Joker ended with Arthur having fully transitioned from a man who felt society let him down to the villain known as the Joker. With a major part of Arthur's arc complete, Joker: Folie à Deux might bring him along for the ride that will be Gaga's Harleen Quinzel discovering her inner Harley Quinn. From the Joker: Folie à Deux Harley Quinn set photos and videos that have been revealed, Gaga seems to be trailing the same path in the sequel that Phoenix did in Joker.