The trials of St Antony

How to describe Antony Hegarty's voice? Since the release of his band Antony and the Johnsons' 2005 album I Am A Bird Now (which chronicled his experiences as a transgender person and was the surprise winner of the Mercury prize, selling upwards of 500,000 copies), there have been many attempts to categorise his sound, ranging from "chamber pop" to "ethereal torch singing". One of his early mentors, Lou Reed (hardly the gushing type) said: "When I heard Antony, I knew that I was in the presence of an angel."

As a fan, and I'm a huge fan of Hegarty's, it's hard not to descend into hyperbole when it comes to his most beautiful songs: "Hope There's Someone" from I Am A Bird; "One Dove" from 2009's The Crying Light; the exquisite "My Lord, My Love" from the deluxe edition of the latest album, Swanlights. At its best, his voice whispers to the listener about mortality and eternity.

Indeed, only Hegarty seems prepared to be matter of fact about his voice. "It honestly wasn't that special when I started – no one thought I had a nice voice as a kid," he says bluntly when we sit down to talk, at a table full of lit candles, in the dressing room for the Manchester International Festival (MIF).

Hegarty says that, far from being some "gift from God", his voice was all about persistence and application. "I really think anyone can sing. It's a matter of rain or shine, not giving up, applying yourself. That's what I did: I copied my favourite singers and learned – singing for hours and hours, years and years. Eventually," says Hegarty, "I got my voice."

Ironically, Hegarty and I get off to a shaky start, owing to my turning up to interview him with my own croaking voice, a remnant from a virus. Hearing it he looks aghast, and angles himself away from me. It's understandable – he's in Manchester for the final stages of rehearsal for The Life and Death of Marina Abramovic, a staged biography of Serbian-born "godmother of performance art" Abramovic's life, to be performed at the MIF, directed by Robert Wilson, featuring music by Hegarty and avant-garde "soundscape artist" William Basinski.

I spend the first few minutes of the interview trying to convince Hegarty that I'm not infectious, and even (rather desperately) try to bond with him about the fact he once lost his voice mysteriously for a year and had to be treated with steroids. Hegarty listens to these croaking, rasping excuses with blank-faced politeness, before saying firmly at the end: "No, yours definitely sounds like an infection," adding more kindly, with a tap to his throat: "Perhaps a bit of asthma in there?"

It's a "closed" rehearsal for The Life and Death of Marina Abramovic, but I'm briefly allowed to watch Antony and the cast. I won't pretend that I have the foggiest what's going on, but it all looks very interesting, even without the full set and props. People walk around in "Marina" masks, while Wilson's team directs via microphones. Actor Willem Dafoe (narrating and performing) dons first an army uniform and then a bathrobe. At one point Abramovic perches on a makeshift bed, with coffins lined up at the side, while Hegarty sings with his back to the audience. A close friend of Hegarty's, Abramovic tells me that he was her only choice for the symphony. "My life has been about so much pain, and Antony wrote the songs for this piece like he was making a costume, sewing directly on to my skin."

Back in the dressing room Hegarty tells me that it's a far cry from his youth in Manhattan in the 1990s, studying experimental theatre at NYU and staging underground cabaret nights with his troupe Blacklips (their act variously involved throwing offal, and flailing around in piles of "Aids corpses").

"That was much more anarchic," he says. "Bob has such a particular structured aesthetic; it's all about exactitude. Everything has to be perfect to have the quality he's looking for, down to every hand movement being choreographed. I love it. It's an exciting and interesting way to work."

Hegarty sips his drink on his side of the candles. He's sometimes described as if he's freakishly large, a Hagrid-style man-mountain, which he isn't – he's just solidly built and tall (6ft 4in). There's a delicacy, indeed femininity, about the way his dark hair hangs around his pale, intense face; in repose there are times when he resembles Leonardo Da Vinci's "Mona Lisa".

Conversationally, when he warms up, Hegarty can be spiky and engaging on the subjects he's interested in, which is quite a list: gender, capitalism, the environmental concerns that infused his last two albums – he's disappointed that President Obama hasn't taken a stronger stand. It's probably to be expected that, as a transgender man, he muses a lot about "the subjugation of the feminine aspect by the male". "It's something we haven't tried as people yet – radically empowering our feminine aspect." When I ask if he has feminist sympathies, he looks surprised: "Not just sympathies – I identify very strongly with feminists."

He seems to makes no bones about being on the precious side of arty, though he can be disarming, saying of the 138-page book of his art that comes with the deluxe edition of Swanlights: "Was I that good at art when I was younger? No, and I'm still not now." However, while Hegarty can talk up a storm about theories and ideas, what he calls "being an artist, participating", he's somewhat unforthcoming about his personal life or, as he puts it: "the domestic details". However much I hint, there's no getting out of him whether he has a boyfriend. He's also tetchy to the point of rudeness about going over his back story. "Do you really want to rehash it again?"

Well, yes. As a fan, I love the tales of the young Antony romping about the Lower East Side dressed in a woman's slip, shaven-headed, with "Fuck Off" written on his forehead. Surely, Antony, such a lengthy, unorthodox apprenticeship should be celebrated? Hegarty smiles: "I suppose it did take a long time to get where I was going. I'm not sure I'm even there yet. I'm amazed it keeps rolling forward, really."

Born in Sussex in 1971 to an Anglo-Irish family, Hegarty moved with them to Amsterdam, then California, when he was 10. Already sensing his "transgender difference" but not knowing how to make sense of it, Hegarty was drawn to British acts such as Kate Bush, Marc Almond, the Cocteau Twins, Yazoo and Culture Club, as well as practising singing to Nina Simone. He felt especially drawn to photographs of Boy George – "pure femininity radiating from his face" – and, later, the performance artist Leigh Bowery.

Hegarty says that he was "sociable and creative" growing up, a habit he hasn't lost. He's a seasoned collaborator, working with, among others, Reed, Björk, Yoko Ono, Boy George and Rufus Wainwright, a multitude of fringe artists (some of whom featured when he took over the Guardian's music site last year) and various orchestras around the world, including the London Symphony Orchestra. "I'm always drawn to collaboration, working in community," says Hegarty. "To me that's three-quarters of the joy – to be in dialogue with someone else. I think oftentimes as a kid I moved towards creative work as a means of breaking my own isolation."

By 12 he was writing songs, progressing to whole musicals (based on the oeuvre of John Waters). He was rejected by the Royal College of Art but NYU accepted him, and he wasn't nervous about moving to New York. "I was hardboiled, renegade, ready to move to the big city. I wanted to be in the centre of the storm."

It was probably the best place for a transgender boy to be. Hegarty has sung and spoken about being transgender many times, most notably in "For Today I Am A Boy", with its opening lyric: "One day I'll grow up/I'll be a beautiful woman". One wonders whether some people are still confusing transgender with gay or transsexual. "The emergence of a transgender aspect is very different to the emergence of sexual orientation, though there are intersecting circles," explains Hegarty.

He believes it's primarily a "family issue", not, as he's colourfully put it in past interviews, "all about his meat and potatoes". Does this kind of prurient interest irritate him? No, says Hegarty. "People don't have as much experience thinking about it as I do. It's not as if they talk about it in school: 'OK, children, there's Jack, there's Jill, and there's Zane' or whoever. We're raised to believe that there are only two ways of raising children: a pink and a blue model. God forbid you transgress those boundaries."

As one of the few prominent transgender people, does he feels it's his duty to speak out? "I don't see it as a duty," says Hegarty, "I see it as more of a pleasure."

Hegarty says that he now feels grateful for being transgender: "Expressively, emotionally, as an artist, as a singer." Still, there's a difference between a celebrated transgender adult and a transgender child – it must have been frightening growing up. "No," he says. "Because I was never anything else. It was just my nature. It was frightening what other people were saying – that I was going to eternal hell just because of who I was."

Perhaps this is why he seems increasingly drawn to subverting religious imagery in his work. Hegarty nods: "I'm interested in that mythology. I was raised as a Catholic, and I took it very seriously until around the age of 10, when I realised that it wasn't inclusive. I figured that out pretty quick: 'There is no seat for me,' not within that institution of religious thinking. There was only condemnation for people like me."

Momentarily, Hegarty sounds sad. "That's why I want to turn these things on their heads," he says, "Talk about simple ideas like Jesus as a girl, Allah as a woman, Buddha as a mother. I find the feminisation of spiritual deities, especially in the west, helpful. It restores a sense of balance." I wonder how all this would go down in, say, Middle America, but Hegarty seems unconcerned: "I'm so far removed from those circles; people don't notice me twittering on."

Several albums down the line, Hegarty says that he hasn't changed his attitude towards fame. He was shocked to win the Mercury prize for I Am A Bird Now and grateful for the New York apartment he was subsequently able to buy. However, he's scathing about capitalism as the universal barometer of success: "We don't go to a nun and say that her life has been a failure because she didn't create world peace; instead, she prayed in a room for 50 years. There are plenty of artists creating art for 50 years – whether or not capitalism rewards that work can't be the full measure of its validity."

How does he maintain a relationship with his fans? "I don't have a relationship with my fans," he says. "I feel I am in dialogue with culture generally. I have a relationship with the work; they have a relationship with the work. It doesn't mean that we have a relationship."

Hegarty feels that there are a lot of illusions about fame generally. "Fame doesn't change anything in your personal life. It's not like you're suddenly assigned five people who care more about you than they did before." For Hegarty, getting to work with the likes of Björk, Ono and Boy George are the real perks. "It's such a privilege," he says, suddenly looking quite shy. "That I would have the chance to collaborate with them – and they would see me as a peer – is just shocking to me."

Our conversation has come to a close. Quite apart from anything else, Abramovic is now wafting around the dressing room making fresh soup for lunch (she tells me later that she does this every day). Then Dafoe comes in and sits silently waiting for the soup. With them, Hegarty and I, and the candles, we're starting to resemble a performance piece by ourselves. "I think we're going to have to break here," says Hegarty sweetly, though I suspect he's relieved to get away from my germ-laden croaking.

Afterwards, the strongest impression I'm left with about Hegarty is of someone determined to be true to himself, whatever the cost. Indeed, before he leaves, to sing, beautifully, angelically, with his back to the audience, we get into a discussion about the job of an artist. Hegarty tells me that he believes artists have different jobs at different times. "Sometimes our job is to be contrary, sometimes it's our job to be whimsical. But sometimes…" He pauses thoughtfully. "Sometimes it's just our job to show up at a funeral and sing the funeral song, and express our joy at being alive."

The Life and Death of Marina Abramovic is on at the Manchester International Festival, 9-16 July (mif.co.uk). Antony and the Johnsons are playing at the Wilderness Festival on 14 August (wildernessfestival.com)