January 8 2011: The visionary film director tells how he got the performance of a lifetime from Natalie Portman in his Oscar-tipped thriller, Black Swan

Darren Aronofsky is sliding down the sofa, looking positively sleepy, when I tell him what I really think of Black Swan, his supernatural horror film set in the world of ballet. It is, I venture, completely ridiculous, outrageously camp, over the top, glossy and gritty, scary as hell. “Yeah! Awesome. Cool.” He sits up straight, his jet lag vanishes and he grins. “It’s all about walking the line of ridiculous and sane. I grew up in Brooklyn and the Cyclone rollercoaster in nearby Coney Island was just the best entertainment; I like films to be a rollercoaster ride in which the audience has to hold on. I like to keep people interested and excited.”

Black Swan is not only interesting and exciting, it is also dark, sexy, stylish, stylised and utterly seductive. It’s already an arthouse sensation in America and is being put up for awards on an almost daily basis, notably for a handful of Golden Globes and a record-setting 12 nominations for the Critics’ Choice Movie Awards. At its heart is Natalie Portman, who gives the performance of a lifetime as a ballet dancer whose grip on reality appears to be flimsy.

Aronofsky, whose parents were both schoolteachers, clearly likes clever women. Portman studied psychology at Harvard University and Rachel Weisz, with whom he has a young son, read English at the University of Cambridge. When we meet, Aronofsky talks about watching Japanese anime films with his son, Harry. “He was into My Neighbour Totoro for a long time and, about a year ago, I showed him Spirited Away. He was scared when the girl’s parents turn into pigs; he still talks about it. So now he watches very, very gentle stuff. I think Snoopy is sometimes a little intense for him. But I know he’s going to be watching plenty of terrible, nasty things later on . . .”

I ask Aronofsky if he is ever recognised in Manhattan, where he lives, and he says: “Not really. Maybe if I’m walking around with Rachel. But we’re very under the radar.” Low key? “Very low key.” He says that he’s good at having downtime with his family between projects. “I shut off pretty well. There is some stress that carries over, but after a day or two it kind of fades. We try not to talk about work too much; our four-year-old is not interested in it, so we mostly talk about Lego.”

It’s odd, then, when I read a few weeks later that Aronofsky and Weisz, Hollywood’s No 1 Jewish intellectual couple, have split up after nearly a decade together. TMZ, the celebrity news website, reports that the couple, who were not married, had been separated for some months. “They remain close friends and are committed to raising their son together in NYC,” the story continues. “Sources tell us the couple will seek joint custody of their four-year-old son, Henry Chance.” Just for good measure, TMZ adds that Weisz has been linked with Daniel Craig since the two actors worked together last year.

During our interview Aronofsky didn’t exactly volunteer information about his life with Weisz, but then neither was he in the least bit defensive, distracted or jumpy. After learning about the separation I think back to the interview and the only curious thing he had said was about spending time alone. It’s obvious when you watch an Aronofsky film — whether it be the hugely ambitious and not entirely successful The Fountain or the quiet desperation of The Wrestler — that he gives everything.

He must, I suggest, need time to decompress between films. “That’s very true. Every time I finish a project I try to backpack, to disappear off the planet.” On his own? “Yeah . . .” So he’s good at being on his own? “Yeah. I actually need it because when you’re a director and you have 400 people working around you, it f***s with you. So it’s nice to be completely independent and not have to be what other people are projecting on to you. To just be a traveller. It’s great. I like to really disappear.”

Whatever the true story behind the couple’s separation, there is no question that the timing is unfortunate because everyone’s attention should really be on the brilliant Black Swan. It’s a simple enough story of ambition, but Aronofsky’s audacious direction has not only pushed Portman to the limits of her acting abilities — it has also prompted furious debate.

It has been compared, inevitably, to Powell and Pressburger’s ballet masterpiece, The Red Shoes, and to the work of the Italian king of horror, Dario Argento. The American press has alternately embraced Black Swan as “an exciting fairy tale for grown-ups” or rejected it as simply not working. It’s the kind of divisive film that simply cannot be ignored.

Black Swan tells the story of a ballerina called Nina, played by Portman, desperate to take the lead in a new production of Swan Lake. Vincent Cassel, as the controlling, sadistic artistic director, gives her a chance to play the dual role of the white swan queen and her evil black twin. In her desperation to please, Portman descends into a world of hopeless paranoia and selfloathing. She breaks the bones in her toes, makes herself sick to stay skinny, scratches her shoulders furiously as black feathers push through and even nonchalantly peels strips of skin from her fingers.

The fear that she will never be good enough is complicated by the omniscient Mila Kunis, who as Lily is everything Portman is not: effortlessly sexy, playful, free. Portman even tortures herself about usurping the previous prima ballerina (Winona Ryder) and there’s a super-creepy scene in which the former visits the latter in hospital (“a meta-casting stunt!” laughs Aronofsky, referring to Ryder once looking very much like Portman). The dancing is great to watch, but it doesn’t matter if it’s not your thing; Black Swan simply happens to be set in the nothing-is-quite-what-it-seems world of ballet.

You could say that it’s about self-sacrifice and the lengths some women go to in order to achieve their notion of perfection, but that makes it sound terribly dull. Instead, the relentless blurring of reality and fantasy, Barbara Hershey’s crazed mother living vicariously through her daughter and a Portman-Kunis sex scene all make for a pretty full-on rollercoaster ride.

In fact Aronofsky says that he’s surprised by the adjective that people keep coming up with to describe his film. “Black Swan might be dark compared to what else is out there in the marketplace; it’s certainly sexy and scary. But there’s plenty of humour in it and what’s been most exciting for me is how many people are saying the film is fun. I’ve never had that before. My first film, Pi, was challenging; Requiem for a Dream was harrowing; The Fountain was interesting and The Wrestler was sad. “ ‘Fun’ is a good word. I like it.”

Given the intense melancholy of his previous films — how could anyone forget the relentlessly grim but viscerally brilliant Requiem — I expected Aronofsky to be a brooding presence. Yet, flopping on the sofa in a Central London hotel room, he is urbane and relatively expansive. Sporting a skinny moustache, black glasses, a Pennsylvania Ballet baseball cap (“they really helped us out; I rarely wear anything else just now”), a brown wool hooded jumper, beaten-up jeans and white New Balance trainers, he looks younger than 41. Like the women he likes to work with, he is clearly super bright — he studied anthropology at Harvard — but is self-deprecating, too.

I ask about something I read in which he apparently described himself as “an existential humanist”. He shoots me a puzzled look, then laughs. “Where did I say that? I don’t even know what it means! Actually, I think I might know where it came from. I had a girlfriend in college who looked at my short film and said, ‘Yeah, it’s existential humanism’. It stuck in my head because it sounded kinda cool, but I’ve still no idea what it means.”

Perhaps it’s easier to think of his films not in some pseudo-intellectual way but in terms of the great performances that he draws from his cast — it is almost certain that Portman will be Oscar nominated for her portrayal of the fragile, vulnerable and naive Nina. And it’s hard not to applaud her performance simply because of the selfsacrifice involved. In what is fast becoming a cinematic trend — James Franco was endlessly pinned by a boulder to a canyon wall while filming 127 Hours and Mark Wahlberg built a boxing ring in his house in preparation for The Fighter — Portman spent the best part of a year having ballet lessons. As a result, as much as 90 per cent of what you see on the screen is Portman dancing.

You can almost feel her pain when the bones in her toes snap, when her protruding chest bones seem ready to cut through the skin, when she tries to be as sexually charged as Kunis. Given that Mickey Rourke had to put on about 50lb and throw himself around the ring in The Wrestler, would it be fair to call Aronofsky a slightly sadistic director? He laughs. “Mickey I had to work because he’s a lazybones. Lifting his pinkie is painful for the guy. Talent comes so naturally to him that he usually doesn’t have to work that hard. So I had to get the whips out, to pull and push at the same time. He knew I was medicine; the acting was going to taste foul, but it would make him better. In his heart he knew I was really making the film for him.”

Portman could not, it turns out, have been more different. “She is a perfectionist in her own way. She’s a very responsible, grounded, smart woman. I was never concerned she’d take it over the edge. When she got a little too skinny I got a little nervous because we were working really hard — the days were a work-out, both physically and mentally. At a certain point” — he emits a small laugh — “I really wanted her to start eating more. It was hard to do because we just didn’t have time. But I was never properly concerned about her.”

Did he have to pull her back, stop her from taking the role too seriously? “No. It was a matter of opening the door and inviting her in. Showing her the project, the character. She was so excited about taking on a role like that. It’s what it’s all about for most real actors. It’s all about the hero’s journey: Ulysses, Moses and Noah and all the great stories that are practically part of our DNA are about characters overcoming great challenges.”

Although Portman is dating the ballet dancer and choreographer Benjamin Millipied — whom she met on the set of Black Swan; he plays the Prince and was a crucial adviser on the closed-door world of ballet — it’s not exactly unheard of for directors to fall in love with their actors. I put this to Aronofsky and he laughs. “Actually it’s the opposite for me. You have to be really, really connected but not emotionally. You need to be objective, especially when you’re going to extreme places. You can’t afford to feel bad for the actor. You have to keep reminding yourself that the actors are enjoying it, because it’s their job! It’s what they’ve been waiting their whole life to do — to cry and scream on film. The reason young actors get into acting is to go off the wall.”

And what of the scenes in which Portman masturbates in the bath or has frantic sex with Kunis? Did anyone feel compromised on set? “Everyone was nervous and uncomfortable. Natalie and Mila are very good friends so it was extremely awkward. You’re kissing a friend and having oral sex with her. I had two days put aside for that scene, but I can feel the discomfort in my actors pretty well. In the end I just wanted to bang it out, so we shot in half a day. But Natalie was very easy with her sexuality; she was pretty game. She’s 29 but is always cast young, so I wanted to be the first to push her into womanhood.”

There is time for one more quick question. Best, perhaps, not to get into existential humour again, so I ask how long Aronofsky has had that moustache. “I’ve had it since The Wrestler. I lost it for a few weeks but then I was like, I like it. I don’t know why I have it . . .” It looks quite good, I say. He laughs, sounding oddly relieved. “Thank you! I definitely get a mix of responses. Kind of like my films. But the important thing is that I had my moustache before Brad Pitt had his, so I think I’m ahead of the curve.”

Black Swan is out on January 21