In a noisy brasserie in the 20th arrondissement of Paris, Héloïse Letissier leans in and wonders whether to ask for menus or await the server. “I have no charisma, so people never come over to me,” she says. As an experiment she recently walked home through the neighbourhood with her “chakras open”, attempting to engage strangers. “I thought I should try to be awake and make loads of eye contact,” she says, splaying her fingers either side of her eyes. “It worked!”

Maybe it was the chakras, but if your country’s biggest pop star was eyeballing you in the street, you’d probably smile back. Letissier, 28, is Christine and the Queens, the alter ego that transformed her from a depressed hermit into (whatever she says) a one-woman charisma machine. She broke through in France two years ago with debut album Chaleur Humaine (human warmth) – intimate, groove-heavy synth-pop that suggests Björk producing peak Michael Jackson. This March a semi-translated version scored stellar reviews in the UK. And since then, her live performances have won thousands of fans.

At Glastonbury in June, undeterred by a downpour and post-Brexit misery, Letissier flexed her muscles at the sky, and challenged the weather: “You want to fight, rain?” She won the battle, seamlessly intertwining excerpts from crowdpleasers Pump Up the Jam and Uptown Funk with her original material, while performing her own slippery choreography (a kind of avant-garde mash-up of pop, hip-hop and contemporary dance) with her four-strong troupe of male dancers. She accidentally dropped the mic after her last song but she could have done it on purpose – critics crowned her the act of the festival.

I'm so at ease on stage that the rest doesn't taste of anything. I'm always searching for intensity now

Towards the end of Letissier’s shows she extracts two stems from a bunch of flowers, introducing the first as Beyoncé, the second Rihanna. (“I wish I could eat Rihanna!” she told Glastonbury.) At Latitude the following month, overcome by a mid-set ovation, she got carried away and bit into the large orange lily doubling as RiRi. “I will actually speak to Rihanna later,” she announced after spitting it out. “This was a terrible idea to eat a flower onstage.”) She then extracts a broken twig, representing herself. “But you know what’s good, guys? I get to be in the same bouquet! There’s no way to be perfect with me – just be yourself, come as you are.”

This could all be a bit faux-modest, but Letissier pulls it off because she’s such a brilliant performer, and so different to pop’s reigning warlords. She adopted the Christine persona after a lifesaving encounter with some drag queens, and her bilingual lyrics confront the shame she’s felt as a young queer woman. In an age of gender-fluidity and social-media-induced anxiety, she feels like the pop star we’ve been waiting for: Tilted, a song about embracing awkwardness, stealthily ascended to Radio 1’s A list, and the album spent weeks in the top five.

Back from requesting the menu, Letissier explains how being Christine onstage has overhauled her existence. She has noticed herself walking differently, though says she anguishes over social interactions – not that you’d notice. In a loose shirt and big round glasses, she’s funny and focused, all clownish gestures and quick intelligence. There’s just one problem. “It made my life a bit more difficult because I’m so at ease on stage that the rest doesn’t taste of anything. I’m always searching for intensity now because it was like that on tour.” To fill the gap, she’s “trying to fall in love! Not succeeding! And then writing great songs”.

Tilted video

The day after we meet, she is due to leave for another intensity hit in Oslo, before wrapping two-years of Chaleur Humaine gigs in the UK in November. Her tour should have ended ages ago, and Letissier recently turned down dates in Japan to stop her schedule from snowballing out of control. “The clock is ticking inside,” she says, grabbing her chest. “It feels cheesy to say, it makes me feel like a diva – I need to make it really genuine and honest, and somehow I feel like I would stop being like that on stage.”

Music seized Letissier early. At four, she pounded on the dinner table and demanded piano and ballet lessons. “I think it says something about discipline, and I always liked discipline.” She raises her fork and pulls an impish face. “I love saying that, it’s so creepy. I love trying to match a really hard expectation.”

Her parents weren’t stagey, and educated themselves out of working-class families – her father is an English professor, and her mother teaches French and Latin. She recently bought a place nearby, and invited them up from Nantes, her hometown. “They were shrinking,” she says, hugging herself, “looking around like, ‘You can’t afford that’, and I was like, ‘Yes, I can!’” Literature was the only thing they pushed on her. Jane Eyre ruined high school. “I was basically searching for Rochester. Writing letters, wanting connections through the mind. The dudes were searching for boobs, nice girls.” She wails. “I was like, no! Let’s be connected to death!”

The worst thing that could happen to me – if I don't write I am going to choke, like a fish

Her father introduced her at 13 to the author Sarah Waters – she thinks for the strong female characters, although it proved handy when her first girlfriend arrived three years later. “My introduction to gay sex was with Sarah Waters. I knew what was done thanks to her. Like, ‘Oh! The whole fist?’”

Letissier’s sexuality was never an issue for her parents, although she says she battled some internalised shame. She can trace her queerness back to the age of four while watching Michael Jackson’s Captain EO at EuroDisney. “I remember being excited for the first time, sexually excited. At some point he’s dancing, and he’s opening his jacket, and there is a rainbow shining out of his chest, and I was like, oh!” She laughs. “I know, it’s so queer! My whole life is queer.”

In her teens, convinced she needed plastic surgery, she obsessed over a video of his face morphing. She lacquered on makeup to look like Marie Antoinette, so her father gave her Judith Butler’s book Gender Trouble, which describes gender as a performance. She listened to her parents’ Klaus Nomi records and wrote gory novels. Her classmates weren’t always kind.

Rather than go to a traditional state university as most French kids do, she enrolled in an intensive two-year course that prepares students to attend an elite École normale supérieure, and in 2008 started theatre studies in Lyon, hoping to be a director. Freaked out by the lack of structure, she defected to a nearby university, which proved worse – incredibly, only boys were allowed to direct. “When I asked for explanations, they were like, ‘Because it’s like that,’” she recalls tartly. Letissier rebelled, and staged a play without permission. In February 2010, the faculty heard she was planning a repeat, and expelled her.

On stage in Boston in May, with her four-man dance troupe. Photograph: Burak Cingi/Redferns

It was her first encounter with misogyny. She barricaded herself in her flat, stopped eating, and wrote plays about her anger, personified as a furious spectre named Christine who let her period blood run freely. Meanwhile, her latest girlfriend started transitioning, and dumped her. “It was not a good relationship, quite a destructive one,” Letissier says tentatively. “She – he – was not really loving me. Because we broke up then, it was like I was a reminder of something he used to be and he didn’t want to be any more? You get to feel like you’re – not a waste, but you’re someone in the past.”

Rejection left her “blank”, unable to read or write. “The worst thing that could happen to me. I think I can miss a leg but if I don’t write, I am going to choke, like a fish.” She watched Tarzan on repeat in the dark. “At some point I thought: I have to get out, otherwise I’m going to lie down here … Then London came quite naturally.”

Letissier’s next chapter is already entering pop mythology. In 2010 she took herself to London. In Soho, she stumbled into gay club Madame Jojo’s (since shut down) and watched a shambolic drag act. The three queens adopted this agonised waif, teaching her that theatre could be anything at all; to bend rules, rather then fulfil them. They encouraged her to adopt a persona and write songs, and dismissed her self-pity. “It killed the drama, actually. They’re like, ‘So, you got dumped … and?’ I was escaping the Jane Eyre: ‘There is no Rochester!’”

Christine was properly born, named in tribute to her drag mentors. Letissier once said she might not be alive without Christine. She grits her teeth. “I don’t like to talk about it because it becomes immediately what I don’t like being – drama-queeny – but suicide for me is a real question all the time. I’m interested in this concept of choosing at some point to end things. I was really considering suicide for real. I’m way too much of a coward to do it, even if I wanted to. But it was purely unbearable, and I had nothing to sustain me, so Christine was me having a new writing technique, and so then a new way to be.”

A French journalist painted her as a hysteric after she mentioned suicide. “This is why I was like, let’s not think about me as a female singer. Let’s think about me as a voice, because I was trying to escape rules.”

Letissier moved to Paris and got two tattoos: “One of us” on her left wrist, “We accept you” on the right, from Tod Browning’s 1932 film Freaks, about deformed carnival performers. She started writing on GarageBand and posting Cocteau-ish videos to YouTube, wearing suits and antlers. Her first three songs were iT, Be Freaky and Kiss My Crass, the latter a celebration of smelliness as defiance. Her flatmates convinced her to enter culture magazine Les Inrockuptibles’ talent contest. Two months later she made the final. “She was so far ahead of everybody that we thought it would be silly to give her the prize because she obviously didn’t need it,” says founding editor JD Beauvallet.

Christine and the Queens performing on the Other stage at Glastonbury. Photograph: Richard Isaac/Rex

French/Finnish duo the Dø saw Letissier at the finalists’ gig, and offered her an opening slot. When her computer kept crashing, she talked freely to the audience. Hecklers yelled “get naked!”, and Letissier shouted that she was naked already. “For the first time in my life, I didn’t try to make people want me,” she says. She brought scissors onstage, “in case I wanted to emasculate anyone!” she trills. “So I was playing with them, looking at dudes, and you can tell the dudes are fearing for the penis. It was not punk, because I am not punk, but I think French people were, like, chanson française – ready for a Lolita singing songs, and there I was with my scissors.”

Her reputation spread, until every French label wanted to sign her – and turn her into a French Lady Gaga. She crosses her eyes. “These other dudes were like, ‘We see this Lana Del Rey potential’.” She gesticulates at her boyish body. “I was like, ‘Where do you see that?!’” Eventually, in 2012, she signed with Because (Metronomy, Charlotte Gainsbourg), who didn’t want to change anything. Letissier sidelined the antlers, recognising mainstream pop’s potential as a Trojan horse for weirdness. There was the odd misfire: Tilted was originally called Cripple, the chorus, “I actually enjoy being a cripple.” She didn’t realise the implications until she played Brighton in May 2013, “and there was a huge embarrassed silence. I thought it was really ambiguous! But it’s not.”

In February 2014 she was nominated as breakthrough live act at Les Victoires de la Musique (France’s Grammys), and invited to perform. Under a spotlight, she danced like a minimalist Michael Jackson and threw glitter from her gold suit pocket. In rehearsals, the 70-year-old producer had yelled in her face, “Do you think people are going to be interested in that?” But it made her an instant sensation. “I’m kind of resistant to being told no, not being wanted,” she says, grinning. “It fills me with energy. When I’m headlining, sometimes I feel less comfortable than when I’m not expected, because people love me already, and what am I going to do with that – disappoint them?”

Chaleur Humaine was released in France that June. On playful opener iT, she declares, “I’m a man now.” Half-Ladies was dedicated to women who don’t fit feminine ideals, and Safe and Holy celebrates dance as “a way to shut down intrusive gazes, a way to reclaim my body as my own”. Letissier accepts that most people listen to the tunes rather than her progressive lyrics about queerness – she identifies as pansexual, falling in love with personalities rather than genders. She finds the general attention “flattering, in a way. But it’s interesting, I don’t know if I did that unconsciously to be sure that I could be introduced, because I’m always thinking in terms of a whole career: if people get to know me first, then let’s dig the dirt for the second record.”

Surprised by how melancholic Chaleur Humaine turned out, Letissier wants to bring her live energy into a sweaty, carnal second album. “I feel like I’m more a grownup now, with a horny perspective on life that’s shaped my songs differently,” she says, raising her eyebrows. “A huge taboo now is still a woman’s desire. We are forgotten – it’s like we are supposed to sustain other people’s desire because we are desirable objects. What if we desire ourselves? So I feel like what could be shocking is not even me being naked, but me wanting to fuck someone and talking about it really simply – ‘I just want to fuck your bones.’”

Héloïse Letissier. Photograph: Karen Robinson/The Observer

She thinks the simplicity will also help her lack of a “coherent” self. “I’m kind of trapped in my contradictions with my sexual desires. Because I’m experimenting so much with gender-bending and listening to everything that happens to me in terms of genderless energies, I have a hard time finding partners that can match me. They still want me in the end to be a girl or a queer woman, and I don’t want that. I want to shatter everything and experiment because I want gaps, uncertainty – I’m really attracted to that.”

Christine’s suits were originally conceived to deflect the male gaze. Now Letissier is comfortable to be seen as a sexual object. Her attitude is: “If I’m going to be commented upon for my physique, let’s show them something new to comment upon.” She points out her gym across the road, where she’s working towards resembling 90s Madonna, her body ideal. “I’m fully becoming what I want to become, thanks to Christine, so I’m going to head towards the macho and the tougher side. When I’m doing photoshoots, I still have this stupid idea that I want to be pretty, and I don’t want to think about it any more.”

Letissier criticised French Elle after they photoshopped her February 2015 cover beyond recognition, yet she still wants to feature in women’s magazines. “I should not desert those spaces because I hate them – I should try to bend them because I can.”

It could be her mission statement: one of her dancers previously quit a major pop tour after being asked to wear heels “because he was not a ‘faggot’”, she quotes. His homophobia attracted her, “to see, naively, if the lines could move a bit. And I think they can.”

She’s doing the same for France’s image of pop stardom. After November’s terrorist attacks on the Bataclan in Paris, she ran a pop-up radio station, interviewing diverse artists to widen the definition of French identity as opportunist politicians promoted exclusion. She’s been retweeting France’s nascent Black Lives Matter movement following 24-year-old Adama Traore’s death in police custody in July. In the UK, we crave smart, political musicians, but in France, Letissier says, “it’s not really well seen when an artist takes a position, because we are supposed to be like clueless singing puppets”.

This sounds strange, given that France makes intellectuals into celebrities. “But France is really different now, I think. Because of the terrorist attacks, we are not in reflection, we are in reaction, and I think maybe it’s the same for [post-Brexit Britain]. It’s all short-term thought about being elected, and it’s terrible because politics is not a place where you can think about what togetherness means any more. And I have a responsibility like any citizen – more so, because I have more reach.”

Letissier worries that questioning her identity promotes this individualism. But her lyrics are the antithesis of narcissistic pop, and she wants to be contagious, not admired. She concedes a little. “Lyrics of really huge pop bangers right now make me think about advertising – sentences that could thrill you but are empty in the end. And for that, I don’t really feel like I do belong in the pop realm.” Kendrick Lamar is more her bag. “I didn’t grow up in Compton, I don’t know what he’s really talking about, but because it’s personal – money and love – it strikes universal terms. This is being inclusive. If an old lady can sing my song that comes from a queer young girl’s perspective, this is, for me, pop music at its best. You get to have many realities going on at the same time.”

The brasserie has emptied, and Letissier is late for a blood test – she confesses she’s a hypochondriac. Caffeine is her only vice, and she bailed on a recent date to smoke her first joint “because I’m an introvert,” she shrugs. “I want to try to write under a substance to see if, like people say, it’s better or not. I don’t really believe it’s better because I think for me, writing is so much being in that state already.”

It transpires there is a limit to how far she’s willing to push boundaries. “But then again, losing control – I’m not a fan of that.”

Chaleur Humaine is out now (Because Music). Christine and the Queens plays Brixton Academy, London; Manchester Apollo and Glasgow’s O2 Academy in November