Hey Finn!
I have Ariel Sherington in Gryffindor for Leo Lupin and a third year slytherin UCPB Morgan Valenduris who shares a dorm with Serpentine Malfoy who.... is listed as an enemy on your spreadsheet? I think she's part of Serp's posse? I haven't any concrete ideas but I suppose theres a potential for drama or interhouse conflict? If he's animal torturer he may run afoul of second year Caroline Weasley who has animals as her Special Interest.

I also have Maeve Halloran who is a 5th year WC girl interested in wandlore for Billie Farrow and has lived around the Slums/High street her whole life so they may have a relationship that extends outside of Hogwarts growing up. So that's fun for you.

Greta Gillenwater is still a yearmate for Billie and the little sister of Cam (RIP - We found out via the paper.); she's been jealous of Anne and Ned's sibling relationship for most of her time at Hogwarts because Cam and her aren't that close and Ned is sort of the brother she wishes that Cam would've been - responsible and brotherly. That's going...... to be fun to emotionally deal with when I cross that bridge of morning yay.