Who is Richard Rigel from Lila: An Inquiry Into Morals and what is their importance?

Richard Rigel and Phaedrus meet in Oswego, but they really get to know each other in Kingston. The morning after Phaedrus's night with Lila, the two men discuss whether or not Lila has Quality. Rigel also warns Phaedrus about Lila's mental condition. Rigel, a successful lawyer, has known Lila since they were children.