Well hi, it's been quite a while. This is naught but a taster of what is to come (hopefully), so hang in there and you may see more.
Disclaimer: I own nothing; this is mere fiction based around characters created by JK Rowling.
Lolling back in his chair, Sirius flung both arms behind his back and, hands joined, pushed them out in a stretch so satisfying that he let out a small groan. Although nobody else seemed to hear him over McGonagall's explanation of a new spell, he saw from the corner of his vision the involuntary flicker of an adjacent Remus' eyes towards him. Allowing what he very well knew to be his very most dashing smirk to glide onto his face, Sirius felt a little ball of satisfaction bloom in the centre of his chest. It was only when he noted a cough and a subtle shift from the brown-haired boy beside him that Sirius ripped a small piece from the corner of his parchment and scrawled out a note in handwriting which managed to look both refined and elegant despite his speed.
He slid it sideways towards Remus, trying not to be noticed as he watched carefully for any kind of reaction from the werewolf.
'Are you going to be off studying like a prat tonight, or are you going to join us for a bit of fun?' read the note. A small furrow showed between Remus' eyebrows –doubtless at the part about him being a prat– but his face otherwise remained relatively free of expression, meaning that Sirius was forced to wait and see what Remus scribbled by way of messy reply.
'Who's "us"? And that depends what kind of fun. If it's an orgy, you can count me out.' The barely-repressed grin on Remus' face showed how clever he thought he was being. He was lucky that Sirius was used to humouring him.
Reading this response, Sirius shot Remus a look that was meant to convey a strong sense of disappointment at his lack of trust, and to plead him to grow up. Probably though, this meaning wasn't properly conveyed, as Remus chose to ignore him in favour of jotting down something or other McGonagall had said may or may not be important to know for their NEWTS. Which were over a year away, so Sirius saw no point in listening now. He knew he'd get O for everything anyway, he always did. Tearing himself away from thoughts about these slightly less-than-imminent exams, Sirius picked his quill back up and wrote out his reply.
'Us is the same us as always. And fun is... Fun. More enjoyable and less dusty than books. You should try it.' Sirius' face now turned to a carefully calculated look which kept just the right balance between innocence and casual disinterest.
'Fine. If you insist upon wrecking my education. May it be on your conscience.'
As Remus passed over this latest scrap of parchment, Sirius had to hold back a crafty little grin. All was –as yet– going according to his vague inkling of a plan. Perfect. He leaned luxuriously back in his chair, stretching his arms over his head, pleased by the way Remus' Adam's apple bobbed up and down as he looked at the newly-exposed strip of pale skin above the low waistband of Sirius' trousers. Yes, all was currently going well.