Emma Portner wishes I didn’t need to ask her about being hired to choreograph a West End musical aged 20, or going on tour with Justin Bieber, or being married to a film star. “I think I’m one of the only choreographers that has to deal with, in almost every review, going through that list of things first, and then it’ll talk about the work. It’s almost humiliating, and I wish that we could just look at the work sometimes.”

OK, so let’s talk about the work. The reason we’re chatting (over video call, she’s in Oslo) is because a duet Portner made called Islands is being performed in London for the first time, by the National Ballet of Canada. It was Portner’s first ballet. She was only 25 when it premiered in 2020 (danced by Norwegian National Ballet) but at that point already had a thriving career in commercial dance, music videos and film.

When the call originally came through to her agent, she turned it down. (She had pulled out of making a piece for New York City Ballet not long before.) But once persuaded, Portner brought her own singular sensibility to the piece, away from classical conventions, not least because it’s a duet for two women – something surprisingly rare in ballet. She didn’t set out to make a feminist work, she insists, and her interest in choreography isn’t political. “It’s much more about the actual inventiveness of the physical form itself.”

Portner’s Islands is not necessarily a romantic coupling, although it could be. “It’s an inherently queer duet because I’m queer and it’s two women,” says Portner, “But at the same time I liked the idea of leaving it open. You could find a mother-daughter relationship in it, or a sibling relationship in it, or is it the same person, dancing with the self?”

Disliking the distance that traditional tutus put between dancers, Portner went to the other extreme and starts out with both dancers sharing the same pair of trousers. “It sounds goofy when you say it,” she laughs. “Maybe it is goofy,” she muses. “I’d say it’s a pretty serious duet. Or is it so serious that it’s comical? I enjoy that tension.” From the snatch I’ve seen, it’s a very contemporary piece (no pointe shoes) that has some of the jagged attack of commercial dance and the yearning grace of ballet. The detailed tangling of bodies conjures illusions. “It looks like three heads at one point, or five legs,” says Portner.

Whatever it is, it worked, and after Islands, things snowballed. In four years Portner has made four more ballets. There was another in Norway, called Some Girls Don’t Turn; Bathtub Ballet for Royal Swedish Ballet, with 25 bathtubs on stage; Forever, Maybe for Sweden’s GöteborgsOperans Danskompani, and she recently made (and performed in) her fifth ballet, for Kammerballetten in Copenhagen. All before she turns 30 in November.

Portner grew up in Ottawa, a “quote-unquote boring” place, making her hockey-playing brothers perform dances she made up. A “horribly shy” kid, she struggled making friends at school, “but dance was a constant friend”. Portner insists she wasn’t very good at ballet (“awkward, lanky, inflexible”) but she was good enough to take part in the summer programme at the National Ballet of Canada – she tells a story about being so anxious there she threw up in her bunk bed – and to be offered a full-time place at the school, which her mum didn’t let her take up.

She went to a competition dance studio (think Maddie Ziegler and Dance Moms) but at 14 or 15 was given a key to the studio and would go in the evening to improvise, watching videos of contemporary greats such as Jiři Kylián and Crystal Pite (Pite is also on the bill at the London show and Portner is starstruck). At 17, she joined the prestigious Ailey School in New York, but left after seven months when she got a professional contract with choreographers Emily Shock and Matt Luck in LA. It was a video she made with Luck in 2012 that changed everything. A duet to a cover of Dancing in the Dark, the pair moving in a way that’s sharply staccato but somehow tender, too. “Matt and I made this film and we posted it on Facebook and basically overnight it changed my entire career trajectory, or gave me a career actually,” says Portner.

It’s still the reason people hire her, she says, finding the permanence of that three-and-a-half minute dance startling. “The whole reason I got into performing is because it is this fleeting thing that disappears. You get to experience this intense, intensely beautiful moment with people, in real life, and then it goes away.” She feels mortified at having her youthful creative efforts permanently online, “because I’m so rapidly changing”.

One of the unlikely things that came her way after Dancing in the Dark was the offer to choreograph the West End musical Bat Out of Hell. “It’s so random. Why me?” Portner says even now. She needed a job, she took it, and suddenly she was on the “god mic”, leading a whole cast. “It taught me so quickly just what it is to be a woman in the industry,” she says. “It was like a smack in the face of lesson after lesson of how hard it is.” But without that, she wouldn’t have had the courage to do a lot of the things she’s done since.

Ricocheting across the commercial dance world, Portner choreographed part of Justin Bieber’s tour in 2016, although she got more publicity for a strongly worded Instagram post she wrote about poor pay and working conditions, its final line: “The way you degrade women is an abomination.” It’s something she’s had time to consider since. “I feel so much remorse for calling him out publicly,” she says. “Because when I think back on it, he is from the same place that I’m from, the same age, and we were both just trying to survive some of the same industry forces that we had no control over.”

“I think at that time too, maybe I felt like I was on the brink of losing everything,” she adds. “My marriage [to Elliot Page], my identity as a dancer, and I was reckoning with things that happened in my childhood. So I wasn’t in a good place. I don’t have many regrets, but that’s one of them and I really do wish him well.”

The reckoning was with being abused by a teacher. “I used to not know how to talk about it, or if I even wanted to talk about it,” she says. “But I think it informs so much of the choices I made so young, and the sensitivity and fragility that I have as an artist as well, or just as a person moving through the world.”

Going back into ballet was a complex decision, for that reason. In fact, starting any new dance job “is like getting back in the bath of drama”. The experience of becoming tabloid fodder with Page has been bruising. And Portner suffers from a chronic illness, trigeminal neuralgia, affecting a nerve on one side of her face, which causes pain like “a combination of an electric shock and the feeling of knives stabbing”, which can be stress-related.

On the verge of 30, Portner is learning to take care of herself. She bought a cabin in the Canadian woods where she plans to spend half the year. She’ll read, meditate and “look at trees”. Now it’s time to breathe, and think about what she wants to do. “I think I have a few more ballets in me,” she says, but that might be all. There are other kinds of dance work, on stage and film, and she’s interested in design. She also has a band called Bunk Buddy and appeared in the films Ghostbusters: Afterlife and I Saw the TV Glow.

You can tell that Portner doesn’t believe she fully deserves the success she’s had (she talks about having a panic attack the first time she shared a bill with big-name choreographers). It’s not self-confidence driving her, but single-mindedness. “I’ve always had this extreme ambition and discipline,” she says. “But beyond that it’s also just dance itself. It’s something that I really have to do, daily.” What are the lessons she’s learned from this crazy decade? “It’s still just kindness at the end of the day,” she says. “You have to be kind to people. Your words really matter. The way that we speak about dance matters, and the way we make people feel matters.” She hopes the chaos of her 20s and its attendant gossip can be put to bed. “That’s my hope for the next 10 years, that we move on to the next area and I can just be who I am.”

• National Ballet of Canada is at Sadler’s Wells, London, 2-6 October