Who is Rita Ritter from The Persian Pickle Club and what is their importance?

Rita is the novel's primary antagonist, a character who comes into a comfortable and established situation and creates conflict by being different and by forcefully pursuing her intentions. She simply does not fit, does not really want to fit, and does not really try to, either. She is outspoken and impulsive, Rita's presence is a challenge and something of a trial to the members of the Persian Pickle Club, who nonetheless accept her because she is related to two of its members.