‘Joker’ star Joaquin Phoenix on how he started to “go mad” during transformation for role

The DC film premiered over the weekend

Joker star Joaquin Phoenix has discussed the transformation he underwent to take on the iconic role, revealing that he began to “go mad” ahead of filming.

Making its debut at the Venice Film Festival this weekend, the new DC movie tells the origin story of Batman’s infamous arch-villain. Phoenix appears as Arthur Fleck, a mentally troubled man who later transforms into the comic book charlatan.

In a new interview, the lead actor spoke of shedding a significant amount of weight preparation for his performance, and how becoming the Joker affected his state of mind.

“You start to go mad when you lose that amount of weight in that amount of time,” Phoenix told Daily Beast. “There’s a book that I read about political assassins and would-be assassins that I thought was really interesting, and kind of breaks down the different types of personalities that do those sorts of things.”

He went on to discuss how reading Fleck’s journal and book of jokes helped him form his incarnation of the Joker.

“Very early on in the rehearsal, I was given the journal that he had—his journal and joke diary. And that was really helpful, because I had been there for a couple of weeks and wasn’t sure how I was going to start, and Todd [Phillips, director] sent this [empty] journal,” he explained.

“I didn’t know what to write, so I asked [Todd] for some suggestions, and after a few days, I ignored his suggestions and suddenly it was coming out. It became a really important part of the discovery of the character at that time.”

With many viewing his character as “tragic”, Phoenix said that he was “interested in the light of Arthur”. “It wasn’t just the torment; it was his struggle to find happiness, to feel connected, to find the warmth and love—that’s the part of the character I was interested in and worth exploring,” said the actor.

At its premiere on Saturday (August 31), Joker received an eight-minute standing ovation from the audience. Elsewhere, director Todd Phillips has teased a potential sequel to the movie.