As Gotham marches to its series finale later this spring, the show recently dropped a major bombshell in the evolution of Batman archvillain the Joker. As an origin story for DC’s Dark Knight, the name “the Joker” has never been mentioned on the show, but Gotham nonetheless features earlier versions of the villain in the forms of Jerome and Jeremiah Valeska. Both characters were played by actor Cameron Monaghan and share some of the Clown Prince of Crime’s penchant for criminal insanity. Before his death in season four, Jerome Valeska had his face surgically removed and then reattached, similar to what the Joker did in the modern classic Death of the Family storyline.

Jeremiah Valeska, the show’s second iteration of the character, also took many elements from the Joker that fans are familiar with, including the villain’s iconic pale skin and affinity for poison gas. The show took Jeremiah’s evolution as the Joker an additional step in the most recent episode, which was entitled “Ace Chemicals.” At the climax of the episode, Bruce and Jeremiah are seen grappling on a catwalk. In the scuffle, Jeremiah falls into a vat of green chemicals. The scene seemed to be inspired by Tim Burton’s Batman from 1989, which also showed the character falling into a vat of acid. “Ace Chemicals” ends with Jeremiah barely alive, having lost all brain activity following the accident.

Monaghan teased the final evolution of his character into the Joker in an interview given prior to the season premiere. In the interview, Monaghan discussed the difficulty of bringing both Jerome and Jeremiah to life. Elaborating, Monaghan noted how Jerome’s arc was incredibly intense. The actor played Jerome from season one to midway through season four. Following Jerome’s death, Monaghan began playing Jeremiah, who had his own distinct personality and objectives. As the show’s fans await the final iteration of Monaghan’s character, Gotham showrunner John Stephen remained coy on whether the show would actually refer to the character as “the Joker.” Nevertheless, in an interview with TV Guide, Stephen did hint that the next version of Monaghan’s character would be an amalgamation of both Jerome and Jeremiah.

Gotham airs on Fox each Thursday.