Director Andy Muschietti talks about having Affleck as Batman. Says that Michael Keaton's role is substantial.
https://www.vanityfair.com/hollywood/2020/08/ben-affleck-returns-batman-the-flash-multiverse-keaton"His Batman has a dichotomy that is very strong, which is his masculinity—because of the way he looks, and the imposing figure that he has, and his jawline —but he's also very vulnerable," Muschietti said in an interview. "He knows how to deliver from the inside out, that vulnerability. He just needs a story that allows him to bring that contrast, that balance." Affleck got the script at the end of last week and agreed this week to join the project. "He's 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," the director added. "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." "I'm glad to be collaborating with someone who has been on both sides of the camera, too," Muschietti said. "He understands."