In an interview with Collider, Brendan Gleeson casually remained silent about the mysterious plot elements of Joker: Folie à Deux. When asked what made him want to be in the film, he said, “It wasn’t the material, which is a great way to keep me from answering criteria questions. It was the performance of the first film.”
He states that he knew Joaquin Phoenix from working with him on The Village and that was reason enough to work on the sequel. He continued: “And that performance, I’m still impressed by that. That performance as Joker in that first film. It was one of the most extraordinary performances I’ve ever had. And for Todd [Phillips] … having reworked the film to make this possible, I didn’t have to ask twice. I really don’t.”
Gleeson told the Irish Times that he’s taking the time to “smell the coffee” and being more selective about the roles he takes on. He said what he’s looking for: “The excitement you get when you get something through the door that absolutely sings. And that you have to get up on it instead of trying to pull it up by your boots. When I smell it, when it jumps through the window, it just won’t go away.”
He said after landing the role of Mad-Eye Moody in the Harry Potter films, he knew he would lose his anonymity. “It’s difficult to browse a store. It’s a high price and I don’t like it.” However, working with Phoenix and Phillips was enough to get him signed on to another major franchise.