histórias de Witchesfamiliars

Bran Cornick hates witches. Not only are witches and werewolves often enemies, but witches always seem to target him and his family. So what does it mean when a witch saves Bran's son, despite knowing who and what they are? How does she have so much power if she's not a black witch? And why does Bran's wolf say that this witch is his mate?