Ward Against Destruction — Melanie Card

His love will give them life or destroy them. Ward de'Ath used to think that nothing could be more terrible than death. Now he realizes there are worse things. Like his never-ending hunger for blood. Even if he conquers the unbearable cravings that drive him headlong toward destruction, he's a wanted man with a bleak future. Assassin Celia Carlyle learns she is the only one who can protect Ward from disaster. She loves him-she wants to help him, but no one can tell her how to save him from himself. And the confusing voices in her head scream to let him go. But Ward's dark trials keep mounting. A malevolent evil is rising in the land, threatening to unleash horror upon the world. The only way Ward can defeat it, and have the chance to marry Celia, is by accepting his fate and becoming the one thing he swore he would never become...