Who is Arcangel from Tropic of Orange: A Novel and what is their importance?

Like Manzanar, Arcangel is an unknowable character, but Arcangel is even more mysterious. He seems to appear out of nowhere yet has a history that stretches far into the past. At times Arcangel claims that this history stretches back hundreds of years, but the reader cannot know if these statements are to be taken literally or if Arcangel is making figurative statements to explain his cultural heritage.