I think you've got a perfect boy's teenage voice, and especially a perfect Sirius voice here - rebellion, just "For the Sport of It" at this stage, indeed. I also like the faint hint of surprise (almost slight condecension?;)) in But the thing was, Potter had turned out to be all right, and the sense of excitement and planning for the future as friends with similar thinking.

And, of course, I love Remus, looking on and wanting to be part of it all and them. See, just half a sentence, and I want to hug your Remus as usual. ;)