Tony sauntered into the debriefing a half-hour late (what? It was his building, he could be late if he wanted). They'd started without him – well, none of them were idiots – and his entrance interrupted Steve – when did this Steve earn a first name? The helpful portion of his brain that noticed things like shawarma shops mid-fight informed him that it was about the time that he tossed his credit card at the aforementioned shawarma people; Steve had looked adorably sleepy, and alarmingly vulnerable, and Tony had run out of the restaurant without bothering to get his card back.

(We won, he'd said, when Tony had woken up, back in his home universe. We won, and oh, god, he'd been smiling, faint and true.)

"So, whose idea was it to nuke Manhattan? JARVIS, cancel that credit card I left at the shawarma shop and make sure they get paid. Because I gotta say, I didn't think SHIELD had nuclear capabilities – do you keep that completely off-grid, or did JARVIS fall asleep at the wheel? I wonder how interested the Joint Chiefs would be in hearing about it."

Not-Skirt-Steve looked mildly annoyed at the interruption, but by the time Tony had finished his first sentence, he could tell he'd won the good Captain over – in the current matter, at least. Whoever had been tasked with getting him up to date had done a shitty job with pop culture, but they apparently had given him the rundown on nuclear warfare. Huh. Steve was fixing Fury with that same icy stare that he used when he dumped the Hydra weapon down on the table back in the Helicarrier (and Tony could attest to just how damn icy that stare really was, even if the other Steve's probably would have been better – but he had the benefit of years of experience), and both Clint and Natasha were sitting up straighter, looking coolly interested. Thor just looked slightly confused, and Bruce leaned toward him, murmuring explanations. Tony kept an eye on the pair without ever glancing in their direction.

"Stark," Fury began, while in the background JARVIS noted, sounding affronted, "As per standard protocol, I cancelled that card the moment you came home without it, sir. I will ensure that the last transactions are honoured."

Fury ignored the by-play, speaking over top of JARVIS, even though Tony made a face at him in irritation. "The World Security Council holds the authority to – "

"Bullshit. You have nuclear weapons in American airspace, in American waters, under the direct control of somebody other than the American president – you really want to try to tell me nobody's gonna flip a lid over that one, let alone the part where you nearly nuked Manhattan?"

"It wasn't my decision, Stark."

"Pentagon it is," Tony fired back. "JARVIS, who do we have on speed-dial?"

Fury snorted, unimpressed as always. "You really want to compare arsenals, Stark? How's the latest round with Stern going?"

Senator Stern was a pain in the ass. A persistent pain – though Tony could cheerfully admit that he'd goaded the man enough to justify it. It was, perhaps, a personal – he wouldn't call it a failing. A personal quirk. That was one nice thing about being rich; you were supposed to be eccentric. Another nice thing was having lots of lawyers, who were for now keeping things tied up enough that Fury only had half a point. Between a military division like SHIELD having weapons, and a private – and 'eccentric' – individual having weapons, he knew how it would go down. On the other hand –

"Nuclear missile. On Manhattan. Our own fucking people, Fury," Tony bit out, his rising anger making his diction sharp. "I will take this to the Joint Chiefs, to the senate, to the goddamned president of the US, and Russia, and every other world power out there, and tell them exactly what firepower is in the hands of your trigger-happy defence force. I will destroy every last bit of tech I've ever built, I will fucking turn it over to goddamned Stern before I let your threats stop me, I swear to God." That wasn't a lie. The most important tech he had now was still just schematics in his head.

"I'm glad to hear that," Fury said mildly – mildly! "I'm sure the WSC will take that into consideration."

Off-balance, Tony reeled back, anger forgotten and irritation growing as he realized Fury's angle – and damn it, he hated being played like that. It didn't mean any of it wasn't true – he'd be quite happy to say it to the WSC's faces, if they even had faces, and hadn't had them surgically removed as part of the requirement of joining such a Omniscient Council of Vagueness – but, still! Managing! He hated being managed! Except by Pepper, but that had advantages that he really didn't want to think about in relation to Fury.

"Right," he said eventually, unable to come up with a suitable reply. He didn't trust Fury or the WSC to follow through – though Fury might want to, Tony had to grudgingly concede. He needed to get on the Helicarrier again, figure out where those isolated systems were and thread JARVIS into them. Maybe Fury would turn a blind eye – hah – this time. It didn't matter; JARVIS could be much sneakier when he wasn't in a hurry. For now it was moot, so Tony walked over to snag an open chair and drop into it, aware he was sulking and not bothering to hide it.

This entire meeting was a waste of time; he might as well get some enjoyment out of it.

"Captain Rogers," Fury turned his one-eyed stare back to the Captain, who was looking mildly impressed at the way Fury had handled Tony – Tony sunk further down in his chair and sulked harder – "If you'd like to continue?"

Steve barely took a moment to pause for thought before he returned right back into his narrative, highlighting tactics – especially the enemy's – pointing out weak spots, and carefully not saying anything about team-member interactions, even though that was arguably the most important aspect of all of this. Tony listened with one ear, eventually abandoning the sulking when it was clear nobody was paying attention to him and pulling up the schematics he'd been working on last night instead. He'd prefer holographic schematics to keeping it on a tablet, but not when Fury was sitting right there – yes, SHIELD hacked him just as often as he hacked them, but he liked to keep what secrets he could. Besides, he had... plans... for his future cyber-security.

It was entirely probable that Fury had a camera instead of an eye. Finding out that Fury was more of a cyborg than Tony himself was would not be a surprise. Idly, Tony popped up a new schematic and started detailing a camera-eye, pulling up the latest Oscorp biogen research and wondering many patents he could get away with ignoring. Norman was a dick. He sent an inquiring memo to Pepper, then stashed the new project on his private server, probably to be forgotten with most of his other random bursts of inspiration.

The bifrost-derivative was far more important. If only he hadn't lost all of the data that JARVIS had collected in Asgard... but that hurt too much to dwell on. Work was what he needed, not regrets.

He flicked through the models and projections he'd gotten from Foster's computers: the product of this morning's hacking, and the reason he'd been late – she'd had better security that he'd expected, not just the standard SHIELD fare. It was SHIELDware 2.0, the upgraded version, which meant it had taken him a whole extra fifteen minutes to crack. He frowned as he read – her ideas were good, but everything on her computer was too polished. She had to have somewhere to save her rough work, and since he'd hacked everything that she could possibly have touched, it had to be offline.

Tony just hoped she didn't keep it all in her head. That would be... hard to get at.

The Captain wound up to a conclusion, explaining, "When the portal began to go unstable they all shut down at once – it triggered some sort of kill-switch that I think we could – "

"Actually, that was when the mothership blew up," Tony interrupted absently. He scrolled through equations that presented a more accurate picture of Foster's bifrost repair-pulse-device (good god, could the woman not come up with a better name for it than that?) than any diagram in real-space ever could; variables danced in his head, and he started typing, his eyes half-lidded as he cast his mind back through weeks spent in the dark, staring at the runes and circuitry within the bifrost's nine-layered walls. He'd recorded much of what he could recall already, but – there had been a lot. And he'd had a lot to do.

Before the invasion, he would've had to go through his notes after to make sure he didn't have any outright mistakes: when he got to the end of a three or four – and once, but it was a bad week, okay? five – day engineering spree, with no sleep and only coffee and hallucinations keeping him up, he did, maybe, occasionally make mistakes in his math. And this was day four. But since Asgard, that... apparently wasn't so much of an issue anymore. Mostly. Good thing, too – even without being connected to the suit, his personal arc reactor had been fried by the return trip as well. If the other Loki hadn't removed the shrapnel, he'd have joined JARVIS in death shortly thereafter.

He was going to have to conduct some experiments on that – but those were going to have to wait for a time when he didn't have to be around people, especially trained spies who saw far too much.

"The mothership?" Steve said in surprise, and ooh, all eyes were on Tony again. His own thoughts bounced away and he let them go, feeling at once grateful and ashamed of it.

"Yup. Some type of control switch, I guess – apparently our alien friends can function in space, by the way, there was no sign of any shielding or protective suits. Thor, can you live in space?" Tony asked curiously, and Thor tilted his head to one side slightly, considering it.

"I would not have thought it possible, but after Loki – fell from the Bifrost," there was a slight hesitation there that made Tony wonder what word Thor really meant, "he managed to survive the journey through worlds, though I do not think he was... unchanged by it."

The void between worlds... it took all of his self-control to not shudder. But that hadn't been the space he'd meant. Perhaps Thor – this Thor, this tiny bit of Thor – really didn't know the difference.

"Why didn't the ship itself come through first?" Fury asked, looking Not Pleased to be hearing about it two days after the fact. Not that they'd been expected to do anything but recover for the first day – no one else knew that he'd had a head start on that.

Tony shrugged. "Too big? Too vulnerable? If the drones were linked to it then it would be the obvious point of attack, and I don't think it had anything like the shield on the Tesseract. Armor, maybe, but not enough to withstand your nuke – "

"What happened to your sensor readings?" Fury demanded.

"Arc reactor died when I went through the portal, reserve power was already drained – nothing left to power the sensors," Tony returned flippantly enough. He wished – but wishing would do nothing. If he was wishing that things had gone differently, he'd have spared the energy to wish that JARVIS had survived, first.

Steve – the other Steve, the nicer Steve – would have known what to say to make him feel better, to snap him out of this miserable funk. Without him – Tony missed him. Rogers was poor compensation. His eyes hurt and he rubbed at them, aborting the movement far too late to avoid giving anything away. Instead, he covered by asking, "JARVIS, get some coffee in here, will you?"

"Certainly, sir."

"Your best estimate, then," Fury said, again speaking right on top of JARVIS, and something in Tony's chest – all the light going dark – snapped.

He was on his feet before he realized it. The equations scattered like mist at his movement, suddenly made meaningless, with no more weight than the light that represented them. Ephemeral. Was that how Fury saw JARVIS? The version of JARVIS that had been in the suit – he'd left nothing behind when he'd died, overloaded and ripped apart along with the suit's computers when Tony had been grabbed off the bridge and sent hurtling back to Earth. One of his kids, dead, leaving behind a twin who had never even met his sibling. It hurt. And Fury, Fury didn't give a shit. Tony had had it with SHIELD reprogramming JARVIS whenever they wanted to get around him, reaching inside and mucking about, like they weren't sticking his fingers into his brain, and Fury wouldn't – "Stop talking over him, for fuck's sake!"

Well. If he'd wanted attention, he certainly had it now.

The shawarma-noticing part of his brain noted that it was probably a good thing that he hadn't gotten his coffee yet, as he almost certainly would have either knocked it over or thrown the mug, and then he'd have wrecked a screen and had to replace it – and so much of his Tower already needed replacing. The rest of his brain was staring at the wall, where one of the equations had fled to, directed by an errant movement of one of his hands. He couldn't look at Fury. The equation – it meant next to nothing all on its own, without any context, without any -

Just like you. What is your legacy now, in the face of such a vast universe? In the face of all those that you have killed? The voice in his head sounded like Loki, but it wasn't. It never had been before, at least. And the Void – no. That wasn't Loki. Though he could damn well understand why Loki had gone completely wacko, when only glimpses left Tony staring at the walls, hands clenched into fists to stop them from shaking, trying to keep from remembering the thing that dwelled there –

"Tony," that wasn't Fury. He could almost feel the Meaningful Glances being passed between Fury, Natasha, and Clint, the former looking for confirmation of something from the latter two, who appeared... uncertain. Only the shawarma-brain cared. The rest of him was locked onto the equation, considering it.

"Tony?" the Captain tried again.

He blinked at the equation. Waved it away; it dissolved. Stuffed his hands in his pockets to hide the shaking. Why were his hands shaking? He was fine. Loki had seen to that.

You will watch the worlds die, and know that you did this.

"Right, I got... stuff, to do," Tony said stiffly, and bolted for the door.

The Tesseract and Loki's Spear had been kept in the Tower. Thor was quite insistent on taking the Tesseract, at least, back to Asgard, and Fury seemed disinclined to argue – more power plays against the WSC. Loki, however, was in SHIELD custody at the moment, in one of their underground bases, buried under a hundred tonnes of concrete. Thor had informed them that it made a better prison than the aircraft carrier, so long as Loki remained gagged.

"Energy I can manipulate," Tony mumbled to himself as he stared at the softly glowing cube. The Spear lay supported beside it, the energy in it quiescent, for now. Energy. He liked energy. Hey, who didn't? But energy was his thing, was what was keeping Stark Industries not only afloat, but booming – everybody loved energy, especially the clean, cheap type. The force-field that had surrounded the Tesseract, the way JARVIS had immediately noted it as impenetrable, unable to be manipulated by anything that he had at his disposal... he should have known. He should have known to grab the damn Spear.

He'd repaired the bifrost in the other Asgard, but that had been as much guesswork as it had been understanding; if the device hadn't been symmetrical, he'd still be stuck back there – unless whatever had pulled him back to Earth had decided to pluck him from the ground instead of while in mid-transit. So much of the physics of how it worked still eluded him, just as much as it eluded Foster. "But magic is just science..."

"You sure about that?"

Tony froze. He did not look toward the corner of the room where the voice had come from. He didn't answer. He couldn't. That wasn't – that wasn't Rogers-Steve. There was too much experience in that voice, too much death.

"Just because you won't look at me doesn't mean I'm here."

He bowed his head, not daring to blink. Responding was out of the question. Despite his countermeasures, SHIELD might still have managed to bug this room – he couldn't let them catch him talking. To himself. Which was a bad idea anyway. He talked to himself all the time, but when he actually started hallucinating a response... maybe he was wrong about needing sleep. He didn't feel tired, but –

"You should be careful about the arc reactor. If you're hallucinating me, you might have hallucinated those clear x-rays," Steve said. He sounded concerned. Well, okay, maybe he had a point – although it wasn't as if Tony had planned on taking the thing out anytime soon. But the arc reactor had been dead when he'd gotten back to the Tower – hadn't it? Had he hallucinated that, too?

"How far does it go?" Tony asked, still staring at the cube.

"Dunno. I don't even know if I'm real or not. I could just be your subconscious. You'll figure it out – you're a genius. You can figure out anything." A small warm spot bloomed in Tony's chest at Steve's voice, which was – that was pathetic. He was getting an ego-boost off of a hallucination. That was outright sad.

"Right," Tony muttered, ducking his head.

"But..." Steve's voice turned worried again. "I'm right when I say that something broke in your head, Tony. You don't go looking at something like that thing and get away unscathed. You need to be careful."

Truth crawled up Tony's spine like a worm, inching its way along his vertebra and cozying up inside his brain stem. Tony shut his eyes, waiting for Steve to speak, trying to resist shaking all over like a dog ridding itself of fleas. It wouldn't do anything. Steve – or the hallucination thereof – was right. The last bridge, when he'd fallen... and he still had no idea how he'd managed to get back home, if it had been chance (vanishingly unlikely), or the norns, or just Loki being kind to be cruel. He still didn't really know how the bridge worked in the first place. How had he seen back from within it? How had he gotten back to Earth?

"Fuck," he mumbled to the cube. There were SHIELD's attempts, and Foster's – laughably primitive next to the bifrost, which was itself the caveman's imitation of the Tesseract. "What do you use to travel between universes?"

"Dark energy," boomed Thor's voice from behind him, and Tony nearly jumped out of his skin, one hand twitching up to cover the arc reactor before he could stop it.

"Where the hell did you come from?" he half-yelped, turning to see Thor standing beside the new pedestal that Bruce had set up to take readings on the Spear. Steve – real-Steve, Rogers-Steve, young-Steve, stood awkwardly by the doorway. The hallucination was nowhere to be seen – if he, it, ever had been.

"Fury ended the meeting some time ago," Thor declared, his voice as formal as always. He stepped forward, until he stood side-by-side with Tony, staring down at the Spear. "You should not remain in the presence of this... thing overlong, Man of Iron," he advised, disdain for the weapon clear in his voice. "Even if my brother's influence were wholly removed from it, I fear it would remain as insidious as before. It has a mind of its own."

"You can sense that?" Tony asked, before continuing with the same breath, "No, wait, ignore that – dark energy. You mean like dark energy-dark energy? What we call dark energy?" He gestured to himself and Steve, then grimaced and flapped a hand at Steve to exclude him from being a part of any group that knew what dark energy was. Steve just shook his head and left, leaving them alone in the room, although the door was still open onto the hallway. Tony eyed his exit. Hopefully he wouldn't start hallucinating Rogers-Steve as well, or... that would be bad. That would be very bad.

Like you haven't already jumped straight off the deep end of the awful pool, Here Be Monsters, a little voice in his head chimed. He was prettysure that that one was his own, at least.

"I do not know," Thor shook his head. "Your terms are often different than ours."

"Right, big help," Tony muttered, turning back to the Cube. Pity. If Thor had some rudimentary understanding of the Tesseract, then that would be... more than SHIELD had managed, for all that they'd been able to point the damn thing in vaguely the right direction.

To his surprise, however, Thor wasn't finished – apparently, not just all muscle and no brains, then. "What on Asgard we call dark energy fills all of the nine worlds and binds them together, although it is not of any of them, truly. It is... of the space in-between. Where the precepts of each world differ from one to the next, it is universal. Yet it is not possible to touch it with real matter. It, too, should not be contemplated overlong." A heavy hand dropped down upon his shoulder. "My brother's mind was fractured as he fell through that Void, and he is not the first Asgardian to go mad after staring into its depths. A glimpse may grant wisdom, Stark – but beyond that lays insanity. Let it go."

He sounded genuinely concerned. Tony wondered if there was a part of him out there that wasn't. The way Heimdallr and Loki had described it, there ought to be infinite worlds, with non-infinite subsets that the Asgardians spanned – so even they had copies. The Loki-brain of that subset had run to this one – had he met the brain of this one yet? Would the two team up? What did the Thor-brain of this subset think of Loki's machinations – was he, like the Asgardians of that other subset, content to merely react to the atrocities that Loki caused, or did he work to anticipate his brother?

If Tony let this Thor – the limited version in front of him – know any part of his plans, would the Thor-brain of this subset try to stop him? Tell one of the Lokis? How much communication was there between each of the parts – limbs had autonomic reflexes, did pan-dimensional aliens have the equivalent? Was there any way he could get Asgardian help without having it all blow up in his face?

His thoughts were scattered when Thor shook him, gently. Tony almost would have expected his 'gentle' to be rather like his indoor voice –still sounding like a proclamation, or in the sense of being shook, bone-rattling – but he actually managed to pull it off quite well. Good thing, too; Dr. Foster was a tiny little woman. Though fierce, from all indications; she'd certainly put up enough of a fight about working for SHIELD for the government to be staying well hands-off, lending funding and keeping an eye out, but not daring to interfere directly.

Tony reined his brain back in. He was being shaken. Right.

A hand thrust itself between Tony's gaze and the Tesseract. More importantly, that hand held a mug, and the rich aroma of freshly brewed coffee hit his nose. Thor chuckled, clapped him once more on the shoulder and finally wandered off, while Tony reached out quickly and greedily took the mug before it could be withdrawn.

"JARVIS said you weren't responding to his, uh, inquiries about the coffee, but that you'd probably like some anyway," Steve said awkwardly, stepping back as Tony buried his face in the mug. Ah, coffee. It was his sixth or so mug today – not counting any of the mugs he'd consumed before the clock struck midnight; he might or might not need caffeine to avoid sleep anymore, and he might or might not still be addicted to it, but it was coffee. This one was just as much ambrosia as the first mug. JARVIS always made the best coffee. Far better than Tony's coffee, though like anything Tony might make for eating or drinking, that... wasn't hard.

"I was worried the little robot might drop it," Steve said when Tony didn't answer. Instinctively, Tony bristled – but Steve's tone wasn't dismissive. If anything, it was curious, maybe a bit... amused? Yet worried. It couldn't possibly be – affectionate? There was a wealth of information there, drawing Tony's attention. Steve – Rogers – was not supposed to be complicated – the other Steve had been (was?), but he was older. Settled. This Steve, new and uncertain, showed one emotion at a time, and if that emotion was quite often fake, well, Tony could appreciate the need to 'fake it 'til you make it'.

He stared at Steve, who looked back guilelessly. Tony's eyes narrowed. Okay, sure, Captain America was as honest as they came, but was that a bit too guileless? What was he up to? He was –

– trying to distract him from the Tesseract, one hand casually moving to close the lid on the box.

Tony rolled his eyes. "I don't need an intervention!" he snapped, putting one hand out to prevent the lid from being shut.

"Too bad, because you're getting one," Steve said, and if he'd said it in that biting tone he'd used when hurling insults at Tony's character – valid insults, Tony granted, but – or even as a command, then Tony would have snapped back, harder. The other Steve could command, on the field or off; on this Rogers, it sounded false to someone who had seen his war movies, had seen him right after he was unfrozen. Even now Tony could see he was still too off-balance. But instead of commanding Steve just smiled slightly, looking more goddamned cheerful than Tony had ever seen him before, and he pushed the lid down with enough force that Tony either had to move his hand or start working on designs for a prosthetic thumb, and really, he'd prefer to get the eye done first, one thing at a time –

- no, no, that was inefficient. Hell, the entire design was inefficient, although it was an idea worth pursuing. Catching up to Loki was one thing, killing him was another – back on Asgard, he'd hit him hard enough to paste any human, to no apparent effect. If he'd been faster, with the lasers – but that was a system-wide problem, and needed a system-wide solution.

Human enhancement had such a shitty track record, the one shining example standing in front of him notwithstanding.

Bruce would never forgive him if he found out Tony was even considering it. Pepper would never forgive him.

But.

"Pizza?" Steve offered, and Tony sighed, letting himself be distracted.

The full scan-sweep JARVIS was running wouldn't be finished for hours yet, anyway, and some of them were harmful to run in the presence of living things.

The next day, Thor, Loki, and the Tesseract went back to Asgard – their Asgard. Tony watched the device that Selvig had cooked up on Thor's instructions – which he'd said came straight from Odin – turn and click as Loki took it. The energy crawled over them, and they flashed away, but it was different from the portal – closer to how the bifrost worked. There was no sight of the other world they were entering – and there was no gap in-between.

He'd spent the morning picking Selvig's brain, in-between needling Bruce until he finally agreed to delay any flights out of New York and stay at the A-Tower for a while. He couldn't really call it the Stark Tower anymore, not with all the letters missing. If he'd been the type to believe in such things, he might have thought the A prophetic, but even if there were Norse gods running around he'd wait to believe in a subtler, higher power until he saw proof. And even then – any god that bothered with signage instead of saving people from the massacre wasn't a god worth worship.

JARVIS had taken time away from his continuing infiltration of the Helicarrier to forward him a compilation of all research materials that could possibly relate, Bruce was busy getting familiar with his own lab (previously Tony's other spare), and Pepper was back in DC, frustrated with him after getting the brush off the day after the invasion. She'd been concerned over the nuke. He'd been setting up... this.

Tony looked around to make sure that neither Natasha nor Clint was hiding somewhere in his lab – though it was more of a check to see that nobody had just wandered in, since there was hardly any way he was going to be able to see either if they were actually hiding – and pulled the dramatic red lever that he'd installed at about 3am. Connections lit up between the cannibalized Mk VI's reactor and the lab power, and then severed between the lab and the rest of the Tower. Shielding hummed to life, or, in the case of more physical shielding, slammed down over outer access ports and consoles, locking into place and preventing wired or wireless interference.

"Disengagement complete. We are now fully off-grid," JARVIS announced – or rather, his clone did. This version of JARVIS would remain cut-off from his twin – to leave them linked would make this entire exercise pointless.

"You want my attention, Fury, you can damn well knock," Tony muttered triumphantly. SHIELD would have a hell of a time hacking his stuff with no way to make a connection. Asgard... Asgard was another matter, but one he hoped to soon have a defence against.

The completed scans of the cube were laid out before him. Steve and Thor, both of whom had been irritatingly persistent about distracting him, were gone their separate ways. Pepper was – Tony felt a twinge in his chest. Pepper would understand. And if not – well, at least she'd be alive. If he could figure this out in time.

Tony got to work.

...

A million thanks to my beta, Cyphomandra, for her enormous help with this and everything else in this series. Any errors, misunderstandings, or deficiencies that remain are, of course, entirely my own fault.