"Take a picture. It'll last longer."

Steve realized he'd been staring – and not just staring, but gawking like a moron, his mouth actually hanging open. He quickly closed it and lowered his head, embarrassed. "Sorry."

The others were getting up now, coming to greet and shake hands with their visitors from an alternate universe. A woman who must have been Scarlett Johansson's stunt double came up and gave Natasha a hug. Questions were asked and answers were offered, and Steve realized that Nat and Hayley were both watching him out of the corners of their eyes. They were worried he'd do or say something stupid. They had every cause to be.

Sebastian Stan got up and came closer, looking Steve over cautiously. "So as Bob explained it on the phone," he said, "you're actually Steve Rogers, or at least you believe you are, and you're here to make these aliens go back to the other universe."

"Yeah, that's about right," said Steve. He could guess what this man was thinking, and he had better say something to reassure him – and the women – that Steve had a grip on himself. "Sorry for staring. I know you're not him."

"Don't worry about it," Sebastian replied. "It could be worse. You could be in somebody's Stucky fanfiction."

Steve was about to ask him what that was, then realized it was a portmanteau of Steve and Bucky. That, in turn, reminded him of the drawings he'd seen for sale at the convention, and he realized, "oh."

"I don't get it," Sebastian added. "I just want to kiss Scarlett Johansson, just once, and they don't want to let me have that! You got to do it, Mark got to do it… when's it my turn?"

This was spoken like it was part of some personal joke, but if so, Steve was of course not in on it. "I… I don't know," he said, and something inside him clenched as he realized that sure enough, this had been a mistake. Steve had nothing to say to this man who looked like Bucky but wasn't, and Sebastian had nothing to say to Steve. As before, this universe contained nothing but shadows of things Steve wished he could have – shadows designed to taunt him in the most painful way possible.

A moment went by in grinding silence despite the conversations going on in the background, and then Sebastian said, "he's gonna be okay."

"Huh?" asked Steve, who thought he must have missed something. The statement didn't connect with the joke about wanting to kiss Scarlett.

"Bucky," said Sebastian. "I'm not supposed to give out spoilers, but he's gonna be okay. I've already shot my cameo for Black Panther, and after that I'm gonna be in Infinity War and Avengers Four. Don't stress too much. My contract was nine pictures. Depending on if you count the cameos I've got at least three to go."

Three mores movies? Bucky would come out of cryo okay and be alive and well for… honestly, three more movies could be anything from two weeks to twenty years. Either way, Steve shouldn't be able to know that yet – that was exactly what Bob had been talking about over dinner at the hotel, about ruining future plot points. Yet Steve couldn't bring himself to worry about it. He felt like he'd been carrying a boulder around without realizing it, and now somebody had lifted it away. Bucky was going to be all right.

"Thanks," he said, with a relieved smile.

Sebastian clapped him on the shoulder – gingerly, as if afraid Steve would flinch away, but he didn't. "Don't mention it," he said.

The rest of the world began to come back into focus. Individual voices emerged from the distant murmur, and Steve heard Colonel Rhodes ask, "what about Smaller Don?"

"I'm gonna be Spider-Man," said Donny. "I've always wanted to be Spider-Man."

"The costume won't fit, though," said Colonel Rhodes. Steve wondered if the Spider-Man costume had been made for 'Bigger Don'.

"What, you think I don't have my own Spider-Man costume?" Donny asked.

Rhodes chuckled and shook his head. "How silly of me!"

Bob took a head count and made sure everybody was present, then said he'd arranged for somebody to stop by with their costumes. Before the group separated, Steve did get to meet Chris Evans' own stunt double – this was a guy named Sam, which seemed fitting enough. Steve was sure to give him a smile and a firm handshake and to tell him he appreciated his hard work. Then Colleen showed them to a flight of steps, and they descended into Houston's underground walkways.

Steve had been picturing something dark and secret, cramped concrete hallways with lots of pipes, but they turned out to be more like an unground shopping mall. There were tiled floors, benches, and potted plants, and the walls were lined with cozy-looking little shops and kiosks, all closed up for now but ready to open again the moment the city was safe. The area was intended for use by pedestrians, but for employees and emergencies there were several little vehicles, like electric golf cards, parked next to an information desk. Colleen started up one of these, and Steve, Nat, Thor, Loki, and Kevin piled into and onto it. The engine made only a soft whirring sound, but even that seemed very loud and echoey in the big, empty space.

"I always enjoyed giving the tours," Colleen said, turning down a south hallway. "Once you get into the back parts it feels very secret-government-project-y."

That seemed a strange thing to say in the surroundings they were in, but after a few minutes of driving through the wide shopping tunnels, they stopped to open a gate with an authorized personnel only sign on it and entered something more like the utility spaces Steve had been picturing. With the city evacuated the lights were out, but the little cart had surprisingly powerful LED headlights, and Colleen gave the impression she could have found her way even in pitch darkness.

She drove them to a dead end at a set of metal shutters, where she punched in a code on an access panel. The shutters rolled open onto a narrow, concrete-walled tunnel that vanished into the dark. A switch turned on a line of dime fluorescent bulbs in the ceiling, and their flickering greenish light seemed to show the tunnel vanishing into infinity. Colleen climbed back into the driver's seat, and they continued on their way.

This section of the tunnels didn't echo as much, but in a way that was worse. Steve could remember sneaking into underground HYDRA bases during the war, and the oppressive feeling of the earth above weighing down on top of them. It was something he'd tried not to think about back then. Since his return he'd looked some of those places up, and learned that most of them had collapsed in the ensuing seventy years. That was not something he needed to think about now. He focused on looking straight ahead, wondering if they'd meet any of the escaping JSC employees coming the other way.

It was about a half-hour drive. The little cart was slower than a car would have been, but the direct route and lack of traffic helped to compensate. After perhaps twenty minutes they ran out of fluorescent lights and from there on they were entirely in the dark, with the vehicles headlights briefly shining on painted pipes and bundles of wires as they passed. The sight of a light on ahead was a relief, and it grew closer and closer until it was revealed as one incandescent bulb above another metal door. Colleen brought them to a stop.

She punched in another code, and rolled the gate open. "Welcome," she said grandly, "to the Johnson Space Centre."

It was probably impressive on the surface, but the area they entered was another dim underground hallway with visible pipes and ducts in the ceiling and equipment and furniture piled against the walls. Colleen led them past doors that led into offices and labs, all of them unoccupied, and decorated with flyers, comic strips, and a couple of posters detailing projects the employees had worked on. She followed the hall to the end, and opened the door to a locker room.

"Here," she said. "Find something to wear."

Some of the lockers had combination locks on them, but most did not, and there were a fair number of clothes, shoes, and possessions just lying around on the benches or on the floor. Bits of junk and filing boxes had been put on top of the rows of lockers for storage, and the whole place reminded Steve more of wartime SSR bases than of a high-tech research facility like the ones at the Avengers Headquarters. He started looking through clothing for something that would fit.

"Try to avoid anything colourful or memorable," Natasha said, pulling down a black t-shirt that had been hung off an open locker door. "Go nondescript."

"Nondescript doesn't work for Thor," Steve said.

"I bet it doesn't," Kevin observed.

Thor grabbed a white janitor's coverall with the NASA logo embroidered on the pocket and held it up against himself. It looked about the right size, so he unzipped it and started putting it on. Natasha found a pair of galaxy-print leggings and the t-shirt, which said Pluto: 1930-2006. She tied a couple of knots in the hem to make it fit better. Steve found a button-down shirt that fit well enough, and a tie with a cartoon alien on it. That was probably nondescript enough for NASA.

"Are you changing?" Kevin asked Loki. He was still wearing the suit and tie from the convention, and had made no move to put on anything else.

"No," said Loki.

Steve knotted his tie and turned to Colleen. "You mentioned some kind of weapon against the Chi'Tauri queen," he said.

"Yeah," she nodded. "The one I had in mind is liquid nitrogen."

"That's not a weapon," Steve protested.

"Hell, yes, it is," said Nat, tying the laces on a pair of baby blue chucks she'd found somewhere. "Liquid nitrogen is kept at minus two hundred degrees centigrade. Anything it touches, it'll freeze on contact."

Kevin chimed in. "When it boils, it makes a heavy, cold mist that hangs around for a minute or so. Useful for putting out fires and suffocating your enemies… although that's discouraged."

"We've got lots," Colleen said. "So much of our equipment needs to be kept cold."

"And if we can freeze the Queen instantaneously she'll be in much better condition for your scientists to dissect later," Nat said cheerfully.

Steve wished she hadn't said freeze instantaneously. It was a phrase he'd heard his doctors at SHIELD use way too often.

"I know where it's stored," Colleen explained, "but I don't work with it personally so I don't have access. We need to find either somebody in cryonics or somebody with a master key."

Under normal circumstances, Steve thought, he would have just broken down the door to the storage room. But that would probably have set off an alarm, alerting everybody in the complex that something was up. The Chi'Tauri would come to investigate and then there'd be a fight, which he couldn't do right now… damn it.

Once Colleen pronounced them suitably inconspicuous, they got in an elevator and headed up. Steve closed his eyes and took a number of deep breaths, telling himself over and over to stop being a coward. A whole city full of Chi'Tauri had scared him, yes, but it didn't seem right to be terrified of four. His aching ankle made him very, very aware that he could not survive long falls or heavy blows the way he normally could, and the fear of dying loomed over all his thoughts like a thundercloud. He hadn't felt that since he'd had whooping cough at the age of twelve.

At the same time… he was doing this anyway, wasn't he? Because saving this world and these actors from the consequences of Loki's mistake was the right thing to do. That was a good sign. What was it Roosevelt had said? Courage is not the absence of fear, but the assessment that something else is more important than fear. Serving his country had been more important than Steve's fear of the super-soldier treatment. Ditching the Valkyrie had been more important than his fear of dying in the fireball, even if Peggy would have called him a self-sacrificing wanker for it. This time, keeping the Chi'Tauri from killing people who weren't even from the same universe as Loki was more important than whether Steve got hurt.

A moment later, that train of thought brought Steve to another, less-comforting station – he hadn't said goodbye to Hayley. He'd been distracted talking to Sebastian Stan, and then the group had split up and she'd stayed behind in Pennzoil Place. Her job would be to help stage-manage the little improv play the actors were putting on. It wasn't that Steve thought she would have kissed him and said go get 'em or anything like that and he wouldn't have wanted her to. He did like her, though, and they had in common that they both adored Peggy Carter. She deserved a goodbye.

Or maybe Steve was just fooling himself again. He hadn't said a real goodbye to Peggy, either when he'd crashed the Valkyrie or when she'd died last year. Maybe he wanted to vicariously correct that mistake.

The elevator chimed as it reached the ground floor and the doors opened, and Steve's thoughts dispersed in a puff of panic. There was a Chi'Tauri right in front of them.

He tensed, and out of the corners of his eyes he saw everybody else do the same. The good news was that the alien was facing away from them. The bad news was that it was aiming a weapon at a group of six or seven humans standing across the hall. In front of this small crowd was Ellen Ochoa, the woman from the YouTube video. She was still wearing the same coral-coloured blouse, although now it had a large dark stain on the front, and her arms were held out on either side as if to protect the people cowering behind her. Her chin was up defiantly.

It didn't take a genius to figure out what was going on. Colleen had said that Ochoa had been helping people sneak out through the tunnels. Now she'd been caught in the act and was about to be punished for it. Steve had to do something… but what could he do in his condition?

The Chi'Tauri had heard the sound of the elevator arriving, and turned to look. Kevin and Colleen, neither of whom had yet seen one of their visitors up close, both panicked.

"Shit!" said Colleen, and hammered on the door close button.

"Mierda!" said Kevin at the same time, and hit the button for the top floor.

"Scatter!" Director Ochoa ordered the people behind her.

The employees ran off in both directions, which got the Chi'Tauri's attention again. It looked left, then right, not sure who to chase, then turned back towards the elevator and met Steve's eyes as the door closed. Steve saw the bruise on its chest next to the biomechanical implants. This was the same individual soldier they'd seen at the hotel and the convention centre, and he was quite sure that it had recognized him, just as he'd recognized it.

That was even worse. If the Chi'Tauri knew the Avengers were already here, they would know that Bob's message was a bluff.

"Jesus, they're huge!" said Kevin, as the elevator rose. "I mean, you know they're huge because you saw the movie and they're like eight feet tall, but that's totally different from it actually looking down at you from eight feet up!"

"We have to get back down there," said Steve. If the Chi'Tauri were a hive mind then all of them now knew that Steve and the others were in the building, and like or not they had a fight on their hands. What could they do now? This whole plan had hinged on not attracting attention, because they were in no shape to fight! Steve was right where he most hated to be, with his hands tied. Accords or no accords, there was nothing he could do to save those people.

"Stop here!" Colleen pressed the third floor button, then pounded on door open.

"What's here?" asked Thor.

"The liquid nitrogen," said Colleen.

"You said you needed a key," Steve protested.

"You guys seem to think you're the Avengers," Colleen retorted.

Steve looked at Natasha, who nodded.

Unlike the one at the hotel, this elevator had the decency to stop at the floor they were hoping to reach. The lack of angry aliens trying to break in from above was helpful as well. Colleen led them u a hallway to a door with multiple warning signs posted on it, and Natasha got to work on the electronic lock.

"There," she said, as it opened with a clunk. "That was easy. I would have expected NASA to have better security."

"Not a lot of people want to steal liquid nitrogen," Colleen observed. "We mainly want to keep the interns from using it for pranks."

"Yeah, but you're the government," Natasha pointed out, with a disappointed pout. She opened the door and turned on the light. Inside the room was firefighting equipment, protective clothing, and a line of cubical freezers that reminded Steve of nothing so much as old top-loading washing machines. It was all very carefully organized and labeled, with big yellow CAUTION signs everywhere. "Then again," Nat mused, "If this is your first alien invasion, you're probably not as important as NASA is in our universe."

"We're probably not as well-funded," said Colleen.

"When we get money, we like to spend it on rockets instead of fancy locks," Kevin agreed.

Steve had hoped they'd be allowed to open the freezers, but instead Colleen went for a shelf of canisters that looked an awful lot like ordinary fire extinguishers. She began passing those around.

"Is this all?" asked Thor.

"Not what you were picturing?" Natasha guessed.

Thor examined the extinguisher, hefting it in his hands and turning it over to read the instructions. "I had imagined something more like the equipment the ladies used in Ghostbusters," he confessed.

"Oh, you finally got to see it, did you?"

"Yes. Loki and I watched it during the night we spent at Bob Downey's house, while you two were in jail," Thor said. He took one of the firefighting hatchets down from the wall and swung it experimentally, then tucked it into the belt of his coverall. "It is not one of the greatest sagas of your people, but quite diverting nonetheless."

"I liked the original better," said Loki.

They figured the Chi'Tauri would be watching the elevators, so they took the stairs back down. This was a laborious journey on Steve's bad leg, with his crutch in one hand and the nitrogen fire extinguisher in the other, but he insisted on going first.

"This is the twenty-first century, you know," Colleen told him.

"I'm not being chivalrous," said Steve. "If we meet any Chi'Tauri, we might need to use the nitrogen. Loki, Thor, and Natasha should stay in the back to save theirs for the Queen, in case we can't come back for more. That puts me in the front."

"Along with us," said Kevin firmly.

"If you're okay with that," Steve said. He hoped they were up to it – these two women were scientists, not fighters.

At the bottom of the steps, Kevin eased the door open and they peeked out. There was nobody there now – the fugitives had scattered as instructed. Not too far away, though, somebody was weeping. The sound was just barely audible. They followed it down the hall and into a lobby centered around a life-sized model of some kind of space probe, with a big radio antenna mounted on a foil-wrapped body as big as a grand piano. It was on a dais with stanchions and ropes to keep people from climbing it, but the Chi'Tauri soldier in the room was ignoring these. It had one foot up on the platform, the better to loom over Ellen Ochoa, who was cowering behind the model.

"They're not the Avengers!" she was pleading. "They're just actors! They play superheroes in the movies! There are no superheroes here, and even if there were, I didn't call them, I swear to you!" She looked up into the Chi'Tauri's face. Its skeletal teeth were bared in a snarl, and the woman quickly looked away again.

She was trying to save her own skin, and the lives of her employees. Steve could hardly hold that against her, but she was ruining their plan. If the soldier seeing Steve in the elevator had been the death of it, Ochoa telling him they didn't have any Avengers might be nailing the coffee shut. Steve stepped into the doorway.

"We are the Avengers," he announced, conscious of how silly it was to say that while leaning on a crutch, holding a fire extinguisher, and dressed in a button-down shirt and chinos that were a good two inches too short. "Stand down!"

Was that the right thing to do? Or was it, as Peggy would have said, the act of a self-sacrificing wanker?

Chi'Tauri didn't have much facial expression, but the Soldier turned to look at him, and did an admirable job of appearing skeptical. Natasha and Thor stepped out to join him, also dressed in their stolen civvies and without weapons besides the nitrogen. When Thor had walked into the museum in Oslo in his jeans and sweatshirt, he'd looked like a warrior nevertheless. Right now, Steve was pretty sure they all looked like idiots. Sure enough, after taking in the sight of them, the Chi'Tauri began to laugh.

"No Avengers!" it rasped, in between deep, guttural grunts that were entirely unlike human laughter but at the same time perfectly recognizable. "Only human fools!" It turned away from Ochoa hiding under the spacecraft, and raised its weapon.

Several things flashed through Steve's brain in quick succession. He knew he couldn't take the plasma rifle out of the alien's hands – its grip was too strong. He could hurl himself in front of the weapon, to absorb the blast and buy time for his allies, but Peggy would definitely have considering that self-sacrificing wanker-hood and he had to remember that this wasn't his body to get killed in. He didn't have a shield to throw, only himself, a canister of liquid nitrogen, and a crutch.

So he threw those. He dived at the alien's leg as it moved away from the carpeted dais supporting the models spacecraft. Off-balance and in the middle of taking a step, it tried to avoid him and fell backwards, landing on the model and breaking it – it was nothing but plywood under the paint and foil. Ochoa managed to wiggle out of the way just in time, and crawled under a bench. Steve, however, was pinned painfully between the alien and the edge of the dais, with the corner digging into his back. Struggling, he managed to throw his crutch across the Chi'Tauri's neck and squeeze, pressing the aluminum as hard as he could into whatever this thing had for a windpipe.

The surprised Chi'Tauri kicked and struggled. It fired several involuntary shots into the ceiling, destroying the panels and bursting the fluorescent bulbs in showers of glass. The sprinkler system went off, spraying everything with cold water. Using its free hand, the alien scrabbled at the crutch, its claws raking Steve's arm as it tried to get free. He wound both arms around the metal, securing the crutch in the crooks of his elbows so it couldn't be moved without tearing his arms from their sockets.

If the Chi'Tauri struggled much harder, it might do exactly that.

"Steve! Let go!" Natasha ordered.

He saw her coming with her fire extinguisher ready, and he dropped the crutch and pulled the plastic satellite dish from the spaceship model over himself as if it were a shield. Through that, Steve could hear a hiss as Nat finished what she'd started in Canada, and emptied the contents of the extinguisher into the Chi'Tauri's face. A white mist rose up around Steve as the temperature in the room dropped suddenly, and the spray of water hitting him from the sprinklers became pellets of ice. He found himself gasping, unable to breathe as the cold fog filled his lungs.

He almost passed out. Flickering lights danced in front of his eyes as he sank into an all-too-vivid memory of cold and pain and lack of air as the Valkyrie entered the arctic water… and then somebody slapped him.

"Steve!" said Natasha.

Steve opened his eyes. He'd been dragged out from under the plastic dish and was now a few yards away, sitting against the wall while Nat shook him. The Chi'Tauri was lying on its back in a mess of plywood and foil, covered with frost from the frozen sprinkler spray and not moving. Had they finally found something that worked?

Thor raised the axe he'd taken and tried to drive it into the Chi'Tauri's neck. It bounced off, leaving him cursing and shaking his shoulder. The alien was frozen solid.

"It's dead," Steve said out loud, not because it needed saying, but because he needed to hear it.

"I hope so," said Nat. "Although you never know – it might revive when it thaws out."

That was worryingly reasonable. After all, it was exactly what Steve had done. He started trying to get up, and found he couldn't. His head was spinning and his heart racing, and his shoulders ached from how hard he'd been holding on to the crutch. There were also bloody scratches down his left arm.

They couldn't stay, though. The other Chi'Tauri now knew not only that the Avengers were here, but that one of their number was unconscious or dead, and they would show up any minute now to investigate. Back in his own universe Steve would have used what he'd learned fighting this one to take on the rest, but he couldn't do that here. He had to let Natasha and Thor help him, while Loki went up to the frozen Chi'Tauri and yanked the plasma rifle off its arm.

"If you want to be sure," he said, "be sure." And he shot the downed alien in the face, taking its head clean off.

Kevin and Colleen had run around behind the dais and the remains of the model spacecraft to get Ochoa, who was now soaking wet as well as sweaty and dishevelled. "Are you okay?" Kevin asked.

"I don't know," said Ochoa. "I might never be okay again."

"We have to reach the Chi'Tauri Leviathan in order to confront their Queen," Thor told her. "Do you know where their landing craft are?"

"In the green space, behind Old Mission Control," said Ochoa. "I can show you the way." Kevin and Colleen helped her to her feet, and she looked nervously up at Thor. "You know, we've been joking about it all day. Call the guys who play the Avengers and maybe they'll get scared and go away. I can't believe you actually did it."

Nat pointed to the NASA women. "You three need to get out. We can find the landing craft ourselves. You get to the tunnels."

"I can't," Ochoa protested. "Not when my employees are still in here!"

"You can't do anything more in here," Nat told her. "But once you're outside the scrambled area, you can call Bob and Hayley and tell them to call off the broadcast. Now that the Chi'Tauri know we're here, it probably won't work and it's an unnecessary risk."

"What do we tell them about what you're doing instead?" Kevin wanted to know.

"We're winging it," said Nat grimly. "We've wung it so far, we might as well continue."

"Wung?" asked Steve.

Natasha nodded. "Winged just doesn't sound right."