Who is Oliver from Masquerade: A Blue Bloods Novel and what is their importance?

Oliver Hazard Perry is the best friend and human Conduit of Schuyler Van Alen. He is in love with her, and takes care of her. The two frequently hang out and travel around together. When Oliver discovers that Schuyler needs a human familiar, he volunteers twice to do so, backing out the first time because he doesn't believe Schuyler is being forthright.