From The Grey House:
She opened her eyes. “These are used by Slayers. If you have them, they can’t be used against you and yours.”
He nodded in slight agreement. “What else?”
“Myself.”
He gave a slight laugh. “I expect payment to be one-sided Natalia. It’s not really payment if you extract pleasure from it. Try again.”
Natalia closed her eyes as she said one word. “Blood.”
Vincent stood and walked around to Natalia. She looked up at him, then took his offered hand. He sat on the edge of the desk and indicated she should too. Her face was masking her emotions. Humor was shining in his eyes.
“How much blood do you offer me and when can I expect it?”
“Some now; as much as you want when my friend is safe.”
He gave her a sly smile. “Sounds like an ideal plan. Leaves me in control, Natalia. Are you sure you want this?”
“If it means Bethany’s safety, yes.”
He traced the line of her jaw with his cool fingers, helping to relieve her pains. “So much pain, Natalia, for what? A human? Is she worth it? Would she do this for you?”
“No, but I wouldn’t expect her to.” Natalia’s determined look was back. “She doesn’t know what the world is really like.”