Traitor To The Blood by Barb Hendee
Born a half-breed to an elven mother and human father, Leesil was raised in the Warlands as an assassin, spy, and slave for Lord Darmouth, ruler of an independent province. But Leesil's mother trained him well, and he used his skills to escape, leaving his parents to suffer Darmouth's wrath for all such traitors and their kin. Now with newfound purpose in the company of his beloved Magiere, Leesil returns to confront the sins of his past and uncover his parents' fate.
Unable to turn him from this dangerous course, Magiere follows Leesil into the darkness of his past in the Warlands. Knowing what may happen should Darmouth learn of Leesil's return, she is prepared to slaughter any who try to take him from her. But Magiere's own past may well pose a more deadly threat. Two creatures of unfathomable power continue to stalk her - one who believes she's the key to his salvation, and one who seeks to destroy her ... and all those she loves.