From The Grey House, Book One:
Natalia grunted as he bit. His fangs pierced her flesh close to the elbow. She stopped herself from pulling her arm away. She trusted Tony more when he took her blood. For Tony, it was payment; for Vincent, it was something more and that made Natalia nervous. Natalia held her arm still and felt when he withdrew his fangs. He sucked at her arm, her blood, and the pain did not diminish. Natalia waited for the vampire to be done, wondering if she made the right decision. She knew it would always be this way, would always hurt. The thought made her understand she would probably allow this to happen again. She wasn’t yet sure how she felt about that.