News that Jared Leto will reprise the role of the Joker for Zack Snyder's Justice League came as a complete surprise, as the actor was reportedly finished with the role and had never been attached to the original film in the first place. Some fans are more excited about his reprisal than others, and even Snyder Cut diehards are wary of Leto's presence, with one of the most obvious reasons being how poorly received his performance was in Suicide Squad. Regardless of that, however, Leto is joining Justice League. The only question tis how he'll be used in the story.
The answer, most likely, is that Snyder will use the Joker to connect and tie up as many plot points as he can. Several Easter eggs and teases were planted in many of his previous DC films, intended to set up an overarching storyline extending from Man of Steel through Justice League and beyond. Ultimately, those threads were left unexplored, resulting in dead-end plot points that left fans with questions. It's likely that Snyder will utilize the character of the Joker to tie up many of these loose ends, thus resulting in the end of his DC Extended Universe story.
It makes sense that, given an unprecedented opportunity, Snyder would want to tie up as many dangling plot threads from his DC films as possible. That includes the Joker's murder of Robin, which was referenced in Batman v Superman: Dawn of Justice with the Easter Egg of a vandalized Robin suit in the Batcave. Snyder has clarified the identity of the late Robin was Dick Grayson, and he's also said that a hint at how his death occurred would have been part of his version of Justice League. With that in mind, it makes sense that Leto would be involved in the reshoots that have included Ben Affleck's Batman.
Leto's scenes could involve a flashback to Robin's death, as well as its aftermath. It would offer Snyder a chance to delve deeper into the trauma that made his Batman the grizzled veteran he is. It also gives him a chance to pay off the mystery of the Batman vs. Superman Easter egg, rewarding the people who championed the release of his cut of the film with some fan service.
Leto's Joker could also be involved in tying up another Batman vs. Superman Easter egg: the Knightmare sequence. Batman's vision of a post apocalyptic future was one of the most memorable parts of Snyder's DC work. Fans have speculated that the Joker card taped to the butt of Knightmare Batman's gun suggests a version of Injustice's inciting event: the Joker murdering Lois Lane.
Though it would be awesome to see all of these teases further expanded upon, it's worrisome from a narrative perspective. It's possible that Snyder will prioritize touching on as many story threads as he had planned for his future DCEU films in the series' 4-hour run time, but even with all that space to cram in details, there's a definite fear that the series will be overstuffed. The original film already featured a large cast. Snyder's cut will add new characters like Joker, Darkseid and DeSaad. Pa Kent and the Green Lantern Corps may also make appearances.
However, the appearance of so many DC characters in an uncompromising Snyder Justice League will be a feature, not a bug, for many fans. Even if Snyder bites off more than he can chew, being able to see his take on so many characters will be a dream realized.
Justice League stars Ben Affleck as Batman, Gal Gadot as Wonder Woman, Henry Cavill as Superman, Amy Adams as Lois Lane, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, Jeremy Irons as Alfred Pennyworth, Diane Lane as Martha Kent, Ciarán Hinds as Steppenwolf, Jesse Eisenberg as Lex Luthor and J.K. Simmons as Commissioner Gordon. Zack Snyder's Justice League will premiere exclusively on HBO Max in early to mid-2021.