Kristen Stewart’s new film casts her as personal shopper and spiritual seeker; caught between cities, trying on different outfits for size. She is exhausted and driven, haunted by the past and unsure of the future. The script calls her Maureen but maybe that’s just a fig-leaf. Stewart insists that, whatever role she takes on, she is basically playing herself.

Or perhaps it’s the fate of every teen star to grow up on camera and make their missteps in public, to the point where it becomes hard to tell where the person ends and the performer begins. Stewart, after all, was still at high school when the Twilight franchise opened her up to the world. Stable door, horse bolted, and so what choice does she have? She says: “I used to be fearful. I used to feel violated. But that was a defence mechanism; I think I’ve grown out of it now.” She talks like an old-timer, although she’s not yet 27.

We meet in a beachfront bar at the Cannes film festival, with the crowds massed behind cordons on the street outside. The actor crash-lands on the couch like some 1920s flapper, complete with peroxide hair and a sheer silver dress. She explains that as soon as the interview is over, the finery goes back in its box. She’s exhausted, she’s done. She’s taking six months off.

Personal Shopper is her second collaboration with French film-maker Olivier Assayas, hard on the heels of her César award-winning turn in Clouds of Sils Maria. It’s a marvellous, mercurial ghost story, haunted by anonymous text messages as Maureen juggles her shopping duties with attempts to make contact with her dead twin brother. Stewart says that the shoot was an ordeal – 16-hour days, six days a week – which probably accounts for Maureen’s hollow-eyed appearance. “By the end, I look ghoulish and I think that I earned it,” she says.

Actually, she gives a terrific performance – in that she’s awkward and raw; a splatter painting made flesh; a woman turned inside out. Stewart’s lines have a curious habit of trailing off at the end. Her gaze skips to the side, as though searching for an escape. Her detractors can (and have) identified this quality as evidence of poor acting technique, which is rather missing the point. You might as well accuse Holden Caulfield of being an unreliable narrator, or complain that Marlon Brando totally goes to pieces in On the Waterfront. Stewart’s very gaucheness is gorgeous. Paradoxically, I think it might be the making of her.

In Personal Shopper, Stewart plays Maureen, who juggles her shopping duties with attempts to make contact with her dead twin brother.

“I can be nothing other than myself,” she says. “I know actors who say: ‘Oh, this role had nothing to do with me, it’s just the character’. And I think: ‘Yeah, but it is your interpretation of the character.’ Because you can never get away from being you. That’s always going to be there. That’s the persistency of life. An interaction with a good director might bring you closer to aspects of yourself that might have been less apparent before. But it’s still about self. It’s still all about me.”

Apropos of nothing, she tells me how she first started performing: singing in a school production when she was nine. “And I was so self-conscious, so not a natural performer, just some shaky little weirdo. But there was a scout in the audience, someone who sends out 100 headshots of kids to the studio. And I somehow caught wind of this and thought: ‘I want that, I want to act.’”

It helped that her parents were in the business. Her dad was a set designer; her mum a script supervisor. “So I grew up on set and it always felt like summer camp. Because when a crew comes together, it’s like your own band of pirates, protecting your treasure. It takes over your life. My mum and dad would come home so late. I’d get up at one in the morning and run out and they’d have craft service in their bag and all these crazy stories about their day and they’d even smell different.” She wrinkles her nose, as if sniffing the air. “They’d smell like the world. Like they’d been out in the world.”

By her mid-teens, she had already amassed a decent showreel. She co-starred as Jodie Foster’s diabetic daughter in David Fincher’s Panic Room, played the tragic victim in Speak and provided the soulful side-note to Sean Penn’s Into the Wild. But it was her role as Twilight’s mopey, lovelorn Bella Swan that sent her career stratospheric. The franchise grossed a reported $3.3bn (£2.7bn). Forbes magazine estimated her 2012 earnings at $34m. Once Twilight broke big, there was no looking back.



“I feel curious about who I would be if I had gone to university,” she says. “Because I worked pretty fucking hard in high school. And sometimes I feel pissed off at my own inferiority. Because there’s stuff I don’t know. But then there’s always stuff you don’t know.” She pulls a face; shrugs her shoulders. “And I still read a lot. My favourite author is John Steinbeck. East of Eden is my bible. I love Kerouac. Bukowski. In high school, I loved The Outsider.” She racks her brains for further names.

I ask if she misses being anonymous and she admits that she does; so much it’s not funny. “Because I’m such a people person. I’m so interested in them that it’s really annoying they’re so interested in me. Because I can’t look at anyone without them noticing me. I want to be able to sit in a room and people-watch. And that’s difficult for me. It’s a unique perspective, for sure.”

New York is not so bad; she can sometimes pass unnoticed. Cannes is the worst, she says; Cannes is insane. She gestures towards the street, where the festival cars can barely move for tourists and photographers. “I mean, if we walked outside right now, I’d be in physical danger.”

I suggest that we test it. How about we go for a stroll? Stewart gawps as though I have taken leave of my senses. “No way, man,” she says flatly. “There’s no way in hell.”

The problem, I suggest, is that we feel we know her already; that we have some spurious claim on her innermost secrets. Try as she might to keep her private life private, the details spill out. She has to wade into the fray to regain control of the drama. When her romance with Twilight co-star Robert Pattinson broke down, for instance, Stewart responded by issuing a public apology. More recently, her relationships with the French singer Soko and effects specialist Alicia Cargile have presented a fresh quandary. Out of the blue, her sexuality was reframed as a political statement. She found herself embraced as Hollywood’s most high-profile gay actor, a de-facto poster-girl for the LGBT community.

“Well, yeah,” she says. “And that’s been nothing but positive. I mean, it’s hard to talk about. I don’t want to seem presumptuous, because everyone has their own experience. The whole issue of sexuality is so grey. I’m just trying to acknowledge that fluidity, that greyness, which has always existed. But maybe only now are we allowed to start talking about it.”

Does that make her a pioneer – a rare Hollywood A-lister sticking her head above the parapet – or has the whole culture changed? “Oh, I think things are changing. I mean, I don’t think I would have approached my life differently if that hadn’t been the case. But who knows? Individually we are all part of that change and so I can take some credit for it, I guess – there’s no reason why I should shy away from that. But all the prejudice; it’s going for sure.” She reconsiders. “I mean, yeah, it’s definitely still there. People still have some horrendous fucking experiences. But it’s cool that you don’t have to nail everything down any more. That whole certainty about whether you’re straight or gay or whatever.” She flashes a quick smile and reaches for her water. “You’re not confused if you’re bisexual. It’s not confusing at all. For me, it’s quite the opposite.”

With Juliette Binoche in Clouds of Sils Maria. Photograph: Allstar/CG Cinema

Her press duties are complete; the Cannes film festival closes. Stewart spills back into the world; a lovely, awkward work in progress. She shoots a short film, Come Swim, that premieres at Sundance. She crops up in a supporting role in Ang Lee’s Billy Lynn’s Long Halftime Walk; co-stars as a lawyer in Kelly Reichardt’s Certain Women. The press are reporting that she has a new girlfriend, model Stella Maxwell. Photographers snap them on a New York shopping spree.

The world, for its part, keeps spinning too. Donald Trump is elected president; the swing states turn from blue to red. Stewart, installed as the host of Saturday Night Live, jokingly recalls the tweets Trump sent back in 2012, urging Robert Pattinson to dump her. She says if Trump didn’t like her then, he probably won’t now. “Because I’m, like, so gay, dude.”

One night in late February, I talk to her again, on the phone. There is so much to catch up on, I don’t know where to begin. She says that Sundance was great and that the SNL gig was a blast. She didn’t know what to say, but then remembered Trump’s tweets. They were weird at the time; today they’re surreal. “So it’s probably the most fascinating, bizarre thing to have ever happened to me,” she says. “To be personally called out by the future president. It’s like I’ve become a piece of history.”

With Robert Pattinson in The Twilight Saga: New Moon.

The world felt brighter, more fluid when we spoke down in Cannes. Since then, the stakes have got higher. The liberal agenda risks being rolled back. Stewart reckons that, if anything, the election was a wake-up call. It has forced her to choose her projects more carefully, to weigh up their social value. She mentions that she recently pitched in on a benefit album for Planned Parenthood. “And obviously that’s all because of the person who I’m not even going to name. Because the truth is, he’s terrifying. He’s not funny at all.”

The phone line crackles; our time’s almost up. She says: “If there is one silver lining in all of this, it’s that I know that art, music and film is going to experience a boom, directly as a reaction to what’s happened in this country. Maybe we’re seeing that already; we probably are.” Stewart barks a short laugh. “Listen to me,” she says. “Always looking for the silver lining.”

• Personal Shopper is out on 17 March. A Guardian Members preview screening of Personal Shopper, followed by a Q&A with director Olivier Assayas, takes place on 15 March at Picturehouse Central, London.