(You know, I was always kind of disappointed that Caster wasn't an option as she was one of the best characters in my opinion.)
They were planning a route with her, IIRC, but it had to be cut for some reason.
Funnily enough, in FHA, Caster notes that Shirou & Souichirou are pretty similar when she and Shirou are discussing something. And Shirou is one of the few who can tease Caster and get away with it.
