Working under Carl Grissom, Napier sought control of Gotham City's criminal underworld, while also sleeping with Grissom's mistress, Alicia Hunt. Grissom caught wind of this, and moved for Napier's downfall, setting him up to be caught by the police at Axis Chemicals.
During the firefight, Batman arrived to aid the police force, beating Napier's goons, before accidentally dropping Napier into a vat of toxic waste.
Napier survived, though with extensive damage to his body, requiring a plastic surgeon. When he finally saw what he had become, Napier snapped. He sought out Grissom, killed him in revenge, and The Joker was now the head of crime in Gotham.
Napier is believed to have been a fan of King Partyman.