They're all a bit unstable Yanderes for you(all of them are girls)
Remilia: acts very ladylike, but is small and childish, master of the mansion, vampire
Sakuya: diligent and a bit cold, head maid of the mansion, can be found anywhere
Patchouli: Bookworm, doesn't talk to people much, very unhealthy(asthmatic), Librarian
Meiling: Lazy but diligent gatekeeper on the mansion, chinese girl
Flandre: very unstable, vampire, locked in the basement. Very shy and childish, but EXTREMELY unstable.
Koakuma