Maas, who had just graduated from Hamilton College in Clinton, New York, where she majored in creative writing, then set her sights on getting her work published.

In 2008, she took a massive step: She pulled her story off FictionPress.

"That was scary because until that point, the online world that I had built with fans was kind of a key part of my life and my identity. I built who I was and what I wanted to be based on how I interacted with my friends and shared my stories with them," she says.

"I was scared that if I took the story offline, it would all go away. The fans would disappear and what if it never got published? What if it became just kind of a sad story that I'd tell people, about how I was sort of semi-famous on the Internet a long time ago?"

But she adds: "I decided I wanted to be published more than I was afraid of any of the what ifs and any of the things that could go wrong."

She spent about 11/2 years "gutting the entire series", removing characters and plotlines, and adding news ones.

She met with a handful of rejections and, in 2010 - when Maas was just 24 - Throne Of Glass was sold to Bloomsbury.

The publisher would go on to buy the other novels in the series, which was last year optioned for television by Mark Gordon Company, the studio responsible for Grey's Anatomy.

Maas also juggles other projects. She has a second series, A Court Of Thorns And Roses, in the works.

Inspired by Beauty And The Beast, it follows 19-year-old Feyre, who is separated from her family by Tamlin, a faerie who can turn into a beast.

The first book was published last year and is poised to make its leap to the silver screen.

The next book comes out in a few months' time.

She also works on The Starkillers Cycle, an ongoing space opera she uploads on micro- blogging platform Tumblr with fellow writer and friend Susan Dennard.

These, says Maas, were a way to help her get through the publishing process - riddled with long spans of downtime as manuscripts were edited and books printed.

"I sound like a workaholic, but I'm the laziest person in the world, except when it comes to writing," she says. "With homework at school, I'd be like 'Eh, whatever.' But, every night without fail, I'd write, write, write."

Her mother, she recalls, would leave snacks outside her bedroom, which she would find only when she emerged from her room in the wee hours of morning, after a night of writing.

"My parents are my No. 1 fans, which is adorable, but also embarrassing. I wish my family wouldn't read my stuff," says Maas with a laugh. "Especially with A Court Of Thorn And Roses, which has a little more mature content. I've told them they can't read the second book because I won't be able to look them in the eye."

Maas, who gave talks at schools on her visit last week as part of Words Go Round, the Singapore Writers Festival's outreach programme for schools and the community, said she met students in Singapore who told her about their writing projects, from works of fantasy to contemporary fiction.

"These days, there are so many online forums and websites for aspiring writers to share their work that you're not really trapped in a bubble anymore," she says.

"There are people out there who will read your stuff. And that's kind of how I got my confidence as a writer. So it's like a wonderful development that was just beginning when I was a teenager and has now become this full-fledged enormous, environment."

Maas is not the only writer who cut her teeth with fan fiction. Others, such as The Mortal Instruments' Cassandra Clare and Jaida Jones of the epic fantasy Havemercy, have also been involved in fan fiction.

"I've always thought fan fiction is a wonderful way for aspiring writers to learn how to write and to find their own voice. Learning how to play in another writer's sandbox is a great way to build your own set of tools and learn about the ins and outs of writing," says Maas.

"Writing fan fiction was a huge part of me learning how to build a world, take characters and tropes and spin them. It's amazing now that there's Throne Of Glass fanfic out there. That is so full circle."

It is now an exciting time for young adult fantasy. For one thing, there is growing diversity beyond the "traditional European fantasy", says Maas, highlighting Roshani Chokshi's upcoming The Star- Touched Queen, inspired by Indian mythology.

Then, there is the growing prominence of women in fantasy - both as authors and as characters of heft.

"It's not just about writing strong female protagonists as physically capable women. It's about strong writing for women. Writing women who can have different types of strengths. Women who can be physically weak, women who can be pretty and own that beauty, women who can be ugly and are perfectly fine with that," says Maas.

"Different types of women who feel like people, who aren't being pushed into boxes. Every day, we're pushing the envelope and saying, 'We're not this and you can't put us into these boxes.'

"I love that young adult fantasy shows that there are no limits to anything young women can do."

• A Court Of Thorns And Roses, the first book in the series of the same name, and the latest book in Sarah J. Maas' Throne Of Glass series, Queen Of Shadows, are available from Books Kinokuniya at $17.66 each.