Sirius Black was alone in his dormitory with his best friend Remus Lupin. His best friend James and his best friend Peter were off in detention (somehow, he had gotten away with his portion of the prank that night, and Remus, as always, was unsuspected).

Sirius had just gotten back from a tryst with one of his many lady friends, and Remus raised an eyebrow as Sirius entered the dormitory, his tie askew and his hair a mess.

"Have fun?" the mousy haired boy asked, glancing up from his book.

"You know it," Sirius said with a smug grin, flinging himself onto Peter's bed because it was the closest one to Remus.

Remus just rolled his eyes, and returned to his book.

Sirius stared at the canopy atop Peter's bed for a moment, then rolled over on his side, propping his head up with his hand.

"What would you know about having fun?" Sirius asked, putting an emphasis on the last word.

Remus shrugged. "Not as much as you, that's for sure."

Sirius huffed, then leapt off of Peter's bed and onto Remus's. At this, Remus chuckled, scooting over to make room for him. Hopping beds was a common habit of Sirius's. He'd often sit down or lay down with one of the Marauders on their bed instead of his own.

"Moony, Moony, Moony," he said, cocking an eyebrow.

"Yes, Padfoot?"

"Have you ever kissed a girl?"

Remus rolled his eyes and said flatly, "No, Sirius, I haven't. You lot would have been the first to hear about it."

Sirius made a hrumphing sound and crossed his arms.

"Moony, Moony, Moony."

"Yes, Padfoot?"

"Do you even like girls?"

Remus simply shrugged, his eyes glued to his book.

Sirius was silent for a moment. He drummed his fingers on the side of the bed, and then his eyes lit up. He poked Remus in the side.

"What do you like then?" he asked.

Again, Remus shrugged.

A mischievous grin took over Sirius's face.

"You like boys, don't you?" he said in a low voice.

At this Remus paused, and he looked up from his book. A beat passed before he answered.

"No," he said, and turned back to his book.

Sirius stared at him for a moment, then began in a sing-song voice, "Moony likes boyyyyyys, Moony likes boysssss."

Remus sighed and looked up from his book again. "Shut it, Padfoot, I don't like boys."

Sirius continued his song.

Remus shut his book with a slam. "Seriously, Sirius. It isn't funny." His eyes were dark, and he looked Sirius straight in the face.

"Prove it then," Sirius said, licking his lips.

"How? You want me to go around the castle snogging every girl that passes by, like you do?"

Sirius put a hand to his chest, pretending to be offended. "Excuse me, Remus, I do not go around kissing every girl in the castle who passes by. I've got standards. They have to be pretty. And willing. I snog girls on a voluntary basis only."

Remus rolled his eyes and opened his book again. "Whatever, Padfoot," he said, his voice sounding resigned.

Sirius gave Remus the chance to read about two pages, then poked him in the side again.

"What, Sirius?" he asked, clearly annoyed.

"You still need to prove it."

"Prove what?"

"That you're not gay."

Remus sighed, setting down his bookmark and shutting his book again.

"And how do you suggest I do that?"

Sirius paused, looking at the ceiling for a moment, before the idea came to him.

"Don't kiss me back."

"Excuse me?"

"When I kiss you, don't kiss me back."

Remus scoffed, and his cheeks were perhaps a shade pinker than they had been a moment before. "All you kissing me will prove is that you're the one who's into guys."

Sirius shook his head. "Nah, because I'm doing it for scientific purposes only. Plus, I've already thoroughly proven that I like girls."

"You can like both boys and girls, you know," Remus said, raising an eyebrow.

"I know that, Moony. I'm not an idiot. But obviously I don't like boys, because I've only gone around snogging girls."

Remus rolled his eyes. "Whatever, Padfoot."

Sirius hummed. "So prove it then. Prove you're not gay by not kissing me back."

Remus sighed. "That wouldn't prove anything anyways. All me not kissing you back would prove is that I don't like you in that way."

"So you do like boys!" Sirius exclaimed, throwing his arms in the air in victory.

"No." Remus looked him straight in the eyes.

Sirius frowned. He scooted closer, so their faces were mere centimeters apart.

"What are you doing, Sirius?" Remus's voice was low, and his eyes glanced towards Sirius's lips involuntarily. He looked apprehensive.

Sirius's eyes were glued to Remus's. "Making you prove it!" he said, then put his hand around the back of Remus's head, quickly pulling him towards him, his lips crashing into his.

Sirius, as an experienced kisser, knew exactly what to do, and Remus was still for only a moment before his own lips started to react in turn and his body took over. He found himself kissing the black haired boy back with ferocity, and hardly knowing what he was doing, he wrapped his arms around Sirius and pushed into him, climbing onto his lap and straddling him, his fingers tangling in his hair and his body reacting in ways he'd never thought imaginable.

Sirius, the boy below, breathed Remus in as he kissed the boy who had recently haunted his dreams. Not that he could even remember those dreams, but something felt familiar as his tongue met Remus's and his teeth gently bit his lower lip.

Finally, finally, their lips broke, and they were both breathing heavy, brown eyes meeting gray. Remus didn't move from Sirius's lap.

"You know, I think I was wrong, Moony."

Remus snorted, confused. "Wrong about what, Padfoot?"

"I am definitely, definitely, very very gay. Or bi, or whatever."

Remus laughed, licking his lips. "Oh yeah?"

Sirius nodded. "One hundred percent."

"Prove it then."