After a successful career of finance, Christina Bell joined the board of directors at Queen Industries in Star City. During a blood transfusion following a miscarriage, Christina was exposed to the Joker's Titan-infected blood. When she returned to work, Christina took a knife to a board meeting, brutally murdered eleven senior executives, and carved smiles on her victims' faces. She adopted several facets of the Joker's personality, notably his obsession with Batman.