Perhaps unsurprisingly, Steve had a remarkably high pain tolerance. Nearly two decades of getting beat up in back allies tends to do that to a guy. Getting kicked, punched, shoved to the ground - it had rarely fazed him, even when he had bruises rippling up and down his skinny arms. Even on the few occasions where Bucky hadn't been there to step in, and the injuries had been far more serious, he'd clenched his teeth and limped home, though he'd usually realized in the end that his arm or rib was broken, and he should probably get to a hospital after all.

But when he'd been injected with the serum, the pain came close to breaking him. He could feel every one of the cells in his body - feel them twisting and changing, feel them burning from the inside out. He was on fire; he was dying; he was dead and in Hell. The world vanished, thoughts vanished, until only the pain was left. He didn't realize he was screaming, until he felt it scalding his throat.

Through the haze, a single voice cut through: "Shut it down! Shut it down!"

Even in this state, he knew what that would mean: he'd go back to being pathetic, short, and unable to fight. After coming so close to actually being strong enough to help with the war, he couldn't stop now. He had to go through with it. And so, with every ounce of strength left inside him, he bit back the screaming and shouted something instead. He shouted that he could handle it, that he was okay; even though he wasn't.

It was the worst pain he'd gone through in his entire life, and he never thought he'd have to go through anything like it again. Unfortunately, life seldom turns out the way one expects it to: something that was especially true for an Avenger.

It started out as a normal enough encounter. They'd discovered the location of an abandoned Hydra base, and they were investigating it with the hope that they could find some sort of information that would lead them to Loki's scepter. In all likelihood, they knew, any data had been entirely cleared out by Hydra before they'd left, but it was their only lead at the moment, so they lost nothing by pursuing it. Once they arrived, the team split up to search the apparently empty grounds. Steve's voice filled the comms, telling everyone to look out for guards, and watch for any Enhanced. It was a typical warning, one he'd given a million times before, and Tony was about to make some kind of sarcastic comment before Steve's voice returned.

"I think there might be someone here-agh!" He cut off suddenly, the clear implication being that he'd been attacked.

"Everyone converge onto Steve's location," Natasha said. "Let's take the fight to them."

"Let me know if you need me," came Bruce's voice. He was still in the quinjet, waiting in case of a Code Green.

"Cap? What's it looking like?" Clint asked.

"I-" Steve started, and then cut off, the sound of labored breathing coming through instead.

"Captain?"

And that's when the screaming started.

Steve's voice, twisted almost (but not quite) beyond recognition with pain and volume, blared through the comms. The piercing, almost inhumanly loud cries were a verbal knife in the Avengers' ears.

"Jarvis, shut off Cap's microphone!" Tony shouted, eyes watering with pain. The assault on their ears stopped, but they could still hear the screams echoing off the base's walls. A single thought passed between the Avengers: Steve was in trouble, and it was very, very bad.

Forgetting security, forgetting the mission, the Avengers ran (or flew, in Tony's case) as fast as they could in the direction of the screams. If they'd had to describe what they expected, then blood and gore, guns, and monstrous freaks would probably have featured heavily in their minds. But nothing could have been farther from the truth.

The room was empty but for Steve, who was writhing on the floor, screams spilling from his lips, eyes wide in agony. An huge, thick - and empty - syringe lay on the ground beside him, in danger of being crushed as the soldier spasmed helplessly. None of them noticed it, but the door on the other side of the room was swinging slightly as if someone had just passed through. The shock of Steve's appearance was so incredible that not even Natasha, a super spy trained in recognizing minutiae, could take in anything else except the very obvious. Steve Rogers, their unbreakable leader, whom none of them had heard so much as complain about an injury, was screaming on the ground like a helpless child.

But there was another occurrence that was quickly becoming impossible to ignore. It was Natasha, the best among them at noticing every tiny detail, who saw it first.

"The serum is being reversed." She tried to state it unemotionally, as an analysis of the situation, but her voice betrayed the tiniest amount of the shock and worry that was raging inside her. Even as she said it the effects became clear to everyone. Steve was shrinking before their eyes. His muscles were receding; he was getting thinner every second. The change had been slow and hard to see at first, but like a train gathering momentum, it grew faster and faster, and his screams only got louder. He didn't even seem to know they were there.

After a few minutes (though it felt like a few hours), the screams faded into nothing. Steve stiffened for a moment, gasping, then went limp, his eyes rolling back into his head. The Avengers were left to stare at a shortened, skinny, break-him-with-a-touch version of the captain - impossibly different from the man they all knew. The spell of immobility that hung over them shattered like glass, and they all rushed over to surround their leader. Once they made sure that he was still breathing, Tony, still in his suit, carefully lifted the unconscious man and carried him back to the ship. Bruce was waiting for them - he'd heard the screams and Natasha's statement, but of course hadn't been able to see what had been going on. He drew in his breath sharply when he saw Steve.

"How?" He asked, shocked.

"Someone injected him with this." Clint appeared behind Tony, holding the syringe in a thickly-gloved hand. Trace amounts of a blue liquid could be seen round the edges of the glass. "Think you could figure out what was in it?"

"I can, but I'll need the lab."

Clint nodded, handing the syringe to Bruce, who grabbed it delicately in his shirt and took it to be stored for the journey back. Clint was about to say something else when they heard Natasha's voice on comms. She and Thor had stayed back to search the building.

"We've got eyes on the attacker."

"Where are you?" Tony asked. Almost immediately, a bolt of lightning crashed through the air, bursting through the ceiling of the base and pinpointing a spot. Tony was gone almost before the flash had ended. Clint watched him leave, but didn't follow. Someone needed to stay with Bruce and watch over Steve.

Ten minutes later, their teammates returned, dejected and angry. As soon as Cap's attacker had realized he couldn't escape from the three Avengers, he'd popped the cyanide pill in his teeth. He was dead before they could do anything.

"Typical Hydra," Bruce muttered.

Once they were all on board, Clint took off. Though Steve appeared to be stable, they needed to get him back to Avengers tower as soon as possible.

And then they could find a way to fix him. There had to be some way, after all.

Didn't there?

Hope you enjoyed the first chapter! A big thank you to BannerFanner for beta-ing. The title comes from a verse in the song "Surely Someday" by Adrisaurus. She's amazing and you should check her music out on YouTube!

Also, as a side note, this story won't be canon compliant with Age of Ultron. It should be with everything else though. I guess that makes it technically an AU?

Please review if you feel like it!