Describing Halsey’s second record as a concept album would be to understate its preposterousness. Its title, Hopeless Fountain Kingdom, is her own concept of a purgatory-like realm whose back story is so deeply finessed that it includes individually named carp. There’s some Greek mythology thrown in along the way, too. But the imagery around the album’s release, and its spoken-word interludes, also pay homage to Baz Luhrmann’s Romeo + Juliet.

“I went balls-to-the-wall with this one,” is Halsey’s own way of recognising what is also a rather good pop record.“When people ask me about it I say: ‘Yeah, I went through this really terrible breakup and I naturally did what any normal 22-year-old girl would do – I called Baz Luhrmann.” Luhrmann loved the project so much that he got involved with the album’s promotion and expressed a desire to work with Halsey in the future. It has also been wholly embraced by the New Jersey-born singer’s fans, whose symbiotic relationship with the singer makes the hysteria surrounding peak-era Gaga seem nonchalant in comparison. Those fans have clearly responded well to the frankness with which Halsey talks about her sexuality, being bipolar and the product of an interracial marriage, and the struggles she faced as a teen. But they seem most seduced by the escapist worlds in which she situates her music. As she talks about her passion for video gaming, the Easter eggs and intricate backstories woven through her songs begin to make more sense, although none of this high-concept japery will come as any surprise to those who have been following her expeditious rise to the fringes of pop’s A-list. In 2014, her debut EP Room 93 centred on the broad theme of being stuck in a hotel room. The following year her album Badlands, including breakthrough hit New Americana, dwelled on mental isolation in a city based loosely on Las Vegas.

It’s Vegas where we find ourselves today. Tomorrow, Halsey will perform her current single Now Or Never at the 2017 Billboard Music Awards under a huge sign that reads HOPELESS – a bold image to throw out into 2017’s meme-obsessed pop sphere. “Of course it is,” she accepts. “But I can control that. I’m the one putting it out there.”

It’s no surprise that Halsey thinks one step ahead of potential detractors; like all the best pop stars, this former Tumblr teen has experienced fandom from both sides, having found early attention under her real name, Ashley Frangipane, while knocking out covers and parodies on social media. One successful video, The Haylor Song, pastiched Taylor Swift’s Trouble and centred on One Direction fans’ concerns about Harry Styles’ then-girlfriend.

We’ve met for lunch at a Japanese restaurant situated, like so many restaurants on the main strip, within an underground casino. Rather spectacularly, on sitting down she’s ordered herself a mid-afternoon pint of Stella, which simply underscores the feeling that Halsey’s quite unlike most of her peers, and all the better for it. Her new album looks set to top the platinum-selling success of its predecessor and she recently spent three months at No 1 in the US with her Chainsmokers collaboration Closer. Meanwhile, above ground the streets are lined with billboards for shows by artists who have experienced, shall we say, something of a plateau in terms of appeal. With that in mind, it seems hard to avoid the message of one particular new Halsey song, Angel On Fire, that seems to be about a faded icon. The song is a bit about that, she agrees, but the real story is far more bleak. “It’s about me having a party at my house that I’m not attending,” Halsey says. “I locked myself in my bedroom, went to sleep and let everyone party until 6am. Then I did it again. And again, and again …” Over the course of several months last year, she’d invite people to parties at her LA home, then hide. When asked why, she begins reasonably (“I like entertaining people, I just don’t like having to do it myself”), then sounds like a sociopath (“It’s awesome because the next week people come up to you and say: ‘Your party was sick!’”). And then, when we discuss one specific line in Angel On Fire – “nobody seems to ask about me any more” – it all comes out.

Halsey at an ACLU benefit concert in LA, April 2017.

Photograph: Broadimage/REX/Shutterstock

“Everyone thinks they know what’s going on in my life, because they read it on the internet,” she says. “I’ll buy a table at a restaurant, I’ll buy bottles, I’ll pay for everyone, then we’ll go to the movies. People I barely know. I’m trying to make friends, I’m trying to get to know people. Nobody says thank you because they’re like: ‘Ashley has money.’”

This extends, she says, to her family; they don’t call to see how she is, which clearly troubles her, but not as much as the fact that she doesn’t want them to call, because if they did she’d only tell them how tired and busy she is. Fame and success are often dangerous not because of what they do to you, but because of what they do to the people around you. Right now, Halsey seems to feel pressure from both sides. “I used to be this social queen,” she sighs. “I could go anywhere, make anyone like me, go to any party, talk to anybody. I used to have no shame in walking up to someone on a plane or train and sitting down and chatting to them. I used to just talk. I used to be obsessed with people; now, I’m terrified of them.”

News of Halsey’s woes will likely prompt a spontaneous social media conga line from the surprising number of people who have taken a dislike to her. Some are unconvinced by aspects of her back story, including the claim that she was homelesswhen videos posted online at the time tend to depict the same bedroom, peppered among Instagram posts of shopping hauls. Today Halsey clarifies that period as being “in between living situations”. “I get it all the time,” she adds. “People say: ‘How could you be homeless, you were a One Direction fan?!’ It’s like, can’t you be both? Everyone wants to pick on me all the time. What do I have to do, an Excel page with a fucking timeline of my life, just so you guys will give me some credibility?”

One thing I was smart about was knowing that if I wanted to be a musician, I needed to keep up my appearance.

At this, she indeed offers up a timeline of her life, or at least the recent part. Halsey graduated from high school at 17 and moved in with an abusive boyfriend; she knew she had to get out of that situation, but because she hadn’t gone to college her parents had disowned her and wouldn’t offer financial support. She moved to the city and spent time living with a guy that she had started dating, who was a drug addict. “The dark part of it was when I was living with a heroin addict and not speaking to my family,” she adds. “People might say it doesn’t ‘count’, but it counted to me. Thinking all my friends were going to die and being by myself and being terrified. It was easily the darkest time of my life. The one thing I was doing was maintain my persona online. I never let anyone know I didn’t have a home. If there’s one thing I was smart about at the time, it was knowing that if I wanted to be a musician, I needed to keep up my appearance.”

On that point Halsey adds that the infamous bedroom belonged to her friend Tori, but in light of her previous stance on Taylor Swift (water under the bridge now, she insists), she finds it hard to demonise many of those who react strongly to her. Looking back on The Haylor Song, she says: “I understand it was pack mentality, and knowing that in stirring up that discourse we would all be on the same side about it, which is exactly what people do to me now. When you hate someone’s girlfriend or brother, or hate another band, that’s a gang mentality. People would rather talk together about something they hate than something they all love. And that’s so blatantly clear in our nation at the moment. People in political parties are stans: they sit online, they wait to see anyone who’s going to say something bad about their favourite, and they fucking trash them. They direct hate at any opposer. The political parties have literally turned into fandoms.”

The spirit of pop enthusiasm is strong in Halsey. While picking at dim sum, she talks passionately about Swift, Kendrick Lamar and Ryan Adams, and you get the feeling that if Halsey wasn’t a pop star having Gifs made about herself, she would be making them about other artists. But her forensic knowledge of pop, combined with her much-trumpeted social conscience, makes it all the more surprising that her new album includes a guest turn from Migos rapper Quavo, whose comments on homosexuality and subsequent apology both raised eyebrows. Presumably Halsey, whose album also includes a groundbreaking bisexual love song with Fifth Harmony’s Lauren Jauregui, did due diligence?

“I think he’s misunderstood,” she says. “Just because I choose to be a socially conscious artist, and I’m pretty good at it, that doesn’t mean every artist is going to be equipped to be politically correct. I don’t think he’s inherently homophobic, I think he’s in a tough place of trying to explain what he means. I agree his apology was bullshit but I can’t police everybody.” When I suggest that one place she surely can police everybody is within the walls of her own album, she pauses. “Yes, I can,” she adds, “and there’s a lot of people I wouldn’t put on my record. Iggy Azalea: absolutely not. She had a complete disregard for black culture. Fucking moron. I watched her career dissolve and it fascinated me.”

By this point Halsey needs a cigarette, and we say goodbye. Her own career seems to be in no danger of dissolving, but something she says suggests that she may one day change its direction for the sake of self-preservation: “Ultimately, I’m going to end up a songwriter. I don’t think I’m going to be an artist for ever. People who do it have a sick masochism.”

Halsey plays the Other Stage at Glastonbury Festival, Friday, 5.40pm. Hopeless Fountain Kingdom is out now