Trolls have a longstanding animosity for goats--"Who's that trip-tapping across my bridge!?"--and this led me to think that perhaps trolls are related to goats, since it seems a lot more plausible to me that your relatives would make you insane than some random hooved mammal, however ecologically destructive it might be. What if trolls evolved from goats? Or, no, better yet, what if goats evolved from trolls? Or were domesticated from trolls by human shepherds? And the trolls despise their domesticated cousins as a disgrace to the once-proud troll race, (much as I assume wolves would despise Chihuahuas if they ever gave them much thought) and eat them at every opportunity.