Joanna is one of the friends Marianne makes at college in Dublin. Unlike her other close friend, Peggy, Joanna takes Marianne’s side when she and Jamie break up, eventually revealing that she never really liked Peggy and Jamie in the first place. Joanna remains a supportive person in Marianne’s life, trying to help her make sense of her confusing relationship with Connell and, in a broader sense, generally staying by her side.