Within the first hour of her film debut, 23-year-old Stacy Martin endures more brutality than most actors will face in an entire career. Her character in Lars von Trier’s Nymphomaniac, a meek schoolgirl named Joe, sets out on a mission to rack up sexual experiences in a cold, mechanical way — a process that includes letting Shia LaBeouf’s Jerôme take her vaginal and anal virginity in the same scene; participating in a competition with a friend to see who can sleep with the most men on a train; forcing a public blow job on a married older man; telling a host of guys in succession that they’re responsible for her first orgasm; and largely spending a whole lot of time nude and in strange, sometimes violent sexual contexts.

It’s not just uncomfortable in the way that near-pornographic sex scenes in films generally are — it also forces you to envision the dynamic between Martin, a fragile, underage-looking unknown, and von Trier, the oddball Danish filmmaker with a public reputation for pushing young actresses to their emotional limit.

So it’s a surprise to hear Martin explain she was often the one doing the consoling and the emotional housekeeping on the XXX-rated set. In fact, she found von Trier’s infamously bizarre sense of humor and his self-doubt to be a buffer against the discomfort of performing hours of stiff sexual acts on camera.

“He doesn’t take himself seriously. We would be doing scenes and he would come up and say, ‘I can’t believe I’m making you do this. I mean, you could be my daughter,’ kind of having this mini freakout,” Martin says, laughing a bit. “I was like, ‘I’m the one who’s supposed to be freaking out, not you. You’re supposed to be telling me what to do.’ But sometimes it turned out to be the opposite. There’s a fragility to Lars.

“People always say he’s a misogynist, and I’m like, you really don’t know him,” she adds. “You are a misogynist for thinking he’s a misogynist. Because he respects women.”

♦♦♦

You might say that reports of von Trier’s torturous work relationships with female actors on his films overshadow discussion of his actual work — if his films weren’t essentially reports of women’s torturous relationships with the world around them. No working director focuses so intently on women, or writes roles for women as consistently complex and tough as von Trier has in the last two decades. His female characters, Martin’s Joe included, are often young but world-weary, fragile martyrs but headstrong and capable of causing real destruction to themselves and others, playful in spite of their solemnity. It’s a tradition — think Hitchcock, or more recently Abdellatif Kechiche’s Blue Is the Warmest Color — with a predictably fraught outcome: heady male director writes ambitious female roles, pushes ingenues to their limits, elicits both brilliant performances and career-defining contention and backlash. You probably know the controversies well: Björk in Dancer in the Dark. Nicole Kidman in Dogville. The uneasy atmospheres von Trier cultivates onscreen begin to blur with stories of his real-life behavior.

Nymphomaniac — a two-volume epic that chronicles the life of a proud female sex addict (Joe) from childhood through age 50 — was a recipe for disaster of classic von Trier proportions. On paper it’s his most ambitious and provocative undertaking yet, a supremely graphic, jumpy, eight-chapter journey that spins in everyone from Uma Thurman to LaBeouf and a host of street-cast underage women. Only von Trier would have the gall to make a film like this, and only von Trier would submit himself to the challenges of creating it: casting women of all walks of life in a movie with a ludicrous title, filming them in violent sex scenes, and then presenting the finished product to a world that still associates him with the Cannes press conference where he made an off-color joke about sympathizing with Hitler. When the Nymphomaniac trailers surfaced, you could almost envision the gaffes and bizarre, misogyny-tinged stories that would emerge.

But for every woman who’s spoken about the difficulty of working with von Trier, there’s been another in recent years piping up with an almost familial air of protection to defend his vision and his modes of operation, even while confessing to his oddities. Kirsten Dunst, who played the depression-paralyzed Justine in 2011’s Melancholia, has explained that “His sense of humor takes a minute to get used to sometimes. … You could be offended by Lars … [But] he also made me feel very, very comfortable and safe too.” Kidman, who was run emotionally dry during the filming of Dogville, has said recently she’d like to work with von Trier in some capacity again. And it would not be surprising to learn that Charlotte Gainsbourg — who has starred in his last three films, including playing Joe as an adult in Nymphomaniac — had a von Trier shrine in her home. “I wish he couldn’t shoot with any other actress,” she said recently. “I’m very anxious, very unsure of myself … [but] I felt very, very normal facing him.” (“It’s as if he understood everything about me,” she’s also said.)

Whereas von Trier might have coaxed or forced challenging performances out of unknowing young actors in the past — Emily Watson, for example, had never even heard of the director before she auditioned for her Oscar-nominated debut in Breaking the Waves — Martin represents a new breed of von Trier collaborator, one who views his challenges with ambitious excitement. “There was no moment where I thought, Oh no, Lars is torturing me, or all those things people expected,” Martin says of Nymphomaniac. For her, the brutality of young Joe’s character marked an opportunity to make a take-me-seriously statement at the onset of her career. The days of the serendipitously brilliant von Trier performance may be gone, replaced by an era in which the director’s boot camp is legion, and a role in one of his films is a deliberate career springboard.

“What other people will see is that I’m not afraid of taking a part that is quite out-there and difficult,” Martin says. “It was either not doing that part, and missing out, and probably not doing anything, or doing the part and showing that I can do difficult parts. I’m up for a good challenge.” Martin isn’t another one of von Trier’s wide-eyed ingenues because she seems so self-assuredly steeled for his idiosyncrasies.

“Lars and Björk are two geniuses who have their own way,” Martin explains. “I just thought, my relationship with Lars will be different, because I’m not Björk.”

♦♦♦

Martin, who was born and raised in Paris and speaks with a confidently upper-class British accent, moved to the U.K. at 18 to study media and culture at the London College of Communication. Once she realized that she only enjoyed her drama classes and couldn’t envision herself pursuing an internship or a graduate program, she got down to business and began studying acting more seriously. She also modeled, she says, to subsidize the acting classes.

“Modeling was sort of a way to not work in a bar — it gave me time to really think about what I wanted to do, and things I liked and didn’t like.” One of the things she’s learned she doesn’t like is modeling itself — she recalls a grueling Purple magazine shoot in New York City with Terry Richardson that lasted for nearly 24 straight hours. (“He didn’t try to fuck me,” she assures me.) But just as she considered putting it aside altogether, her agent convinced her to go on a casting call that would unite her with the man who’d eventually introduce her to von Trier.

“He was this bonkers Scottish guy,” Martin says of the casting director on the modeling shoot. “He said, ‘Look, I’m auditioning for the next von Trier movie.’ I thought he was probably lying.” But she kept in contact with the casting director, auditioning for him twice before he sent her to Copenhagen to meet von Trier face-to-face. In traditionally unorthodox von Trier fashion, he’d initially planned to cast somebody who looked completely unlike Gainsbourg to play her younger self, but accidentally found that Martin — another French English beauty and a dead ringer for a young Jane Birkin, Gainsbourg’s mother — was simply the best candidate, emotionally and professionally, for the role.

“You’re looking for somebody who could not only play the part but also handle it,” says Des Hamilton, the “bonkers Scottish guy” and casting director responsible for bring Martin into the von Trier orbit. “Somebody who could enmesh themselves into that role and have the kind of stamina and mental capability to sustain the shoot.” Hamilton has been a key figure in helping von Trier cast his last three films so successfully; he suggested Gainsbourg for the boundary-pushing lead role in 2009’s Antichrist, setting off a director-muse relationship that’s taken on almost mythic proportions.

“I saw Charlotte in a café somewhere and I was mesmerized by her,” Hamilton says. “Antichrist needed a kind of otherworldly character, and I thought she was the kind of woman who could be that, just purely on that one experience.” Now, as von Trier has retreated from press interviews in the wake of the Cannes comments — he’s pictured in promotional photos for Nymphomaniac with a piece of tape across his mouth — Gainsbourg acts as a kind of mouthpiece for his validity and artistic vision. She’s made a point to explain that von Trier was very open with her about the difficulty of the sex scenes before they began shooting Antichrist, which infamously culminates with the actor performing a clitoridectomy on herself.

The hyper-confident Martin paints a similar picture of von Trier as an odd, insecure genius who primed her fully for what would be a daunting role. “There’s no way I would put myself in situations I wouldn’t want to be in, and I said that to him. This is my career, and it means a lot to me,” she recalls. “He sat me down and said, ‘If you’re uncomfortable or something’s bugging you, you tell me. I don’t care what it is — it can be because of the sex scenes, or it can be because of something else.’”

Von Trier, who has spoken about his longtime battle with depression and his experiences in therapy, relies heavily on improvisation and a democratic, communal atmosphere on his sets. The only component of the film Martin had complaints about was the awkwardness of the prosthetic penises in the blow job scenes: “It’s like, hard as this,” she says, knocking on the coffee table in front of her. “And they’re like, ‘What gloss do you want?’ It’s great,” she says sarcastically.

Martin has a kind of primness and severe beauty that belies her good nature — she had her hair pin-straight and pulled back, and wore a set of polite black ballet flats, dress pants, and a ruffled sheer black blouse when we met. There was something a bit startling about hearing such a composed person tell funny stories about prosthetic blowjobs, treating everything with openness and delight. She does not present herself as a wounded performer.

Nymphomaniac presented a special set of challenges for Hamilton, who was tasked with tracking down a group of young women, including children, to play the sex-addicted Joe at various ages. “I found a lot of difficulty in constructing an email trying to use the right words, and talking about what’s in the film,” he says. “But young actresses came forward. Those scenes [with the very young girls] are totally innocent.” He also explains that at this point in von Trier’s storied career, there are more name-brand actors clamoring for the chance to play a character like the young Joe than there are women deterred by the brutality or by von Trier’s reputation.

♦♦♦

Martin says she was deeply familiar with von Trier’s filmography before she got the role of Joe, and has long been enticed by the parts he creates for women. “It is very rare for a male director to write women so well. In most of his films, he sort of degrades the men, gives them this idiotic persona,” she says. “And then the women all come out really strong, even though they’re going through absolute hell.”

As much hell as Martin’s Nymphomaniac character incurs, it could have been much tougher. A few minutes into the second volume, the role of younger Joe abruptly shifts to Gainsbourg, who’s tasked with some of von Trier’s most shudder-inducing scenes to date. Joe visits a man known for his violence fetish, and she becomes sexually addicted to his lashings. Gainsbourg (and her body double) are pictured tied up and bent over, whipped until bruised, bloodied, and sexually satisfied. Meanwhile, her unsupervised infant son teeters toward the edge of the balcony of her apartment. The scenes make Martin’s role as young Joe look tame.

“I knew from the beginning I wasn’t doing those scenes,” Martin says when I ask if she would have been comfortable with them. “That’s the challenge as an actor. You put yourself in uncomfortable positions because that’s your job. Otherwise, just stay home and watch TV.”

It’s possible von Trier promised those scenes to the loyal Gainsbourg, who’s said she wished she could have played Joe throughout the entire film. Gainsbourg has also said she suspects von Trier might have exhausted his use for her altogether, and worries he won’t cast her in another one of his movies. Nymphomaniac might represent her reluctant passing of the torch to Martin. When I ask the 23-year-old if she plans to work with von Trier again, she nods excitedly.

“Definitely.”

♦♦♦

Carrie Battan is a writer in New York.