Hammer with his brother Sickle called were born as conjoined twins. Their father left them at circus, where they were raised as bruisers. Joker and Harley Quinn wanted them in their own gang. However, Joker wanted them separated, so Joker hired Dr. Thomas Elliot to perform the operation. After operation Joker keep Mr. Hammer and left Sickle at the Iceberg Lounge as a gift for the Penguin.