gong to ask about their plan for the vial when Tony broke the silence.

"I'm not gay."

"What?" Bruce asked after a moment.

"I – I'm not," Tony said, looking almost surprised at himself. "I've been into women, lots of them, but, uh, not guys."

Bruce nodded. "I'm not either?"

"That sounded like a question."

"No! Not a question, just…why are we talking about this?"

Tony slid the needle out of Bruce's arm. "Well, when two straight guys kiss on a roof at sunset, there are certain things that may be assumed, y'know?"

Bruce nodded in agreement. "Okay, but I'm not into you like that." He took a breath. "I think I just needed – "

"Human connection," Tony finished the sentence for him, pressing a cotton ball to Bruce's arm. "Yeah." He stepped back and started labelling the vial. "Okay, big guy, you're done."

"That's it?" Bruce asked, getting out his chair and grabbing one of their carefully rationed granola bars.

"Well, what else is there to say?" Tony asked, raising an eyebrow.

Bruce conceded and headed over to his own lab bench. "What are we looking at today?"

"I think I may have discovered something last night," Tony starts.

They worked all day, and it was the most in-sync Bruce had felt in a long while. At the end of the day, they shared a family-sized can of split-pea soup and commiserated over their work.

"If this pans out," Tony finally said, "we could maybe find something in the next four or five months!"

Bruce hummed, not looking Tony in the eye. Hope was too dangerous to let off a leash like that. Still, it was better than nothing, so he smiled and allowed himself to wonder what it would be like to have a deadline to aim for.

They shared a bed that night, and almost every night afterwards. There was nothing more to it, but it helped to have another body in the bed, to feel not quite as alone.

They worked side by side for the next four months. There was next to no need to go outside, so most days Tony spent entirely in the lab. Bruce volunteered for both supply runs and came back with one more bite after the second one. Tony cleaned the wound.

"Are you okay?"

Bruce shrugged. "Why wouldn't I be?" He didn't mention the feel of the woman's head under his fist or the noise her skull had made when he'd thrown the rock. "You know I can't be turned."

Tony nodded and finished wrapping a bandage around Bruce's arm. "It's not your fault," he said simply, before instructing Bruce on where to put the supplies.

That night in bed, Tony ran a hand through Bruce's hair. "Don't freak out," he said, when Bruce jumped a little. "Pep used to do this for me if I'd ever had a bad day or didn't feel well. I – well, I figured you needed it."

Bruce swallowed the lump in his throat and nodded. "Thanks."

Nothing else was said that night, but Tony stroked Bruce's hair until he fell asleep.

"Bruce! Bruce!" Tony burst through the door onto the roof where Bruce was standing, trying to catch a few rays of morning sun. "Bruce!" he shouted again. "I've got it, I've got it for real, we did it!"

"Did it, how?" Bruce asked cautiously. It felt too good to be true, all their long months of work and struggle coming together into something good now.

Tony grabbed his shoulders. "We have a cure," he said, not breaking eye contact. "We just need to test it on one of them and see for sure."

"Okay," Bruce said, forcing himself not to feel all the implications of the news. "Who do you want me to grab?"

"Pepper," Tony said immediately.

Bruce was already on his way down the stairs.

Outside in the corral was awful. It wasn't the smell – they didn't really smell that bad, all things considered – but the blank unseeing eyes and moans were too unsettling for words. Bruce looked around for Pepper and finally saw her standing in the corner.

"Come on, Ms. Potts," he said as he made his way through the pen. It was uncharacteristically formal, but it was the only thing he could think to do to stop himself from screaming.

He caught Pepper by the arm and started navigating towards the door. She moaned louder, and Bruce could see other heads turning towards them. He might be invulnerable to bites, but Bruce knew there was no way he could survive an angry Thor or Steve on his best day. There was only one way to stop the sound, so Bruce winced before covering Pepper's mouth with the bag Tony had given him.

"Sorry, sorry," he muttered automatically as he made his way out of the pen. Pepper was still moaning, but quieter since she could no longer see the The thought made him cringe, and he quickly slammed the gate and shoved her towards the door with both hands on her arms.

"Tony," he shouted as loud as he dared, "where do you want her?"

"Just bring her here and hold her," Tony instructed, standing in the doorway.

Bruce did, stopping far enough away from Tony that she couldn't grab him. "Okay," he said, "I'll hold her mouth while you inject her." He resisted adding a comment about Tony's idea of lab safety as he again put his hand over Pepper's mouth.

The injection went as smoothly as possible under the circumstances, and Tony stepped away. "Okay, let's see how that goes," he said, breathing hard. "It should take effect in the next day or so."

"The next when?" Bruce asked incredulously.

"It's fine!" Tony snapped. "I have a room set up next to the lab!"

"And how are we going to get her there?" Bruce asked.

"Very carefully."

They were able to manage it together. Bruce covered her mouth while Tony tied her wrists together behind her so they could navigate her down the hallway without grabbing either of them.

"You know, the last time we did this, it was a lot kinkier," Tony said. His pale face gave away the fact that it was the joke was the same thing Bruce had been doing in the corral – the only way to keep himself from screaming in terror at the thing they were trying to accomplish.

Slowly, they made their way down the hall towards Tony's lab. Pepper's shuffling footsteps echoed off the walls and her muffled moans made the hair rise on the back of Bruce and Tony's necks.

"Where's the room?" Bruce asked, every muscle in his body on high alert.

"Right there, on the left," Tony answered.

They maneuvered towards the door and pushed Pepper in as Tony grabbed the door and swung it shut. Just before it slammed and locked her in, Bruce sliced the ropes to set her hands free. She flailed at him, scratching one of his wrists.

"Get out of there!" Tony shouted, grabbing him by the shoulder and pulling him back.

Bruce slammed against the opposite wall while Pepper snarled at him through the closed door. She was energized now, hunting for the blood she had scented.

"What the hell were you thinking!?"

"She shouldn't be all tied up when your cure works," Bruce said rationally, holding his wrist to stem the blood seeping from the scratch.

"We don't even know if it'll work!"

"We do know I can't be infected!"

"I don't want you risking your life for me!"

The confession echoed in the small space. Bruce stared at Tony. The engineer's dark eyes stood out like hollows in his pale face. "You need to sleep," Bruce said.

"It's true," Tony muttered. "I don't want another person to die on my behalf." He crossed his arms as he stood, trying to disguise how much his hands were shaking. "I don't deserve it."

Bruce stood too, not sure how to approach. The intimacy of their friendship was reserved for the night, for their bed. "You know I can't be infected," he said again, an awkward offering of the only reassurance he could give.

Tony stared at him, dark eyes piercing through to Bruce's heart. "What about blood loss? Head injuries? Internal bleeding?" He pointed at the metal door where Pepper's wails were starting to lessen. "There are a hundred ways you could die to one of them without being bitten."

Bruce shrugged, suddenly frustrated. "You didn't seem to care when you sent me into the corral. Or when I went on supply runs."

"It didn't seem real yet!" Tony shouted. "I didn't think my godforsaken cure would be viable long enough to get it into one of them, I didn't think you'd be brave enough to wrangle one of them, and I didn't think we'd be able to get whoever it was down here! And then, now that all of that did happen, I'm not about to lose you to a goddamn freak accident!"

Once, on a rooftop at sunset, fearing no cure was possible, they had kissed. It had been fearful and horror-filled, staving off the inevitable with human connection the only way possible. Now, standing in a hallway in front of what would be either mankind's deliverance or destruction, Bruce kissed Tony. It was thank you, it was I didn't know you cared, it was I care about you.

Tony kissed him back with ferocity. Backing him up against the wall, he pressed himself against Bruce. Bruce gripped his too-thin shoulder blades and pulled the engineer close. Teeth grazed lips and tongues slid against each other, asking all the unanswered questions. Tony was shaking and Bruce slid an arm around his waist, pulling him closer, giving him permission to feel all of his rage and fear and grief.

They stayed that way for a long time. Eventually, they found themselves sitting on the floor again with Tony's head on Bruce's shoulder. "I love you," he whispered.

"I love you too," Bruce whispered back.

Tony laughed. "Well now what am I supposed to tell Peps?"

"Tell her I was the only guy left at the end of the world?" Bruce suggested. Tony looked at him with a flat stare and Bruce met it for as long as he could before they both broke down in laughter.

"No, but seriously, what do I tell her?"

"I think she'll understand," Bruce reassured him. "Besides, you didn't completely cheat on her."

"Maybe emotionally?" Tony paused to consider. "Is it emotional cheating if one of you is a literal zombie?"

"Tony," Bruce interrupted his musing, "it's Pepper. You love her. She loves you. You guys will figure it out." He stood up, offering a hand to Tony. "Now, come on. We need to eat something and sleep, otherwise you'll pass out when this thing works."

"I'll probably pass out anyway," Tony grumbled, following Bruce to the stairs. "Do you know what it feels like to save all of humanity?"

Bruce watched as Tony finished eating. "Come on. You need to sleep."

"I need to be there for Pepper."

"How long did you say this cure would take? A day or so? You have at least one night's worth of sleep before you get there." Bruce stared at Tony. "It's not all on you, you know. You can have a night off." Tony started to protest, but Bruce cut him off. "If your job is to be the savior of the human race, it's my job to make sure you survive to get there."

He herded Tony towards the bed. "Do you want the outside or the inside?" he asked.

Bruce woke up to an empty bed. He headed downstairs to the lab to find Tony staring at the door to the room. It was silent.

"It might have worked," Tony muttered when he heard Bruce's footsteps. "Or she's – " He never finished the sentence.

"Do you want me to go and check?" Bruce asked. There wasn't much he could do to relieve Tony's burden, but he could offer to carry it alongside him.

"Please," Tony muttered.

Bruce approached the door. Inside there was either going to be Pepper Potts, former CEO, Tony's wife, one of the smartest women Bruce had ever met…or none of that. He put a hand on the door handle and turned it cautiously, angling his body to shield Tony if a zombie attacked.

"Ms. Potts?" he started. Tony scoffed behind him. "Pepper?" he amended the statement.

There was a moan from inside the room.

Bruce's heart plummeted and he couldn't breathe. He hadn't known how much he was relying on Tony's cure, how much hope he still had left, until he heard that moan. He choked on empty air, trying to say something, anything, to tell Tony what he heard. There's no more hope. It is just us. He pushed the door further open, feeling as if he wasn't even in his own body. Distantly, no longer a participant in his body's actions, he looked down at the woman lying on the floor.

"Pepper?" Tony asked from out in the hall. "Pep?"

Pepper stirred, breathing harshly. A tear dropped onto Bruce's hand, although he couldn't remember when he had started to cry.

"Give her this." Tony rolled a bottle of water towards him.

Bruce watched it bump his shoe. A no longer disposable plastic water bottle filled with water that had been collected and run through the purifier the two of them had rigged up. He picked it up and took a step forward into the room.

He was breathing, he had to be, because that was the only way he could have lost his breath again when Pepper's hand reached out. She pulled herself up to a sitting position, head hanging down. Bruce reached down and rolled her the water bottle. Pepper looked up.

Her eyes were green, but that meant nothing. Bruce dragged in a painful breath. "Hey," he rasped.

"Hey." It was quiet, barely more than a rough whisper, but it was enough to knock Bruce back into his own body.

He turned around, flinging the door wide open. "Tony, you did it!"