From Protector of the Grey House:
He ground his teeth, closed his eyes, and squeezed his fists tighter. It was becoming increasingly difficult not to throw her down on the floor and have his way with her. He just didn’t have the time. “I leave tonight and stay no more than three nights.”
Natalia reached out and caressed his closed fist. He opened his eyes when he heard her gasp. “What did you do?”
Surprised by her question, he looked down at his now open hand. There were four half circles of crimson on his palm. Blood pooled in the shallow of his palm, and ran down the sides of his hand. He hadn’t even felt it. Vincent opened his other fist and saw a similar scene. He frowned into Natalia’s eyes. Her eyes were clouded and dreamy, as if drugged. He almost asked what had transpired between her and Diana when Natalia brought his hand to her mouth and licked his hand clean. Once the tiny pool was gone, she sucked on his hand. Vincent growled, closed his wounds, and gave her his other palm to clean.