Of course, that's part of why he's doing it.

If anyone - James or Peter or, Merlin forbid, Remus - were to catch him here, like this, he'd be in a well of humiliation, not to mention the fact that everyone, once they stopped laughing, blushing and saying absolutely nothing at all before walking off (respectively), would demand some sort of explanation.

And the honest answer, which, given the situation, is really the only answer he has any right to give, is really not something he wants to get into right now. His mind smirks at the pun and he ignores it, deciding that innuendo and punning are really horrible habits that he needs to rid his life of especially if he's going to continue doing this.

This.

His heart pounds louder, loud enough that he imagines that anyone down in the common room must surely be able to hear it, as he slips behind the curtains, pulling them shut tightly behind him so that absolutely no light can penetrate the darkness.

Oi. Penetrate. He really, really, really needs to stop that.

The thought doesn't hold long though, as the lack of light settles around him in a sort of musty dimness rather than pure black. He closes his eyes and takes a deep breath and his heart picks up a new, additional beat that is better than the fact that it could be skipping like some sort of lovesick girl's.

The air smells like Moony. It's raw and rangy and moist and thick and wild and like the iron heat of his control. It's musty and damp like any enclosed teenage boys bed and it makes him ache in places he's never ached as strongly before. His cock strains against his pants and he nearly moans aloud, catching the sound even though he knows no one can hear.

His head provides vivid pictures of Remus sprawled naked on this bed, cock in hand, head tilted back so that the sun-spattered brown of his hair is splayed out over his pillow. He sees the arched back and the taut muscles straining against flesh and bone and his hand is moving, fast and hard and he's panting and licking his lips and his feet are thrashing slightly, pajama pants around his ankles, tangling in stripes as he gasps helplessly, come spilling on his skin.

Sirius groans, unable to help himself this time. He falls back on the bed, his own dark hair haloed around him as he takes far too much time to unfasten his slacks, too long to get his hand against his cock. He huffs out a sound that's half relief and half need, the dampness of his palms negligible against the heat of his shaft.

He turns his head and uses his free hand to push the pillow against his face, burying it in the smell of Remus. His other hand moves franticly, furiously. Getting caught is no longer a concern, only getting off. He releases the pillow and uses his hand to push his slacks down farther until they're tight around his thighs and he can wrap his fingers around the base of his cock, holding it as he focuses his attention on the liquid touched head.

His eyelashes flutter on his cheeks and all he can see is Remus. He's memorized him in ways that would make James jealous, Peter flustered and Remus… He gets no farther, rational thought giving way to the sight of him in the shower, stripping off his clothes after they'd gotten caught in the downpour. Towels and dirt and water dripping off his thin frame as he'd shaken his head, not looking at Sirius's blatant stare.

Hot need lances though him, making his hand move faster, harder. He's gasping, beyond the realm of any semblance of control. Tight nights in the corridor underneath James's far too small cloak, whispered breath for secrecy that fuels nights of fantasy in his own bed, his own smell surrounding him as he imagines the feel and taste and scent of Remus until he comes.

Sirius groans again, feeling the pressure of his orgasm against the fingers pressing hard to his skin. He wants to stave it off, prolong it, even though every second brings him closer to getting caught. His cock surges and he imagines Remus's eyes, unfathomable and inflamed, watching him as he comes. Sirius shakes his head, his throat too thick with desire for air, his lungs aching as badly as his cock as he finally gives in, his heels digging into the mattress as his body stiffens, tightens then releases, his orgasm spilling hotly around him.

He is never going to be a mastermind. Peter resigned himself to that fact long ago, long before he met Remus and Sirius and James. No, he thinks to himself as he hurries away, small claws slipping on the polished wood of the tower floors, sliding on the slick surface, he will never be a mastermind.

But. He looks around the dark room, assuring himself he's alone before he transforms, shaking off his rat visage as he slips to human again. But masterminds need minions and Peter is nothing if not a good minion.

A minion with information that, even if he isn't sure what exactly it means - other than the fact that Black is even more of a traitor to his blood than Malfoy had originally thought - he knows it means something.

And, like anything that means something, it'll be worth something tangible to someone. Peter serves many masters, all of who might be interested in the knowledge - James, Remus, Malfoy, Snape, Voldemort. Yes, worth something tangible to someone. The trick, and he laughs at the word and its meaning, is simply knowing who.