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

Emi is the most jaded and cynical of all the characters. However, this cold persona may be on the surface only. At least one other character believes that the true Emi is a warm, caring, and generous person. A few hints of Emi's caring nature surface during the novel, such as her concern for Gabriel and her taking time to find batteries for Buzzworm, but for the most part Emi comes across as a thoroughly modern and thoroughly world-weary, Angeleno, or native of Los Angeles.