Jack was a member of the third Royal Flush Gang. His specialty was knives. After Melanie left her family's life of crime, Jack took over as security systems expert, though he clearly wasn't as good as his sister. After the encounter with Batman forced the family to leave him behind, Jack spent a few days in prison before Melanie bailed him out with her restaurant paychecks. He gladly accepted her offer of washing the dishes at her workplace, claiming he was "the best dish washer in juvie hall."