After he landed the role of Arthur Fleck, the deeply troubled and delusional sidewalk entertainer and would-be stand-up comic who eventually becomes a murderous psychopath in Joker, there was one place that Joaquin Phoenix did not visit as he prepped for the part: comic book shops.

No perusing the week’s new reads or classic trade paperbacks at his local comics emporium for the intense 44-year-old actor, and no calls to DC Entertainment HQ to request that a stack of Joker stories be messengered to his house. “That’s true,” says Phoenix as we sit down at the press junket for Joker to discuss the film and his portrayal. “I wanted it to be unique and I wanted it to be based on kind of my interpretation and Todd (Phillips director/co-writer) and Scott (Silver, co-writer)’s interpretation.”

What all three had in mind and has been brought to life in the film is indeed a fairly radical reinterpretation of the most infamous villain in Batman’s storied rogues gallery. For one thing, the Joker has never had a definitive origin story before in nearly 80 years of existence, and his long career of crime and chaos has always been steeped in his ongoing conflict with the Caped Crusader.

read more: Joker Review

Joker not only gives the character a back story but largely downplays the comic book aspects of the Batman mythos in favor of a darker, more grounded aesthetic. “I think that Todd and Scott had written this great script that both felt very real and now,” says Phoenix. “But also I think had elements of the comic and the world of Gotham and Joker that I thought was important. And it seemed to kind of weave both those things together effortlessly. But yeah, I don’t know why, I just felt like I need to kind of approach this without any expectation or baggage and just try to create something that feels fresh.”

Phoenix also acknowledges that pursuing the character on his own terms — he has shied away from the comic book/superhero genre until now, most notably turning down an offer from Marvel to play Doctor Strange — gave him a better appreciation for how malleable some of these creations can be.

“I think particularly Joker, there seems to be like an infinite number of ways to interpret this character,” says the actor. “Which is I think what’s so appealing about him and appealing for different actors. It was a character that was constantly surprising, and only seemed to function when we weren’t clear about what his motivations were — which is the antithesis of what it normally is when you make a movie.”

Phoenix continues, “I mean, typically you want to be very clear about who the character is and what defines them and what motivates them. But it seemed like anytime Todd and I would kind of come to some understanding of why he was behaving the way that he was in a particular scene, it kind of would lose this energy, it would lose its fire. And it suddenly, it just would become bland and we’d be disinterested. The more that it kept us guessing, the more that it revealed to us.”

As an example, when asked whether he had a grasp on the Arthur side of the character or the Joker persona first, Phoenix says that working on one completely changed his perspective on the other. “We shot for several weeks as Arthur and I had this kind of idea of who Arthur was and what I wanted to do with the character that Todd and I had kind of talked about,” he explains. “And after a few weeks we shot Joker for the first time, for five days, and I really had no idea what I was going to do with Joker.

read more: The Actors Who Have Played the Joker

“And as we started filming, these different unexpected colors started emerging, things that I didn’t anticipate,” Phoenix says. “After that I went back to Arthur and I had no interest in him at all. But more than that, I realized that everything that I had done with him prior was wrong. And it made me have this kind of radical shift in the way that I approached Arthur.”

Although Phoenix initially wanted to shoot the film in sequence, so that he could evolve his performance organically toward Joker, the standard method of shooting out of order ultimately helped him redefine Arthur Fleck’s journey into darkness.

“It was really interesting because when we were prepping for the movie, I said, ‘We’re going to shoot in order, right? Because I can’t play Joker until the end.’ And Todd said, ‘It’s absolutely impossible with our schedule,’” he recalls. “I was really troubled by that. Now in hindsight, I’m so grateful that happened because I think playing Joker revealed to me something about Arthur that, you know, I didn’t see and I didn’t know. And it allowed us to kind of go back and change the Arthur character.”

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Phoenix’s Joker is an intrepretation of the character different from both the outlandish Jack Nicholson take in 1989’s Batman and Heath Ledger’s Oscar-winning agent of chaos in 2008’s The Dark Knight. It may be the most psychologically complex version of the Clown Prince of Crime to date, and it’s one that is already spurring debate and controversy. One thing’s for sure: it’s no joking matter.

Joker is out in theaters next Friday (October 4).

Don Kaye is a Los Angeles-based entertainment journalist and associate editor of Den of Geek. Other current and past outlets include Syfy, United Stations Radio Networks, Fandango, MSN, RollingStone.com and many more. Read more of his work here. Follow him on Twitter @donkaye