The description that Ravus gives of his mother to Val seems to fit more of a huldra than a traditional troll. Huldras are usually depicted as beautiful with a penchant for human men, and are very good to their husbands until they do something that makes them so angry, they kill them (which Ravus' mother could have done, and just told Ravus and his siblings that their father just "wasn't coming back," or just let them believe that he really did only run off). They are also confused with or considered trolls or a sub-species of troll in Scandinavian/Nordic folklore, so it would make sense that that is what she was called. The only thing that doesn't quite fit is that huldras have tails (which Ravus doesn't have), and when a huldra marries a human man, she becomes ugly (which she never did). However, this could be explained by Gender Equals Breed (and since "troll blood breeds true," it went Female=Huldra, Male=Troll), and that Ravus' parents were never married.
- I kind of like this WMG but when Ravus said his mother was beautiful he also added that his idea of beauty is more open than Val's. So his mother might not have been beautiful for general faerie (or even human) standards but for troll standards she was probably considered hot. But I do like the idea that Ravus' mom killed his dad rather than him just never returning, because he does say when they love they are all love, so when they're angry they're all anger.
- This makes sense to me. It does fit with the fact that Ravus mentioned that he grew up in Iceland, and his lack of a tail could possibly be artistic license on Black's part.