Lover Eternal by J.R. Ward

In the shadows of the night in Caldwell, New York, there’s a deadly war raging between vampires and their slayers. And there exists a secret band of brothers like no other - six vampire warriors, defenders of their race. Possessed by a deadly beast, Rhage is the most dangerous of the Black Dagger Brotherhood...

Within the brotherhood, Rhage is the vampire with the strongest appetite. He's the best fighter, the quickest to act on his impulses, and the most voracious lover-for inside him burns a ferocious curse cast by the Scribe Virgin.

Possessed by this dark side, Rhage fears the times when his inner dragon is unleashed, making him a danger to everyone around him. When Mary Luce is unwittingly thrown into the vampire world, she must rely on Rhage's protection. Knowing that Mary feels the same intense animal attraction, Rhage must make her his alone...