Tony was in the middle of clearing up the debris from his last attempt to upgrade his armour when Pepper paged down saying that Captain America was there and asking if he could come down. Which was weird, because Steve knew he had a standing invite to wherever Tony happened to be, but he was also generally polite, so that was probably it.
Steve showed up at the door to Tony's lab a few minutes later–cowl and shield gone, but still in uniform–and took in the shrapnel spread across the lab with a little smile that made Tony's knees go week. "Is it safe to come in?" he asked, and Tony threw an oily rag at him.
"Of course," Tony told him. "Actually, yes, do come in! You can help instead of just standing there looking ornamental."
Steve's smile widened as he stepped across the threshold and into the lab proper. "So what'd you blow up?" he asked, and Tony would have said that was unfair, but well, obvious explosion.
"I might have overestimated the capacity of the new gauntlets," he admitted. "Or I messed up my wiring. Or both. I haven't worked that out yet. If you could move that beam for me, I should be able to get at the processor and check the outputs from right before it went."
"So I'm your own personal crane, now?" Steve asked, but he was still smiling, and that still made Tony want to do just about anything but work out what went wrong with the damn armour. It also didn't help that Steve pretty well sashayed across the lab, ignoring the beam, eyes raking up and down Tony's body in a way that Tony would have thought of as frank sexual assessment and/or mentally undressing Tony, only Steve was the one doing it. "Hey, you're bleeding," Steve said when he was close enough for Tony to smell leather and metal polish and whatever old-fashioned spicy aftershave Steve insisted on using, as well as something overheated and sweet that might have been left over from his last fight with a goo monster. "Are you okay?"
Tony touched the cut on his forehead, and winced. "Fine," he said. "Just a scrape. You know head wounds: always look worse than they are."
"Until they kill you," Steve corrected. His voice was deepening, and his pupils had started to go dark, in defiance of the lab's brightness. Tony felt the hairs on his neck rise, but there wasn't anything wrong. Steve was concerned about him, and okay maybe he looked a little turned on right now, but hadn't that been what Tony wanted all along?
"Seriously, I'm fine," Tony said, absolutely not taking a step back, like a deep dark part of him was screaming he should. "It's a scrape, not a concussion. I checked."
"Still." Steve took another step forward; Tony felt the creeping sensation run all the way down his spine. "Let me take a look."
He reached forward, and Tony again didn't flinch back, but he felt his hands coming up between them entirely on instinct. Now he was starting to worry. He wanted this–he'd literally dreamed of something like this happening and woken up rock hard–so why was every subconscious part of him urging him to run?
Instead of tipping Tony's chin to look at the cut on his temple, Steve took both Tony's arms by the wrists and leaned in closer.
"What...?" Tony started too ask, but he was starting to feel groggy. Maybe he did have a concussion after all. It was good that Steve was checking up on him. In fact, he was feeling a bit faint, too. "I think I'm..." he tried again, but he was falling. Steve shifted his right arm to catch him around the shoulders, but didn't lower him to the ground. He wasn't looking at Tony's head wound, or even his face, either. Instead, his expression was focused on Tony's wrist, on the little scratch right above the redial pulse point. The scale mail on Steve's costume dug into Tony's bare arm, or did it? It felt more like...
Tony shook his head sharply, trying to clear the haze. Something was wrong. There was something wrong with Steve. He... he had....
"Shh," Steve said, voice deeper still, hypnotic. "Shh. You're all right, Tony. Everything will be all right. Just let me take care of you."
He had fangs.
Steve had fangs. All the subconscious warnings screamed at him at once, and Tony finally put it together. The asking to come in, the feeling that something was off, the hypnotic voice, the fixation on blood, and most of all the fangs. "Vampire!" Tony snapped, and tried to twist away.
It was too late. Not!Steve was holding him with a grip far stronger than even a super soldier, and even Tony kneeing him in the balls only made him smile more widely.
"I have you, Tony," Not!Steve said, and pulled Tony's wrist up to his mouth. He licked delicately at the blood, the contact making Tony shiver and the haze in his mind thicken. If Tony had wanted to get away, he should have listened to his instincts five minutes ago, now...
The door slamming open startled Tony enough to try twist away again. He jerked his left wrist free at the same time as Cap's shield thwacked Not!Steve in the back of the head with enough force to knock them both flat.
Not!Steve landed on top of Tony, winding him, but Tony bucked and flipped him off, so that only Not!Steve's death grip on his wrist held them together. He tried to yank free again, but Not!Steve really had a hold on him, and also seemed to be turning into a lizard. The scales Tony had felt had not been mail, but the creature's skin, and the fangs were something that would haunt Tony's nightmares for a long time. It's claws were digging into Tony's wrist, making it impossible to pull away without tearing his flesh, and Tony had to choke back a scream as a long tongue uncoiled and licked at the blood again.
"Get the hell off him!" That was actual, real, honest-to-God Captain America–albeit in his shorts with no shirt, shoes or cowl. He did have his shield though, and he slammed it against the side of Really!Really!Not!Steve's head. "Let him go!"
Not!Steve hissed at Steve who punched it in the nose at the same time as Tony rabbit kicked it in the ribs and yanked his wrist free at last. He rolled away, which gave Steve the room to get another few hits in, and wrap what looked like a vibranium-laced chain around the creature's wrists, which had the added bonus of knocking it out. It seemed like vibranium was to vampire lizards as silver was to werewolves, or at least that was what Tony assumed was going on.
"So," Tony said. He was lying on the floor just propped up on his elbows, holding his wrist to keep the bleeding down. "How was your trip to Latvaria?"
"I was in Weehawken," Steve said, still panting, a lot like he'd run flat out all the way from Jersey, barefoot and in boxer shorts.
"Figures," Tony said. "Are you okay?"
"It didn't like super soldiers," Steve said, minimising the part where it had somehow gotten his clothes off him, even if it couldn't touch his shield. "What about you? Looks like it did a number on your lab before it pinned you down."
Tony started to laugh, knowing he was giddy from the fight and from whatever pheromones that vampire lizard had whammied him with, and also not caring. "No, I did that. It just asked how I was, and I folded."
"Oh." Steve frowned. He was still crouched on the floor, with one knee planted in the lizard's back, and how he was looking at Tony like he was disappointed about something. "So I guess it must have showed up as someone pretty special, huh?"
"Wait." What Steve said hadn't really tracked, but it had just occurred to Tony that Not!Steve hadn't stolen Steve's clothes for its own use, since it could appear however it liked, and Steve also wasn't wearing them. "What happened to your uniform?"
"Uh..." Steve said. He rubbed the back of his neck and looked down at the lizard pinned under him. "It has a localised perception field, and I thought it was..."
Tony held up a hand to silence him. "Someone you'd take your clothes off for, apparently. In New Jersey." Tony very much didn't want to know who could get that close to Steve. There was a reason that he pretended Steve didn't have a life outside the Avengers Tower and occasional totally-not-actual dates with Tony. It wasn't that he didn't wish the man well, but if he actually saw Steve go out with someone the way Storm flirted with Thor, he knew he'd curl up into a little green ball and die. Tony Stark: The Anti Hulk.
"Yeah," Steve said, and he was flushing all the way down his chest now. Tony made himself not look. "I guess that should have tipped me off."
"It just showed up here as you," Tony said, trying to keep the joke going, since he was failing at the not staring thing. "Guess that says something about my love life right now."
Steve drew in a sharp breath, and stared right back at Tony.
"A localised perception field that manifests as the person its victim most desires," Steve clarified, still blushing, but at least meeting Tony's eye now.
Tony wanted to look away, but couldn't drag himself away from Steve's gaze, not when it was so blue and so earnest. "Okay, so that cat's out of the bag," he said, making his voice steady, but failing at casual. "I hope we can—"
"And I saw you, Tony."
"Oh," Tony said. Steve was damn near naked, because he'd thought he'd seen Tony, the person he most desired. "Well. That saves time." He pushed himself up enough to run a hand up Steve's arm, finding only smooth skin. "Just checking that you're not another lizard person. That'd be my luck."
Steve was grinning at him, a broad and completely dopey grin that Tony had never fantasised about because he'd never seen it before. "Just me," he said. "Though if you want to check for scales in a few more places, I can't say I'd object."
"Yeah. Sure," Tony said, heart singing, barely feeling his wrist now, not seeing what a disaster zone his lab was, because Steve was right there, and Steve was smiling like Tony lit up his world. "Let's give it a whirl. For science."