Sirius made a horrible face at the mention of Severus. He didn't even want to begin thinking about chumming around with him. The greasiness might be contagious or something. Merlin only knew when the last time Snievellus'd had a bath was.
"I chase away peace and quiet?" Sirius asked, feigning innocence as he put a hand to his chest. "Me? Surely you've got the wrong bloke, Moony." Knowing Remus wasn't going to fall for that, Sirius shrugged. "Entertain me. I'm dead bored, mate."
And it was either chat with Remus or go find some dark corner of the astronomy tower to sulk in.