Director Andy Muschietti has revealed the tragic reason behind Michael Keaton’s Batman walking away from the cape and cowl in The Flash. And it’s pretty dark. Discussing the DC outing in a new behind-the-scenes featurette released courtesy of Warner Bros. Entertainment, Muschietti explains that Keaton’s Dark Knight decided to retire from being a superhero after killing a criminal in front of their child and thus going against his code and mirroring the event that led him to become Batman in the first place.

“I always said something should happen to Bruce Wayne to want to stop being Batman, and my idea was, he did something that goes against his code and killed a criminal in front of [the criminal’s] child—not knowingly, but he still did it.”

Muschietti continues, revealing that the reason for Batman’s retirement needed to be heavy enough to make someone as obsessed as Bruce Wayne walk away from the fight. Surely we can all agree, reflecting his own childhood trauma would do just that.

“Which is an exact mirroring situation of what happened to him when his parents were killed in front of him [next to] Monarch Theaters, and that created the monster that Batman is.”

For whatever reason, this is never mentioned in the movie itself, with Keaton instead simply saying that Gotham no longer needed Batman. So, we can add this to the ever-growing list of crucial story information that comes after the fact. An unfortunate trend of some modern blockbusters.

“He just couldn’t cope with it and that’s why he decided to shut off his other side – The Batman. He hasn’t been able to forgive himself and now the way we find him [in The Flash] is an evolution of that.”

RELATED: 5 Reasons Why Micheal Keaton is Still the Best Batman

The Flash Deleted Scene Explores the Reason for Batman’s Retirement
Warner Bros. Pictures

As well as these details from Muschietti, a deleted scene from The Flash has also now been released (via The Flash Film News) and finds the two versions of Barry Allen discussing Batman’s retirement and the painful situation that caused it.

Worlds collide in The Flash when the superhero uses his superpowers to travel back in time to change the events of the past. However, when his attempt to save his family inadvertently alters the future, he becomes trapped in a reality in which General Zod has returned, threatening annihilation. With no other superheroes to turn to, the Flash looks to coax a very different Batman out of retirement and rescue an imprisoned Kryptonian — albeit not the one he’s looking for.

Directed by Andy Muschietti from a screenplay by Christina Hodson and starring Ezra Miller as Barry Allen aka The Flash alongside Sasha Calle, Michael Shannon, Ron Livingston, Maribel Verdú, Kiersey Clemons, Antje Traue, Ben Affleck, and Michael Keaton, The Flash finally landed in theaters last month after years of setbacks. Met with mixed reviews, The Flash has struggled at the box office, grossing $268 million worldwide against a budget of $200–220 million. However, this does not include marketing costs, meaning that The Flash is now considered one of the biggest box-office bombs of all time.