The situation with Catherine and her friend is definitely suspicious; a tracker in one girl and an attack by bandits against nobility - were there no guards? - makes me quite unsure that the people who are tracking her are even related to Catherine's family. We'll have to see but they won't get past her barriers anyway.
Someone banged a dog to make a half-fenrir race?
When it comes to gods and magical creatures that are physically very different from humans, breeding is usually done by magically transforming into a human.
Or maybe there was some sort of blood bond pact with actual mixing of blood and it just magically persists in their bloodline.
We'll have to wait for the explanation.