Cas Crowfeather is my personal favourite character.  She's a red-headed French-Canadian with a fantastic dress sense. 

 

Cas is a talented young witch who is everyone's friend and is always willing to help.  But she does know where the limits lie and isn't afraid to insist on her point when she feels strongly about it.

 

She meets Milly very early on: they are room-mates.  They are also classmates in most of their lessons, and hang out together after lectures finish.  Cas peppers her magic with knowledge of her Native Indian roots - she can offer up traditional chants and knows just what to do with her dreamcatcher.  She is always there for Milly to talk to, and always tries to do what's best.