Fan Casting Harley Quinn in Batman: Arkham Asylum

Whilst Batman was escorting the Joker through the Intensive Care unit of Arkham Asylum, Harley was already in the security control room. As the Joker broke free, she opened the adjacent security field allowing him to escape Batman and implement his takeover of Arkham. Harley then took Warden Quincy Sharp hostage, taking possession of his decorative cane as well as wearing his warden identification card, and contacted Batman via monitor. She claimed that the Joker was now in charge of the island and she was substituting for Sharp as warden. She also told Batman that Joker was having a homecoming party with Batman as the guest of honor.