He grins, and starts concocting nefarious plans. Because nefarious plans concocted at breakfast are clearly the best nefarious plans.
He smiles at her again.
"Although I'd probably have come up with something like that eventually anyway so I guess I can take all the blame if you want."
"I'm sure there's some Freudian explanation but I have no idea what it is. Hm, well, thinking about it it may have something to do with the years of bullying and the defence mechanisms created, where I'd become scarier than the bullies were and more frustrating than their other targets until they either gave up or something bad like the Hulk incident happened. I mean, I don't want to cause trouble per se, I just think it's funny to be a wild card and I really really dislike bullies."
"There was this one time this bully was, well, bullying me, calling me freak and he-she and other worse stuff, but he pushed some very specific buttons he was not supposed to know about, and I was not quite able to not, erm, morph into something very scary and then hit him a lot." He doesn't blush, but he looks suitably embarrassed. "That's the one time I'm very certain the Ministry actually erased a lot of time from the minds of a lot of people. And, er, that won't happen again, promise. I don't, er, have temper problems anymore."
"I'm not sure why this all adds up to deliberately making room in your schedule to provoke people."
He happens to catch said Slytherin's eye just then and waves at the boy, who scowls and returns to his conversation.
"Yeah, I do. And I usually try to offset that by being extra-nice to other random people. This has helped before! Not as much as I'd like, but yeah."
"I think this might just make you seem weird and inconsistent and constantly up to something."
"Mmm, I don't think I'm inconsistent. I can consistently predict the kinds of stuff I'm going to do, usually! Like, I think if someone had told me beforehand that Rufus would mention my parents' situation to me I would probably have noticed this would make me unreasonably angry and then taken steps to prevent myself from being angry. The surprise was a decisive factor, there. And I can totally predict that I will sometimes tongue-flick at random people just to watch them go 'eep.'"
"I didn't think it was, but it sounds inconvenient to me, especially if you ever want to have more friends than the three of us."
He laughs. "Besides, I can totally get more friends. I predict Jacob and I will become friends byyyyyy the end of the year. Jacob's another firstie Slytherin, by the way."
"Ooh he might just be! I was wondering how you'd found out. Oh man he is in so much trouble, I'd better help him out. Tentative prediction change: friends before the winter holidays."