OMGZ ANOTHER TWIN. Ella loves him for being a twin, and also because he's pretty, she probably ignores all his flaws just because HE'S A TWIN.

Since Frankie is dating a girl she probably would not get on with Leon, even if she is a bookworm and they're in the same house. She's a very liberal person and wouldn't tolerate any homophobia.

Mari doesn't really hold any loyalty towards anyone when there's a hot boy in the midst. She'd probably tease him a lot if she ever hung out with him. Also they have England in common.

Charlie is in the same year but I don't know if they would be friends. Charlie is pretty laid back and stoned all the time so Leon might mistake that for being stupid xD However, on the other hand they could be good friends. Also Charlie can get Leon any drugs he wants. JUS SAYIN'.

As for Sim, I can see him getting along with Leon, mostly for theinteresting fact of his budding drug habit. Sim has been there and doesn't really want to recover, I can see him leading Leon onto bigger and better (and worse) things.