Joaquin Phoenix is well-known for the intensity he brings to the role he plays, and his time on the set of Joker was no different.

Speaking to the The New York Times, director Todd Phillips revealed that Phoenix walked off the set multiple times, sometimes in the middle of filming a scene.

"In the middle of the scene, he'll just walk away and walk out," Phillips said. "And the poor other actor thinks it's them and it was never them -- it was always him, and he just wasn't feeling it.” After taking a breathe, he would say, “we’ll take a walk and we’ll come back and we’ll do it.”

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Not everyone, however, experienced this side of Phoenix. Co-star Robert De Niro said that Phoenix was professional the entire time and praised the actor's acting style.

"Joaquin was very intense in what he was doing, as it should be, as he should be," De Niro said. "There's nothing to talk about, personally, on the side, 'Let's have coffee.' Let's just do the stuff."

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Directed by Todd Phillips, Joker stars Joaquin Phoenix, Robert De Niro, Zazie Beetz, Bill Camp, Frances Conroy, Brett Cullen, Glenn Fleshler, Douglas Hodge, Marc Maron, Josh Pais and Shea Whigham. The film arrives in theaters Oct. 4.