Ward, J. R., 1969- Black dagger brotherhood series

Series numeration from www.goodreads.com

"Nalla, the blooded daughter of Zsadist, has led a sheltered life. Protected by her father and the Brotherhood, kept away from the deadly war with the Lessening Society, she is chafing against the walls of the very safety that has ensured her survival. One night, she gives in to her restlessness...and finds herself face-to-face with a male whose inner darkness rivals even that of her sire's horrific origins. Nate is a fighter with nothing to lose--and nothing to live for. Tortured in a human lab as a young, then cursed with immortality, he is all vengeance and no purpose because he cares for no one--not even himself. The Brotherhood knows this all too well and following Nate's deliberate violation of the cardinal rule in the war, they declare him a dangerous liability that must be dealt with." -- from amazon.com