Ben Affleck is set to suit up (at least) one more time as Batman in The Flash. The first solo movie for the DC Extended Universe's resident speedster has been in development for years, but has recently started making forward progress again. Andrés Muschietti (It and It Chapter Two) will direct, with Ezra Miller reprising his role as Barry Allen from previous DCEU movies Suicide Squad and Justice League.

Michael Keaton, who played Bruce Wayne in Tim Burton's Batman and Batman Returns, will also be returning to the role for The Flash, which will introduce the concept of the multiverse into DCEU canon. Other versions of Batman are also expected to appear, and according to Muschietti The Flash's plot will imply "a unified universe where all the cinematic iterations that we’ve seen before are valid." (Including LEGO Batman? Sure, why not.)

Related: Why Marvel & DCEU Are Both Creating Multiverses In 2022

The Flash will be loosely based on the popular DC Comics story Flashpoint, in which Barry Allen goes back in time to save his mother's life and accidentally sets off a chain of events that radically changes the universe. He wakes up in a world where Bruce Wayne died as a child, Thomas Wayne is Batman, and the Amazons are at war with the Atlanteans. While The Flash isn't an exact adaptation of Flashpoint, it will still keep the most important elements from the DC Comics story. Here's why Ben Affleck is returning as Batman for The Flash - and why the movie needs him.

Ben Affleck's Batman & Ezra Miller's Flash Are Already Connected

Bruce Wayne talking to Barry Allen

Though 2017's Justice League - a Frankenstein movie comprised of fragments of Zack Snyder's original vision and substantial rewrites and reshoots by Joss Whedon - left many DC fans disappointed, it did establish a bond between Affleck's Bruce Wayne and Miller's Barry Allen. We may get to see more of this bond in the upcoming release of the Justice League Snyder Cut. Though Barry was already operating as a superhero independently, it's Bruce who convinced him to join the Justice League and take on the extraterrestrial threat of Steppenwolf. When Flash is overwhelmed by his first taste of battle, it's Affleck's older, wiser Batman who counsels him to just focus on saving one person. Their bond will be important when it comes to The Flash's story, as Muschietti explained to Vanity Fair:

"[Affleck's Batman is] a very substantial part of the emotional impact of the movie. The interaction and relationship between Barry and Affleck’s Wayne will bring an emotional level that we haven’t seen before. It’s Barry’s movie, it’s Barry’s story, but their characters are more related than we think. They both lost their mothers to murder, and that’s one of the emotional vessels of the movie. That’s where the Affleck Batman kicks in."

The Waynes were famously killed in a shooting outside a theater, as has been depicted many, many times in movies before. Barry's mother, Nora Allen, was killed by the supervillain speedster Reverse-Flash, who hated the Flash so much that he travelled back in time in order to hurt him in the worst way possible. Since this will be the first ever live-action solo movie about the Flash, it will introduce audiences who aren't familiar with the comics to Barry's own tragic origin story. It makes sense to link that story to the death of Bruce Wayne's parents, given the connection that the two characters already have in the DCEU.

Related: What Michael Keaton's Batman Return Means For The DCEU

Ben Affleck's Batman Is The DCEU's Original Bruce Wayne

Zack Snyder and Ben Affleck on the set of Batman V Superman Dawn of Justice

Because The Flash is a movie about a whole multiverse with different versions of Batman, it would actually be more conspicuous if Affleck's Batman wasn't in it. Though many actors have played Batman before him, "Batfleck" is the original Batman as far as the DCEU's Barry Allen is concerned. "He’s the baseline. He’s part of that unaltered state before we jump into Barry’s adventure," Muschietti said. "There's a familiarity there." With the live-action DC movies now splintering off into soft reboots like Suicide Squad and independent stories like Joker, The Flash needs to have a grounding element to anchor it firmly in the same world as Batman V Superman: Dawn of Justice, Man of Steel and Justice League. It wouldn't feel as meaningful for Barry to go wandering off into other worlds if his starting point wasn't a place that audiences are already familiar with.

Ben Affleck Wanted To Play Batman Again

DCEU Batman Ben Affleck

Affleck was originally set to write, direct, produce and star in The Batman, but directing duties were later handed over to Matt Reeves (Dawn of the Planet of the Apes) and the movie shifted to focus on a younger iteration of Batman played by Robert Pattinson. Affleck separated from his wife, Jennifer Garner, in 2015 and the divorce was finalized in 2018. He also struggled with depression and alcohol addiction, entering rehab programs in 2017 and again in 2018. While Affleck was passionate about the role of Batman and particularly committed to Snyder's interpretation of the character, he wasn't in a place where he was ready to shoulder the burden of directing and starring in a blockbuster superhero movie. Speaking to the New York Times, Affleck recalled:

"I showed somebody ‘The Batman’ script. They said, ‘I think the script is good. I also think you’ll drink yourself to death if you go through what you just went through again.'"

Not only does Affleck appear to be in a more stable place now, a supporting role in The Flash allows him to return to the role of Bruce Wayne without the same pressures that he faced in leading the cast of Batman V Superman and Justice League. As The Flash producer Barbara Muschietti put it, "Right now he’s in a place where he can actually enjoy being Batman." While there has naturally been speculation about Affleck having a possible cameo in The Batman, The Flash is a better fit for his version of the character. This way he can continue to be a part of the universe conceived by Snyder, while Pattinson can build a Batman of his own without being overshadowed by his predecessor.

More: What Ben Affleck’s Batman Return Means For Robert Pattinson’s Movie