You have expertise in a specific field that makes your conversation intriguing to an older Kindred. So long as your knowledge holds the other vampire’s attention, he has a vested interest in keeping you around. Then again, once he’s pumped you for every iota of information you possess, that patronage may suddenly vanish. (Note: This Merit should be played like a 1-dot Mentor with a specific interest. However, unlike a Mentor, Useful Knowledge does not imply a permanent relationship.)