A/N: This story is part of a larger series, and is specifically the sequel to One Step Left. It probably will not make much sense if you haven't read the rest of the series first.

"You could try irradiating me."

Bruce winced. "That could be a very bad idea."

"Anthony's wards were really obvious when they were going off."

"And if they don't go off, we've just fried you." Bruce set his mug of tea down – hard.

"Sorry," Steve said, holding up his hands and feeling guilty. Bruce had enough problems already. "But it would be proof."

And proof was what he really needed, because after a week of undergoing medical tests of every sort, including twice-daily meetings with Leo, even Steve was starting to doubt his own story. The serum had shown up as functioning at baseline normal levels; there was no trace of radiation damage or mutation to any of his cells; and since Anthony's arrival had blown out the security cameras in the lab before he'd appeared, there was no record of him, either. From SHIELD's point of view, Steve had had a break down in Tony's lab and then completely disappeared, only to turn up two weeks later insisting that the friend he'd found missing a head was actually alive. And also that there was an alternate version of him that was a sorcerer running around out there, and an Embassy where the gods of Earth congregated – like something out of a fairy tale.

It didn't help that Steve's story had a lot of holes. He couldn't talk about that other Dr. Banner – and he'd done a poor job of fudging a cover for it. He couldn't talk about the soul gem, either. It was another reality, but... something bigger than the Chitauri was coming. The soul gem might be a part of that war - and SHIELD was still leaking secrets like a sieve.

He needed to prove to SHIELD that those two weeks in another world had been real. More than that, he needed to know for himself that it wasn't just in his head.

He needed to know that Tony was really alive.

"We could try maybe radiating just a limb," Bruce said, sounding like he was regretting it even as he suggested it. "Minimize the tissue damage if it fails, and keep it away from your organs."

Steve had to clamp down hard to avoid letting too much eagerness into his voice – maybe Bruce would understand, but for anyone reviewing the tapes of this, it would just provide more evidence that he'd gone round the bend. "Try it."

"Tell medical to be on standby." Bruce was already standing, though, moving over to one of the machines that Steve was pretty sure had something to do with radiation, even if he had no idea what. When Steve didn't likewise move, Bruce glanced up. "I'm not joking about that. This is dangerous."

"The worst I'll get will be a burn," Steve pointed out. "I phone up medical, they're gonna run down here and tranq me."

"Yeah, because perfectly sane people shoot themselves up with radiation all the time," Bruce said wryly, giving him one of those assessing gazes that made Steve want to squirm uncomfortably. They'd both volunteered for the super soldier experiments, and Steve knew his own reasons and had known they were solid. Coming from anybody else, a look like that wouldn't have inspired self-doubt. But Bruce knew more than Steve did even now about the risks they'd both run, and sometimes Steve wondered if that wasn't something else altogether. He'd been trying to learn. He just had so many other things to catch up on – and an education in advanced and obscure science took a while, unless you were Tony Stark. Or Bruce Banner, for that matter.

But Bruce didn't say anything more when Steve still made no move to alert medical, so he supposed that in this, at least, they could agree.

"Do you need shielding for that?"

"No, or we wouldn't be doing this here," Bruce said patiently. "It's self-enclosed – and not meant for this level of output, so don't be surprised if it explodes. Stick your hand in here." Bruce's deadpan tone made it difficult to tell if he was joking... and after glancing at him, Steve still wasn't sure. Well, he was pretty sure that Bruce wouldn't blow up a teammate. Then again, he had just asked Bruce to irradiate him...

The brief memory of the other Bruce Banner – the Abomination – tried to climb to the forefront of his brain. Steve shoved it aside. He knew that Bruce was different, but his subconscious kept trying to make him think otherwise: the image of that fist closing about Tony was a sharp one, strong enough to outweigh its brevity. He hadn't yet managed to spend enough time in this Bruce's company to drive the misplaced caution away – one more thing to feel guilty about. Steve just hoped he was doing at least a good enough job covering to prevent anyone else from catching on, most of all Bruce himself... although his hesitation in sticking his hand into the device likely wasn't helping that.

Before the serum, Steve had been right-handed; ambidexterity aside, he still used his right more often than his left... a weakness in combat training. Not one that was gonna be resolved in a day, though; he stuck his left hand into the metal box, and then held it there while Bruce covered the gaps with a couple of weird, heavy blankets.

"Lead-lined," he answered Steve's questioning glance.

Steve choked down the urge to swallow. He needed to know this. He did. Not just – as proof. He needed it for himself. "We're not gonna be able to see the wards glowing," he objected.

"There's a spectrometer inside."

"They're magic wards," Steve said, his turn for deadpan.

Bruce glared at him, and for a moment Steve thought he'd pushed too hard and Bruce would call the whole thing off; then, in a huff, the scientist pulled one of the blankets – more like mats, really – away until a small hole was revealed, enough to let Steve see his own thumb. "Fine," said Bruce. "And when you go blind, it'll be your own fault." He walked over to the other side of the machine – it couldn't really be called a march, Bruce was too much the antithesis of military for that, but he definitely wasn't happy – and flicked a switch.

Nothing happened. Steve stared doubtfully at his thumb. "You're sure it's on?"

"No, I have no idea how to operate this three-hundred-thousand dollar piece of equipment, I just press buttons at random," Bruce said. That was more... Tony-ish than his usual snarking. He was really annoyed.

Well, he was owed it. No true debts between teammates or friends, but Steve needed to do something nice for him – although in the current situation, there was... not really all that much he could do. Maybe he could organize a team meal. Something. More than anything else, Bruce needed a distraction – except that currently he couldn't afford too many interruptions. And here was Steve, asking Bruce to spend time irradiating him.

"I'm increasing the level," Bruce said grudgingly. "Tell me when you see a glow."

When you see a glow. Steve felt himself stand straighter at that. When – Bruce believed him.

Seconds clicked by, and there was no sign of Anthony's wards firing up. He frowned. Maybe they didn't work for only localized exposure?

"If you were a normal person, you'd have a tumour in your hand in five years," muttered Bruce. "And probably one on your face."

"It's – not working."

"Imagine that." Bruce didn't sound sarcastic, though – just kinda disappointed. "That's enough, Steve." He flicked the switch again.

"I don't – we should try full-body."

"We really shouldn't," said Bruce dryly. He sighed. "And now we're stuck in here until the radiation protocols finish scrubbing the air. Come on, we need to decontaminate..."

"That," said Fury, glaring down at Steve, "was one dumb-ass idea, Captain."

"Retired," Steve noted, though he shifted uncomfortably in his chair. He thought he'd long since gotten over such instinctive reactions, but Fury had 'looming' down to an art.

"And you!" Fury turned on Bruce. "What the hell were you thinking?"

Bruce shrugged. "Better he ask me than somebody else?"

Fury considered this. "...acceptable," he concluded, and turned back to Steve. "You realize you can be committed to prevent you from doing harm to yourself, right? You are not invulnerable."

"I needed to know, Director." Steve ducked his head. "I guess now I do."

He didn't want to. He did not want to – there had to be something else; maybe, if they could try full-body radiation – there had to be something. Or Tony would show up. Because Tony was not dead.

"Not really," said Bruce, and they both looked at him. "I mean, uh. It could have just worn off. Unless you brought back a power source with you, or some sort of secondary effect to get more power for it, the human body doesn't naturally output enough energy on its own to provide the power that kind of thing would need."

"You think that there was a spell on him, but it ran out of batteries?" Fury summarized.

"Or it was taken off, or got disrupted. I'm not saying it did – the human body is made of mass, and mass is energy; sufficiently advanced tech could access it." He smiled, one of those half-smiles that Steve was pretty sure Bruce intended to be self-deprecating, but which just looked bitter. "Or it could be the sort of dimensional mass-energy-transfer that the Other Guy gets. There's a lot of ways it could be powered, even if we can't detect any of them. I'm just saying – it's not proof."

"So you're objecting to disbelieving in magic on scientific grounds, Dr. Banner?" asked Fury, but he sounded amused as he paced over to behind his desk and finally took a seat. Bruce remained standing – Fury's office was far from small, but it was still an office on the Helicarrier; Bruce would never be fully at home in his skin here. Fury had switched back into 'inoffensive' mode, though – as inoffensive as he got – and... that had been a test?

Steve knew it was when Fury pulled out a drawer in his desk and came up with one of SHIELD's anti-eavesdropping devices, turning it on and letting it blink blue.

Bruce tensed, and Steve shook his head at him – Fury was... well, Steve couldn't say that Fury wasn't that dishonourable, because some days he wasn't sure that there was anything Fury wouldn't do in pursuit of his goals. But those goals were generally honourable – and if Steve thought that was a contradiction in terms, he could respect it so long as Fury wasn't actually crossing lines. But more than that, Fury wasn't stupid. He wasn't about to do anything to them while they were here in this office.

No, he wanted something from them, and he was asking nicely.

"You believe me," Steve said, feeling his eyebrows shoot upward in surprise.

"Stranger things in heaven and earth," said Fury. "Though I'd be happy if you'd care to share the entirety of your tale one of these days, Captain."

Steve winced.

"Clap your hands," muttered Bruce, and louder, "That makes one of us."

There was a tiny pang of betrayal. Steve ignored it. He'd been through it all, and he was doubting it; he couldn't blame Bruce. But Bruce had been arguing in his favour a minute ago – sort of. "You don't?"

"I'm reserving judgement," Bruce demurred, but he did glance over, and whatever he saw in Steve's expression made him sigh. "Sorry. Look, Steve, I believe you saw what you say you did. But I know what you were pumped up with after Shenzhen. Grief and residual experimental painkillers can do weird things to the human brain." The slightly haunted look in his eyes hinted at a tale that Bruce had never spoken of – Steve had read about it in his file instead. Bruce had been captured by that asshole Ross – twice, although neither time had lasted long. One time, he'd surrendered willingly. "And you're talking about gods - actual gods, not advanced aliens. It's a bit hard to swallow."

"I hope you can keep that to yourself, Dr. Banner, because I've a favour to ask of you." Fury laid his hands flat against the desk. "I want you to take a second look at your results and change your mind. Say that you did pick up indications of some sort of anti-radiation shield about the Captain."

"Retired," said Steve.

"For now. I need you un-retired, Cap." Fury shook his head. "I need somebody who can run missions into infected territory. Shenzhen's a wash – the techs tell me that any data would have been wiped out by December Ninth – but there're plenty of other sites our scientists want to grab data from, places that aren't putting out more rads than Chernobyl. They need blood samples, tissue samples – mutation of the virus is a top concern." He looked at Bruce apologetically. "It's precision work, and for that, I need someone who isn't the Hulk."

"I'm not gonna be much good against a superzombie, sir," Steve said, wishing like hell that he had his shield. It was in lockup until the shrinks cleared him – leverage, because if they'd actually thought he was a danger, they wouldn't be letting him run about the Helicarrier. Especially not while it was flying.

"We've got all our people working on a solution to that. But we need somebody who can take point on trying out what they come up with."

Steve looked over at Bruce, who was staring down at the floor very determinedly, and then eyed Fury at distaste. Bruce didn't need to be here – Fury could have told him after – he didn't – it was effective manipulation, but it didn't leave Steve feeling very happy. He'd have agreed anyway – but, no, this was aimed at Bruce, wasn't it?

On December Ninth the Chinese had upped the ante from firestorming infected villages to nuclear war on their own people. To a degree, it had worked – or at least, the rates of infection in China had finally begun to slow – but dear God, the cost could not be worth it. Not that cost.

"Of course I'll help," Steve said, scrubbing at his pants and longing for his shield again, just to run his fingers along the edge of it and know it was there. "Uh. Contractor only."

If he wound up disagreeing with Fury about something, he'd need the extra leeway. The understanding of how to get it was something he owed Natasha for – it had been her who'd sat him down five months ago and explained what options he might consider with SHIELD, and all the legalese that had gone along with it. Apparently, most of her favourite aliases had law degrees. Had, before she'd been forced to burn nearly all of them.

"Thank you. Legal will have the paperwork waiting for you in your quarters."

"I haven't agreed," Bruce said wryly, and then gave another of those smiles when Fury tipped his head apologetically again – yeah, Fury was definitely playing with kid gloves today. "I'm not about to get up in your face about scientific ethics, Director. But there is, uh, sending a potentially... compromised... teammate out to get eaten by zombies."

"Dr. Banner, I'd like to send no one out to get eaten by zombies," Fury said. "If it's not Captain Rogers, it will be somebody else – who will have a much higher risk of falling to that fate. We've already lost four teams in exactly this manner. I appreciate what you've done for SHIELD – for the people of Earth," he cut off Bruce from amending that line himself. "But your alter-ego can't collect the data we need. And you, frankly, need the occasional break. You've been out there every day for the past two weeks. Let your team – your team leader – help you out."

"We're not much of a team anymore," Bruce said, almost a mumble.

Bruce shrank further into himself, and Steve winced. He hadn't seen much of Bruce over the last week – although he'd seen plenty of Natasha and Clint, who'd been assigned to keep an eye on him. Instead Bruce had been spending most of his time as the Hulk, chasing down superzombies – and on those rare occasions when they got assigned to babysit each other, Bruce in the lab and Steve with his sketchbook, he looked exhausted. Weary. As he did now. Guilt nagged at Steve again.

He looked at Fury's careful poker-face – not constructed to reveal no emotion, but to reveal only the emotion Fury wanted to convey. Steve was never going to be able to read him if he didn't want to be read – but he could try putting himself in Fury's place and working out the logic from there. Fury – SHIELD – needed a response team.

Thor was gone indefinitely. Tony wasn't back – yet. It had to be yet, and he would be back. In the meantime the War Machine was on temporary loan from the Air Force, with SHIELD fighting tooth and nail to get Rhodes permanently – and there had to be others out there. People with unusual skill-sets, abilities that could be put together to become more than the sum of their parts.

The idea behind the Avengers was a small response team with disproportionate ability to respond. But there was no reason they couldn't have a larger backup roster, ready to swap in and out as needed.

"Maybe we're not," Steve said, and he met Fury's gaze with his own: challenge accepted. "But we will be."