Recently, it was reported that Joaquin Phoenix slapped Vanessa Kirby behind the scenes while filming Napoleon. Both are no strangers to extreme method acting.

It would certainly be an interesting dynamic to see in the Apple+ movie that was described as a "spectacle-filled action epic that details the checkered rise and fall of the iconic French Emperor Napoleon Bonaparte" in the official synopsis.

It also says: "Against a stunning backdrop of large-scale filmmaking orchestrated by legendary director Ridley Scott, the film captures Bonaparte's relentless journey to power through the prism of his addictive, volatile relationship with his one true love, Josephine, showcasing his visionary military and political tactics against some of the most dynamic practical battle sequences ever filmed."

Here's a closer look at the Joker actor and The Crown alum's slap "agreement" that just made fans a lot more thrilled to see the film.

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Inside Joaquin Phoenix's Method Acting

Joaquin Phoenix in a still from Joker
Joker star Joaquin Phoenix
via: The New York Times

Phoenix has done a lot of crazy things to prepare for a role. "You really start to go mad," he said of losing more than 50 pounds for Joker after deciding with director Todd Phillips that the character had to "look hungry and unhealthy."

"As it turns out, that impacts your psychology," he said of his "doctor regimented" restrictive diet, "and you really start to go mad when you lose that much weight in that amount of time." Speaking of mental health, he once pretended to have a meltdown on The Late Show With David Letterman for Casey Affleck's mockumentary drama, I'm Still Here.

Of course, that's nothing compared to having his jaw wired shut for The Master. "I actually went to my dentist and I had them fasten these metal brackets to my teeth on the top and the bottom, and then I wrapped rubber bands around it to force my jaw shut on one side," he told National Public Radio back then.

On the set of the same movie, Phoenix studied wild animals trying to escape cages, which led him to smash a toilet. "You can see that their brains don't seem to be functioning anymore," he said of his research to The New York Times.

He continued: "It's [a] pure reaction, and you see the muscles going. I knew that's what I wanted to capture – they're hurting themselves, and they don't even know [it], but something inside is saying get out, get out."

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Vanessa Kirby Enjoys Exploring Dark Places In ActingVanessa Kirby could get intense with method acting

Kirby once said that "empathy is the job for an actor." Speaking to The Talks about her career-defining performance in Pieces of a Woman, the English actress said that working with Shia LaBeouf, "We realized that we have to go to some really dark places and that we have to court each other through that with a lot of respect and trust and delicacy."

But unlike Phoenix, Kirby seems more comfortable with the psychological toll of method acting. "When you are all dark, you need to throw light, too. There is not one without the other," she continued.

"For me, going deep into dark nights of the soul is kind of the joy of being a human. Feeling a wide range of things as possible. If you feel intense pain, on the flip side there is a lot of exhilaration. It's a gift going to dark places. I never feel scared."

She even credits her process to improving her real-life connections. "And I think that fragility and vulnerability has helped me so much in the job because I understand the sensitivity," she explained to the magazine. "It helped me empathize with people that are going through a difficult time. And empathy is the job for an actor."

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Why Joaquin Phoenix Slapped Vanessa Kirby While Filming Napoleon

Joaquin Phoenix at the Joker Premiere During the 57th New York Film Festival Instar

Phoenix recently revealed that he slapped Kirby on the set of Napoleon because they agreed to "shock each other." She apparently gave him permission to do "whatever" he felt like doing for their scenes.

"She said, 'Look, whatever you feel, you can do,'" the actor said in an exclusive interview with Empire alongside his leading lady. "I said, 'Same thing with you.'"

"She said, 'You can slap me, you can grab me, you can pull me, you can kiss me, whatever it is,'" he continued. Their characters notably had a turbulent romantic relationship, hence Kirby's request for that intense passion.

"We had this agreement that we were going to surprise each other and try and create moments that weren't there, because both of us wanted to avoid the cliché of the period drama," Phoenix recalled, noting that "by that I mean moments that are well-orchestrated and designed."

Kirby added: "It's the greatest thing when you have a creative partner and you say, 'Right, everything's safe. I'm with you. And we're gonna go to the dark places together.'"

Napoleon will first premiere in cinemas in the US and the UK on November 22, 2023. It will be available on Apple TV+ at a later date.