Darkness Forbidden (Book 1 The Dark Intentions Trilogy) By Author J. M. Rankin

Immortal, ruthless, cunning...
Obsessed with his haunting and depraved bloodlust, Alex Demeter finds himself intrigued by Catrina, a human with a past she cannot escape.
Disturbed by his distraction, his eternal partner Nadia wagers the ultimate prize: the one thing Alex could never have.
But after nearly five hundred years, Alex knows Nadia far too well to think she'd ever play fair. As he's forced to face horrific truths from his tormented past, the humans around him soon find themselves pawns in a game they could never understand...