Yes, it is rather like your Nobilis character - Sirius is definitely a Power.

:-)   Pyanfar and Jik make an interesting friendship. And in fact Py is still very much married and devoted to her husband, Khym Manh, so it really is a virtual-sibling female-male type friendship, of the sort that is all too rare in fiction. And I'm just busting your chops about remembering the book, but it is one of those very, very important books to me.