Tony stared at Peter blankly. "What do you mean, you think Cap's been turned into a vampire?"
"I mean, I think Cap's been turned into a vampire," Peter replied, pulling off his Spider-Man mask so Tony could see his face. He looked worried. "He's been acting really weird since he got back from that meeting with Dr. Pym this morning."
"Peter," Tony said slowly, "you do realize that there's no such thing as vampires, right?"
Peter stared at him, wide-eyed. "That's what you said about zombies, and look at what happened on Halloween!"
Behind them, someone cleared her throat pointedly.
Tony and Peter both turned around to face the rec room's doorway. Jan was standing there, an amused expression on her face. "First of all," she said, holding up a finger, "those weren't actually zombies. Those were a magical experiment of Doctor Doom's that went wrong and tried to take over New York."
"Or so he claimed," Peter muttered. "They sure looked like zombies to me. And do any of us actually believe that it wasn't an intentional invasion?"
Jan raised an eyebrow, and Peter stopped talking. "Second," she said, holding up another finger, "why on Earth are the two of you talking about Halloween? I thought we all agreed never to mention it again."
"Spider-Man thinks Cap has been turned into a vampire," Tony said, not even trying to hide his smirk.
She stared at them both for several seconds without saying a word. Then she blinked. "A vampire?" she repeated, turning her attention solely toward Peter. "Do I even want to ask where that idea came from?"
Peter's face turned slightly red and he didn't quite meet either of their gazes.
"Come on, spill," Tony said, rolling his eyes. "We're both curious."
Peter muttered something under his breath.
Jan crossed her arms. "Louder, please."
"He tried to bite my neck," Peter said, speaking so quickly that the words seemed to stumble together. "He said it was because I was part of his team and needed to be marked."
Tony and Jan stared at each other over Peter's head, identical looks of bafflement on their faces. "Cap tried to bite your neck?" Jan asked skeptically, turning her gaze back toward Peter. "You mean Captain America? Steve Rogers? That Cap?"
Peter nodded, his worry even more obvious than before.
Tony glanced at Jan one more time. "I'll go check on him," he said with a sigh.
The moment he stepped into Steve's room, Tony knew that something was wrong. The lights were all out and the blinds on the window were tightly closed, leaving only a slight glow from the alarm clock beside the bed as a source of light.
Frowning, he reached over to put his hand on the light switch. "Cap, are you in here?" he called out.
There wasn't an answer.
"I'm going to turn on the light," Tony said, squinting as he tried to make out if there was any movement inside the room or not. "Speak up now if you don't want me to do it."
There was a rustling sound somewhere on the other side of the room, but there wasn't a reply.
Feeling slightly worried now, Tony hit the light switch. He narrowed his eyes as the glare from the overhead light hurt his eyes, despite him only being in the dark for a few minutes. "Cap?"
Steve was sitting on the floor on the opposite side of the room, pretty much as far from the door as possible while still being in the room. His knees were brought up in front of him, and he had his arms wrapped around them as he leaned back against the wall. His gaze was focused on the carpet.
"Stay away, Tony," he said without looking up.
Tony snorted even though he didn't feel very amused. "Do you really think that's likely?" he asked, starting across the room. "What's going on? You have poor Spider-Man convinced that you've been turned into a vampire."
After a second's hesitation, Steve looked up and smiled weakly at him. Tony stopped in his tracks.
Steve's face was pale and not its usual healthy tone. It was his teeth that caught Tony's attention, though, not his pallor. They were distinctly pointed.
"Okay, that's new," Tony said, his voice sounding strangled even to his own ears.
"It's not permanent," Steve said, sounding slightly sheepish. "It should wear off by tonight. In theory. And I'm not actually a vampire. I don't suddenly have a craving for human blood or anything like that."
Tony blinked a few times as he tried to parse through what Steve was saying. "Wait, what?" he asked. "You know what caused this?"
Steve looked away, a slight flush coloring his unusually pale cheeks.
Shaking his head, Tony took several more steps forward and knelt down so he was at eye level with Steve. "Come on, tell me what happened. It can't be any worse than the incident with Wolverine and the toaster."
Steve didn't look like he quite agreed with that statement, but he didn't argue. "Hank dropped a vial of something while I was at his lab earlier," he said, not looking toward Tony. "It interacted with the super serum in my blood and caused, well, this."
Tony reached up and rubbed his temples. "So what you're saying is that Hank Pym turned you into a vampire?"
"Temporarily," Steve said quickly.
"Temporarily turn you into a vampire," Tony repeated. "Just when I think that our lives can't get any stranger, Cap, something like this happens."
Steve slowly looked up, meeting Tony's gaze for a second. He quickly closed his eyes a moment later, his breathing noticeably picking up.
Tony frowned. "Cap, are you okay?"
There wasn't a reply.
"Steve?" Tony asked, his frown deepening.
"Maybe you should go," Steve said, his eyes still tightly closed. His voice sounded shaky. "Let the others know what's going on and check on me later tonight."
Tony opened his mouth to protest, but then he remembered what Peter had said earlier. He closed his mouth and tilted his head, staring thoughtfully at Steve for a moment. "Peter said you tried to bite his neck earlier," he said slowly. "Something about needing to show that he was part of your team?"
Steve's slightly flushed cheeks turned bright red.
"Maybe that he belonged to you?" Tony continued, starting to smile.
"There's a possibility," Steve said, his voice sounding slightly strangled, "a slight possibility, that the interaction between the chemicals in my blood are causing some of my more possessive traits to stand out a little more than usual."
Tony threw his head back and laughed.
Steve finally opened his eyes. "It's not funny," he muttered petulantly.
Tony leaned in, resting his forehead against Steve's. "Should I be jealous?" he asked teasingly. "I mean, you're willing to mark Spider-Man of all people, but then you're trying to get me to leave. If I didn't know any better, I'd think that--"
Steve let out a growl and leaned forward, cutting Tony's rambling off with a kiss. Tony smiled against his lips, kissing back.
A few seconds later, Steve pulled away. He moved his lips down to Tony's neck, nuzzling softly for a moment. "Mine," he said, biting down slightly.
Tony grinned, nipping slightly at Steve's ear. "Yours."