Sean Glenanne is the older brother of Fiona. He and Michael Westen first met when Westen was posing as IRA member Michael McBride. Westen never informed Sean of his real identity. He later enlisted McBride to help him protect his little sister from an Irish radical named Thomas O'Neill. Fiona never told him that Michael was not truly Irish, as Fiona claims that "Sean can never know" or else he would never forgive her.