Insatiable by Shannon West

Vampire Slayer Valen Beauchamp has an old score to settle with Julian Montague. It all started in the year 1733, when Valen narrowly survives an attack by centuries old vampire Julian Montague, and even receives a minor bite when Julian’s teeth scrapes his skin before he manages to get away. The venom from the bite almost kills him, and he soon discovers that Julian is searching for him everywhere to either finish what he’d started or kill him outright. Neither option is attractive to Valen, so he flees to the New World. As time passes and he doesn’t age, however, he comes to realize that the vampire had perhaps not destroyed him, but instead cursed him with an unwanted gift—immortality.
When he learns that victims of deadly vampire attacks are dying in large numbers in Paris, Julian’s home, Valen decides he’s tired of hiding from monsters and travels back to Paris to use his formidable Slayer skills to end this thing once and for all. During a tense confrontation in the dark cellar of an opera house, Valen finds himself mesmerized, overpowered and seduced by Julian and finally succumbs to his charms. And even that wouldn’t be so bad if every vampire slayer in Europe weren’t out now to kill them both. Valen is falling deeper and deeper in love with the vampire while trying to figure out if the vampire who bit him is one of the good guys or not, and if their love will mean his ultimate damnation or his salvation.