William Hayes murdered his younger sister, Greta, in order to become "pure evil". He did this in order to become worthy of wielding the Sword of Beowulf, an ancient weapon he subsequently stole from a museum. Overhearing the incantation to activate the weapon's powers, he speaks it, quickly killing a room full of police officers and the museum curator, taking the name of "Harm". Later the same night, he notices Artemis and Zatanna fighting crime around the city. Eventually, he confronts the two, pursuing them until they happen upon Harm's own house.

Knocking the two unconscious, he questions Artemis on how they had found his home. She remarks that his partner led them there, only for him to say he had no partner. Zatanna and Artemis eventually free themselves, running into the backyard to discover his sister Greta's grave. He remarks about how she was the only person he loved, and that by killing her he could become "pure". Her spirit appears before him and removes the "purity" from his body, therefore making him unworthy of using the sword. After being disarmed, he attempts to strike at her, only for his attacks to pass through her body. He is then defeated by Artemis.