Bad Blood — Mari Mancusi

Sunny McDonald is in the ultimate forbidden relationship. Her boyfriend Magnus is a vampire, and the leader of the Blood Coven. And when the Coven decides that Magnus needs a mate to be his co-ruler, Sunny's humanity puts her out of the running. The Coven's chosen candidate is Jane Johnson, a magna cum laude graduate of Oxford University who just happens to look like a vampiric supermodel.

Sunny is suspicious of a Rhodes Scholar who can't answer the most basic poli-sci questions, but Magnus brushes it off as petty jealousy. Still, when the Blood Coven goes to Las Vegas for a vampire convention, Sunny and her twin sister Rayne secretly tag along. And Sunny's not going home before she learns the truth about Jane. Because not everything stays in Vegas-especially bad blood.