The Changeling's Oath

Caleb is a werewolf; except they aren't called werewolves. They're called changelings. How he became a changeling is just like how you'd expect, he was bitten by a changeling. If that wasn't bad enough, he learns that he's also the king of the changelings and there's a power-hungry vampire out there that just wants all of his kind dead. To matters worse, that power-hungry vampire happens to be his boyfriend's father.

Caleb is thrust into a world that not only did he not know existed, but also never believed could exist in the first place. With the help of boyfriend, Garrett, he manages to maintain his sanity. Now, along with learning how to control his wolf side, he has to figure out just who killed his parents, where his brother disappeared to, and who changed him.