Apple is perplexed by the adoration heaped on her since the release of Tidal, her Grammy award-nominated debut album. "When I see kids my age screaming my name, I feel ridiculous. I think, 'Wow, five years ago you were calling me a dog.'"
Today, she is a bona fide beauty, splashed over five pages of The Face, gazing, wide-eyed, from Rolling Stone. Her heavy-rotation MTV video for "Sleep to Dream" has her in her vest and knickers. The station preludes it with the message: "Warning: Teens in underwear". Apple is the geek as sex symbol (two of her close friends, Winona Ryder and Sara Gilbert - Darlene in Roseanne - have also found themselves signing autographs for peers who previously harassed them).
"I do think I'm pretty," she says. "Right now, I think I am. When I feel bad about myself, it's because I feel I was made wrong. I was named the dog of my school, and that stuff stays with me. I tell people I was an ugly kid; then I see pictures and I really wasn't."
No matter how mature her lyrics may be, she is still a teenage girl, and having her photo taken makes her feel deeply uncomfortable. The pictures in The Face, in which she wore smudged black kohl halfway down her face, a yellow dress and a furious scowl, portrayed her as some sort of tortured artiste crossed with Veruca Salt. Her glossed pout seemed to demand heroin and hair ribbons.
"They smeared that stuff on my eyes without me realising. The photographer called me a few days later almost in tears because he felt so bad. There is a hair person that wants everyone to open the magazine and say, 'Who did that hair? Let's use them.' Everyone wants you to be a blank canvas. At one photo-shoot, I felt like a hotel room, like they just mess you up and leave you there."
Like all the great miserabilists, from Bob Dylan to Leonard Cohen, few give her credit for how funny she is, if very dark: "You say love is a hell you can not bear/ And I say gived me mine back and then go there/ For all I care," she snaps on "Sleep to Dream". She has been described as the new Alanis Morissette, but Apple is in a different category from all those women who use Joni as a text-book for their career and Joni alone. Tidal is a 21st-century blues record. Between songs, she bubbles away like a kid in a Woody Allen film. "I just wanted to thank the boy who left me the ring. It's lovely. I'm not wearing it because I'm so nervous and goofy I know that I'd cut myself. I wore a pendant on stage once and I nearly knocked myself out."
Striding out from behind the piano to sing "Sleep to Dream", the insecurities vanish. The dog of her school writhes like Kate Bush. Tugging at her tiny tank-top and flicking her long hair, she makes slow circles with her hips. It is sexy but also uncomfortable, because we know her history. When she was 12, Fiona Apple was raped by a stranger who broke into the family apartment.
"It bothers me to be identified by that one incident, because there have been so many other incidents that have contributed to the person that I am," she says. "The first time I said it, I knew that it would be hard to shake. But someone asked me something and the fact that I was raped was relevant to the answer. I thought, 'If it's something that I want to say but I don't, what does that say about how I'm handling it?'"
In the depths of her unhappiness, Apple was given a compilation of Maya Angelou's poetry.
"I slept with it under my pillow every night. Maya Angelou is so honest about her weakness and about times in her life when she has been humiliated. On the back is her photo. You could see in everything about her - her posture, her smile - that she is so proud of herself. It gave me hope. If we had the same feelings of weakness, we could also have the same feelings of pride."
Singing Angelou's poetry to herself, Apple decided that she was meant to be a musician ("If I couldn't have my place in the world, I would have gone to Hawaii and been a potter on the beach"). She could have her place, and quicker than she imagined; she gives a demo tape to a friend who was babysitting for a woman who had a party and played a tape to Adam Slater, now Apple's manager and producer.
"My dad and I went to meet him, and Dad kept saying, 'Don't expect anything', but we left and both said, 'That's the guy.' He was my manager first, and he only became my producer because we had been hanging out so much and knew each other so well. We said, 'Why are we going to hire some producer to come in here and dictate how I should sound?'"
The record deserves its plaudits and not just, as the music papers keep gushing, because the writing is so mature. Fiona Apple being admired for sounding older than 18 would be like Gwyneth Paltrow winning an Oscar for not sounding American in Emma. In her eloquence, she has made people realise that these are not "grown up" feelings and experiences but human ones that teenagers also have a right to. It's because she is so completely a teenage girl, with the sense of unfairness and desire that made Morrissey's best work. We live in a culture of cool: "You have to be calloused and tough and never have a moment of vulnerability." Yet the boys in the Pearl Jam T-shirts, who have known nothing but mosh pits and beer parties, watch the gig in silent reverence. Even the PR girls in the red leather trousers have the grace to turn off their mobile phones.