The Paloma mermaids and Corbeau tree dancers have been feuding the entire lives of teen protagonists Lace Paloma and Cluck Corbeau. They've each been raised with tales of the other family's efforts to sabotage them, including claims of rape and murder, along with magical curses. There is magic in both families; the mermaid women have scales on their backs, and all the Corbeaus grow feathers from their scalps.
McLemore may be counting on most of her readers to know at least a little French and/or Spanish, but just in case you don't she slowly helps you out with the symbolism of the family names. Paloma means dove in Spanish, and Corbeau is French for crow. Lace's father's last name was Cuervo (crow) before he joined the family, which I think is pushing the connection too hard.
Anyway, Lace and Cluck are likable characters with sympathetic struggles.