Andrea's Overlord by Michelle Marquis
Life has not been kind to Andrea Quill. Born in a world where vampires breed humans for pleasure, she has the bad luck to be smart and independent. Unfortunately, those are qualities that get humans killed. When Andrea is pledged to her first master things look even grimmer for her. That is until she is forced to spend her first night with vampire assassin Mikel Hellborne. Mikel Hellborne has the best of both worlds. He is both a vampire overlord and an assassin. But when he meets the strong-willed Andrea even this jaded overlord can't let the rebellious beauty die.