Okay so first thought is Clair Sauvage. Ravenclaw sixth year. He's a jerk, a bully and used to get into physical fights a lot when he was younger. Has really abrupt mood swings.
He's only ever really nice to Charlotte Waldorf and that kinda comes of him being subconsciously sexist. He's kinda friends with Margo Richards, and he has a crush on Julian Kapur, but he isn't really
pleasant to either of them, if that gives you an idea of his personality.
Lilith Llewellyn is only a third year, but she's a pretty obvious blood supremacist. She's basically brainwashed, and is out to brainwash other people. She's a dark follower. She's also open for pretty much anything. If Alva wants to try to persuade her she's wrong, or dob her into the teachers, that's all good.
I have a couple of other students - Darcy Driscoll is a second year Ravenclaw, Christian Thorfinn is a second year Slytherin and Selwyn's brother, and Bethany Dursley is a fifth year Ravenclaw - but I don't really see any immediate opportunities for them.
And then I have Selwyn, Destrey and Angelique.
Selwyn's the Deputy Headmaster and tries to be strict but fair. Usually he just ends up making people resent him. He has an open class thread
hereDestrey Ashcroft is the Defence teacher and likes using her students for practical demonstrations.
Angelique Pyrites is the school healer, and a dark witch. She helps the Death Eaters sometimes. Her main thing is deliberately giving students sub-standard care for kicks, so if Alva's ever had a quidditch injury, she's probably enjoyed that.