After Marty's death, Louise acts as a business associate and Vic's love interest during the game, although their relationship turns sour later on. Marty, angered by his wife's act of hostility, attempts to kidnap her but is ultimately killed by Victor. Early in the game, Louise resides in the a trailer park with Marty, but grows increasingly unhappy of her rocky relationship with Marty, eventually leaving his home, taking Mary-Beth along with her, and staying in Mary-Jo's apartment in Little Havana.
As implied from her family name, Louise is the sister of Phil and Mary-Jo Cassidy, the wife of Marty Jay Williams, the leader of a local gang (as mentioned by Phil, by way of Vic's pager), the mother of an infant Mary-Beth Williams, and Vic's love interest.
