Interview: Joanne Harris, author

Harris, rather unexpectedly, identifies with him. "I feel close to BB," she says. "He represents the part of us that really would like to kill a relative, get away with it, and have no remorse. It's nice to access that from time to time. We're all potential murderers. The only thing that separates us is circumstance and opportunity."

What you see isn't quite what you get with Harris. She looks and talks like a teacher – she has a quiet-at-the-back-of-the-class manner – and was indeed one for years in a Yorkshire boys' school. But this neatly turned out 45-year-old with a black thicket of cropped hair and a piercing gaze is clearly a rebel in disguise. She plays bass in a band, writes anonymous "fanfic" (or fan fiction) online, and ran the Dungeons and Dragons club at the school where she taught, gaining a reputation for dabbling in the occult. "Oh bless, that was from the head of RE," she says. "Mad as a fish. The school was all rugby and cold showers. All the freaks joined my club and we had a great time, dressing up and taking rubber swords into the woods."

It's all a far cry from the dreamy, truffle-stuffed sensuality of her breakthrough novel, Chocolat, which spawned a major Hollywood film, a friendship with Juliette Binoche ("she slept over a few times and we cooked together") and the unlikely genre of gastromance. But Harris has written 10 books since then, many of them strange, and blueeyedboy is her most sinister yet, more Black Magic than Dairy Milk.

Written in the form of a series of blogs by the titular blueeyedboy, or BB, some are public, posted on badguysrocks, his website for potential murderers, and some are restricted. Some are based in reality, about his troubling history with fellow blogger Albertine and his relationship with his terrifying mother and two brothers, and some are pure murderous fantasy. All have an accompanying mood status and a playlist.

"BB exists with his iPod in all the time and therefore his life has a soundtrack," Harris says. "I'm the same. I love the thought that someone can be talking garbage to you and you can't hear them because you've got Jarvis Cocker singing I Will Kill Again in one ear."

It's experimental stuff and certainly not an easy read. There's a proper headscratcher of a twist and it's not giving away too much to say I didn't have a clue who was dead and who was alive at the end. Harris is delighted when I tell her. She describes blueeyedboy as a Rubik's cube and calls it "the most messy, difficult book I've written". It was borne out of a year of feeling unable to write at all. "I was involved in a rather bitter wrangle with my agent," she says. "It was about other people, money, politics, things about which I knew nothing and had little interest. We ended up with a very messy agent divorce. I didn't write for a year. I was burnt out."

Harris found herself passing the time online, co-writing a 400-page piece of chain fan fiction on the Byzantine US cult series Lost, and making virtual friends that she thanks in blueeyedboy's acknowledgements. "I found these communities, and that's what links all my books," she says. "An interest in the chemistry of small communities. It was only going to be a matter of time before I started considering virtual ones. I found the intensity of online relationships fascinating because they're based on trust that these people are who they say they are. Why should they be? I was corresponding with one woman for two years before she told me she was blind."

Eventually ideas began to percolate. A taxi driver she met in Naples, who had grown up in a family where each sibling had to wear a different colour, became the inspiration for BB. Years earlier Harris had started another novel about a blind girl with an artist mother and abandoned it. Now she started to make these two characters talk to each other through blogs. "It seemed to fit," she says. "I wrote it out of sequence and it remained mysterious to me even as it developed. It was certainly an angsty time and that came out in an angsty tale. I've always filtered through fiction what is happening in my life. When I was writing about a woman alone facing an intensely patriarchal system in Chocolat I was teaching in a boys' school surrounded by men. Perhaps this book, which is about feeling oppressed, may have mirrored certain aspects of my life." She raises her eyebrows, letting me read between the lines about her ex-agent. "It doesn't surprise me that a difficult story came out of a difficult time." v

Blueeyedboy is published on Wednesday by Doubleday, 18.99, hardback

This Article was first published in Scotland on Sunday, March 28, 2010