They were sitting down to eat when it happened.
A man, blond and buff and tall, sauntered up to their table with a grim scowl on his face. He stopped in front of them and crossed his arms, waiting impatiently for them to look up. Peter and Tony traded confused glances before indulging him.
“Can we help you with something?” Tony asked, annoyed.
The man’s jaw ticked. “You can help me by not killing my friends.”
“What the hell are you on about?” Tony hissed, checking the cafeteria for any eavesdroppers.
There were none.
“Your room is next to Bucky’s,” the blond said in an accusatory tone, “I know you did it. And I promise you, this is the last thing you’ll ever do. I won’t let you terrorize the crew.”
“You have no proof,” Peter cut in, placing a protective hand on the small of Tony’s back.
“I’ll get all the proof I need,” Steve insisted, “And if I don’t, I’ll kill him myself.”
With that, he whirled on his heel and strode out of the lunch hall, shoulders set back in determination. Peter sighed, shaking his head. Steve was completely wrong about Tony. His sweet lover would never end another’s life; it was Peter who slid a blade along Bucky’s neck the night before. He was going to have to be more careful from now on. He couldn’t have Tony get ejected, especially not because of him.
“Are you okay?” Peter rubbed his back sympathetically.
“Yeah,” Tony nodded, looking mystified, “Honey, would you stay in my room? I don’t feel comfortable with you being alone now that there’s a killer on the loose.”
Peter bit the inside of his cheek to stop himself from smiling. “Of course. I’ll move my stuff when I finish my tasks.”
He didn’t have tasks - not any assigned ones, anyway. He’d given himself a new task as soon as Steve had stormed out of the cafeteria. By tonight, Steve would be dead. Peter wasn’t going to let him lay a single finger on Tony.
When the couple finished eating, they parted ways, with extracted promises from the other to be vigilant of their surroundings. Peter wasn’t worried. Bucky had been the only other imposter on the ship, and there was no one who would hurt Tony other than Steve, who would be taken care of at once. Tony was a whole other story, checking each corner before moving around it, looking over his shoulder at every creak and groan that the ship made. He feared for his life and Peter’s, praying to a god he didn’t believe in that Peter would make it home in one piece.
Peter wandered around the ship until he spotted Steve, who was hunched over an electrical unit and fiddling with some wires. The younger man knelt down to grab one of the stray wires and creeped up behind Steve. In seconds, he had the wire around his neck and was tugging at it, drawing blood from where the wire cut into Steve’s skin, and simultaneously cutting off his air supply. Steve fought against his hold, hands grasping Peter’s in a bruising grip, and his flailing grew more sluggish as the seconds passed. Soon, he was slumping in Peter’s arms, his heavy head falling forward.
Peter dropped him onto the ground, leaving the wire to stick to his pale throat with the help of the blood dripping beneath it. He stepped over the dead body and ducked out of the electrical room, watching for any witnesses before making his way to his room.
His belongings were scarce, a couple changes of clothes and a few toiletries. He picked them all up and carried them to Tony’s room, where he set them down next to Tony’s possessions. Tony joined him in the room half an hour later, looking exhausted. He crawled into bed and tucked himself into Peter’s side, resting his head on Peter’s chest.
“Did you see anything suspicious?” he murmured tiredly.
“No,” Peter brushed a hand through his boyfriend’s hair, smiling at the hum it elicited from him, “Did you?”
Tony shook his head silently, leaning into Peter’s hand and urging him to continue petting his hair. Peter gladly carried on the motion, watching it soothe Tony to sleep. He kept his hand in Tony’s hair when his drowsiness started to overwhelm him, and fell asleep with his lover still clinging to his front.
It didn’t take long for the crew to find Steve’s body. The next morning, Wanda set off to complete her task in the electrical room, and the scream that tumbled out of her lips had everyone racing to find her. They all stood in a circle, staring with wide eyes at Steve’s slack face, and the cooled blood painting his neck in thick rivulets.
The body was ejected, the area promptly cleaned, and soon they were hosting an emergency meeting.
“Does anyone here have a motive to kill Bucky or Steve?” Natasha questioned, fixing them all with a scrutinizing glare, “At this rate, we’ll all be dead by the end of the mission.”
Everyone denied having problems with the dead men. Peter spoke up, too, swearing that he knew nothing about the deaths. He noticed that Tony was oddly silent, his blank gaze trained on the floor. It appeared that Natasha had noticed it, too.
“Tony, anything to say?” she raised her eyebrows.
“No,” the man said shortly.
He didn’t miss the distrustful looks that followed him out of the room. Peter walked with him to their room, concern bubbling in his chest when Tony stayed quiet through the entire walk. When the door to their bedroom closed behind them, Tony cleared his throat.
“You killed him, didn’t you.”
It wasn’t a question.
Still, Peter hesitated before saying, “I did it to protect you.”
“I don’t need protecting,” Tony scoffed, disbelief and disgust evident in his tone, “I especially don’t need you to kill people. Fuck, I’m in love with a murderer.”
Peter wisely kept his mouth shut, watching him pace the length of the room. He winced when Tony reeled his hand back and punched the wall.
“Did you kill Bucky, too?” Tony faced him with an expectant expression, “Did you?”
“He was going to kill you,” Peter pursed his lips, “I had to make sure he didn’t. He was an imposter, Tony.”
“What makes you any different?” Tony snapped, “You killed two people!”
“I did it to protect you,” Peter repeated calmly. “You would be dead if I hadn’t.”
Tony prodded, “If I turned you in, would you kill me?”
“You wouldn’t turn me in,” Peter said confidently.
Tony’s shoulders slumped in defeat. “No, I wouldn’t.”
Peter spread his arms wide and watched Tony debate himself for a few moments. He stepped into them eventually, hiding his face in the crook of Peter’s neck, and Peter’s mouth stretched into a relieved smile.
“I love you,” he muttered into Tony’s ear, planting a small kiss behind it.
Tony relaxed in his embrace. “I love you too, but you can’t kill anyone anymore. I’m not going to be with a serial killer.”
“I won’t kill anyone who doesn’t threaten you,” Peter promised.
That was the only reason he’d started killing people, anyway. He didn’t take any pleasure out of doing it.
“Good enough,” Tony rolled his eyes.