Image caption Banks: "I just needed to get all these thoughts out or I was going to go crazy."

Her first song only came out in March, but Los Angeles singer Banks has already gained a devoted fan base with her moody, intimate brand of R&B. She tells the BBC about the "overwhelming" response.

"I signed my first belly last week!" laughs Banks, sipping tea on a brisk autumn day in London.

"Oh my God, it was fun... But pens weren't meant to write on skin, is what I'm learning.

"I haven't caused any injuries yet - but my signature didn't look very good sometimes."

In a short space of time, Banks has captivated anyone who's stumbled across her entrancing, feminine take on the downbeat R&B of Drake and Frank Ocean.

Image caption The singer recently received her "first piece of fan art" and shared it online

The 25-year-old has been branded "mysterious", mainly because she doesn't engage with Twitter or Instagram ("my management run that stuff," she explains matter-of-factly).

But fans can get in touch in a more unusual way. She lists her mobile phone number on Facebook, stating: "If you ever want to talk, call me".

"Some may call me naïve or stupid," she says, "but I haven't got any creepy text messages or calls.

"It's just been people that want to send love and say how much the music means to them."

She pauses for a second to reflect.

"This time last year I was writing in my room, on the floor. This is so cool, everything."

'Dark time'

Banks is her surname - her friends and family call her Jillian.

She started making music aged 15, when a friend gave her a keyboard to distract her during "a really dark time" at home.

Amidst the normal turbulence of being a teenager, her parents had started fighting, and were later to divorce. "It was really overwhelming," she says.

Image caption "I want to create a really dark atmosphere," says Banks. "I want it to feel heavy."

"You don't have the tools at that age to really know how to work things out in your own head.

"I felt very alone and helpless. I didn't know how to express what I was feeling or who to talk to.

"Then somebody gave me this toy keyboard as a gift. It wasn't a really high quality one, the keys were lighter than a napkin, but I started messing around with it and these melodies came out... It was like five pounds of gravity was lifted off me.

"It was almost my little secret. Once I discovered it, that whole year I was just in my room with the door shut.

"It sounds like a dirty typical teenager, but it wasn't!"

For years, Banks kept her music private "because it was such an outlet for me". She enrolled in university, earning a bachelor's degree in psychology. Then she took a deep breath and started to let other people hear her songs.

By the start of this year, she was talking to a few record companies - "no papers had been signed" - when suddenly one of her songs appeared on the radio.

Before I Ever Met You "was on a private Soundcloud page and all of a sudden Zane Lowe played it on Radio 1," she recalls.

"I didn't even understand how he got it. It was really crazy and amazing. It felt like a gift from the universe."

Bruised and brooding, the song's darkly dealt R&B ("I never knew I could be broken in so many ways") was streamed 250,000 times before the ink dried on her record contract.

"The response I got was exactly what anyone would want if they'd written a song. People really connected to the words and the sound.

"There are no words to describe what it made me feel."

But the reaction was no fluke.

Working principally with British producers (Lil Silva, Jamie Woon, Totally Enormous Extinct Dinosaurs) Banks has released a series of enchanting, sultry pop songs that tug incessantly at the heartstrings.

Image caption Banks's videos have the same brooding intensity as her music

Fans obsess over every new release, drawn as much to the lyrics as the magnetic, pulsating grooves.

Under the video for Fall Over, YouTube user Haley Friesen commented: "This song is beautiful... This is how I feel with guys that I trusted too much".

"This song makes me want to dance and cry," wrote "xXnhbXx" below Waiting Game. "It expresses all my feelings."

Catharsis

The reception is overwhelming. "It touches every pore in my body when I hear that," says Banks.

"A lot of times, people are ashamed of feeling weak and being rejected - so it's liberating to be able to sing about those things. And it's amazing when other people don't feel alone because they hear it."

The singer may only be 25, but she certainly seems to have been through the emotional wringer.

On Change, her lover's mood swings leave her in tears but he "says it ain't your fault because you had an emotionally abusive daddy".

Image caption "When I'm writing, I don't listen to anyone else's music," says the singer

On her latest single, the hypnotic This Is What It Feels Like, she confronts someone who pulls away every time the relationship starts to get serious.

" I can see all the things that imply you're secretly in love / And finally when I let myself fall hard for you / I see you trying to pretend like I'm making it up," she sings.

In the video, Banks' emotions are so intense she generates a furious thunderstorm outside her house.

"Yeah, I've had some experiences," she says, coyly.

"When I love somebody, I love them. When I'm sad about somebody, I'm really sad. So that's what I write about: The dynamics between people."

She adds: "My parents are divorced and seeing that was really painful for me. Really painful for me.

"But that's also a big part of why I'm intrigued by the dynamics between people - because I was close to something that fell apart."

Speaking to her, you get the impression Banks' songwriting is more about catharsis than seeking stardom.

"Oh my God, yes," she says. "It would be a scary world for me without it.

"It's air and blood. It's everything."

Banks's London EP is available now and she is touring the UK with The Weeknd from Friday, 22 November.