Jack was a metahuman whose body's cell structure allowed him to be entirely elastic. Like the other members of the Royal Flush Gang, he was taken from his family by the U.S. government and educated at Project Cadmus's secret facility in the Arizona desert. The government's original plan was to use him and the other children as human weapons, before they were liberated by the Joker. Free of their captors, and encouraged by their new mentor to use their powers for mayhem, the kids happily became his new henchmen. Jack in particular said that he liked Joker's "style".