Touch of Darkness by Christina Dodd

Handsome, powerful Rurik Wilder battles darkness -- the darkness without, and the darkness within. For he possesses the power to transform himself into a fierce bird of prey, and that gift has caused death and destruction. At last he is offered the chance to redeem himself and break the evil pact which has held his family in thrall for centuries. Only one woman stands in his way -- flamboyant Tasya Hunnicutt, a writer determined to wreak revenge on the assassins who murdered her family. Assassins, it's been rumored, who have powers no human should ever possess...