Dark Passages: Tristan & Karen (The Brethren #4)

Tristan Morin is a vampire on a mission: to not fall in love with Karen Pierce. To do so would prove that humans and Brethren were meant to be physically and emotionally bound to each other -- something he, as a full-blooded Brethren, refuses to believe. It would be so much easier if Karen wasn't beautiful. And if there wasn't something about her that draws him like a moth to a flame, damn near impossible to resist. Karen has always felt an inexplicable attraction to Tristan. More than just the fact he's strikingly handsome, it's as if being with him is something natural, comfortable and right. But soon a brash choice on his part leaves her heartbroken and confused, and a sadistic new enemy will put their newfound love -- and their lives -- to the ultimate test.