From The Grey House:
Anthony was standing by a new vampire. Vincent searched for her name and remembered when he heard her laugh. Kari. He liked her well enough but was not sure where her loyalties lie. Anthony turned from her, saw Vincent watching and came toward him. Before he arrived, Vincent flagged down a waiter and asked for two glasses of his private stock. The waiter, a long-time employee, bowed and went off to do as he was told.
Anthony arrived before the waiter returned, so Vincent made light talk. When two goblets were presented to him, Vincent smiled and thanked the man, slipping him three twenties. Vincent believed strongly in rewarding loyalty.
Anthony smirked at the gesture, clinking goblets with his leader. “You pay them more than anyone else. Why tip them for wine?”
“It’s not wine.” Vincent stated between sips. The liquid held no sustenance; the taste was all he wanted.