Blood Bound is the second of the Mercy Thompson series. Mercy is a woman with a problem, namely two werewolves, Samuel the very dominant lone wolf who used to be the love of her teen life, and Adam, alpha of the local pack. Samuel is the son of the Marrok, the over all leader of the weres. In Brigg's universe, the weres are very long lived as well. Samuel is centuries older than Mercy and has lost all of his children. He believes that Mercy and he could have ones that live because she's a Walker, a preternatural being that we don't know much about yet other than she turns into a coyote. He's living in her trailer, temporarily, working as a doctor at a local hospital. Adam lives next door and had previously claimed her as his mate so the pack would leave her alone. Now they've gone on dates and she might love him but is definitely not in love with the misogyny of a wolf pack.

As if this wasn't complicated enough, the book opens with Stefan, the vampire (who wins for owning a VW van decked out to look like the Mystery Machine), asks for a favor. Walkers are mostly immune to vampire mind tricks so he wants Mercy to go meet a vampire encroaching on his Mistress's territory but he wants her to go as a coyote. Much to everyone's horror, it goes terrible wrong. Mercy is badly hurt and Stefan may have killed some innocents.

Shocking everyone, they learn that is was a sorcerer (in this universe, a human who's sold his soul to a demon) turned vampire. The fact he could subvert Stefan's mind, Stefan being stronger and older than most vampires, means they're all in trouble. Mercy is sidelined so she can heal while the vampires and the werewolves reluctantly team up but it may be more than they can handle. Mercy is in danger of losing her pack and is reminded that vampires are more or less evil, even if Stefan is less evil than most. There is a lot of world building for the vampires in this one.

Overall, I thought it was very enjoyable. I like Mercy and her friends. The obvious romantic triangle might be a problem for some people. Like many UF heroines, Mercy has a lot of men after her, unlike others, though, this makes more sense. Samuel is a reminder of her youth, Adam is the alpha and well I'm not sure Stefan counts. I don't mind the triangle (though I do like Samuel more than Adam).