He added, "The interaction and relationship between Barry (Ezra Miller) 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."
According to the report, Affleck got the script last week and agreed to join the project this week.
The announcement comes just one day after Ben was spotted out in Los Angeles wearing a t-shirt sporting the Flash's lightning bolt symbol. Maybe he was trying to tell us something?
Ben isn't the only former Batman who will be back for the film. As the movie is an adaptation of the popular Flashpoint comic arc, it will explore the DC multiverse -- and have Michael Keaton reprise his role from Tim Burton's films.
According to Muschietti, Keaton will have a "substantial" role in the film as well, while Affleck will be in the movie to show Barry's "baseline ... that unaltered state before we jump into Barry's adventure."