AL Kennedy: 'I don't think happiness is fatal. You have to write from some kind of joy'

As popular as she is on the Scottish book-festival circuit, trouble seems to follow AL Kennedy from tent to gusty tent. On her way to last year's Wigtown festival on the remote west coast, it became clear that her cabbie was heading for Wigton in Cumbria. She arrived an hour late, with steam coming out of her ears, and then her microphone broke. "I could shout," she suggested. "I'm in the mood." This year at Ullapool, she became reluctantly involved in the rescue of an unwilling gannet. "Of course, just outside Ullapool it dies, so I've got this rapidly stiffening, massive bird, and it looks like I've murdered it..." A consummate story-teller, Kennedy turned both these mishaps into instant comedy and left her audiences sorry for her, amused and slightly in awe. Tickets for her appearance at the Edinburgh Book Festival on 21 August look likely to be a good buy. Previews for Words, her one-woman show at the Assembly Rooms, have gone "really well", she says, adding gleefully: "We're already making people cry."

On paper, Kennedy is even more popular than she is on stage. Reviews of her last book, Day, called it "a virtuoso performance" and its author "a writer of enormous power". But tell literary journalists that you're planning actually to interview her and they all pull a particular face. It is pity mixed with schadenfreude and something that says "more fool you". For Kennedy, everyone knows, hates reviewers, and considers the interview process a depressing waste of her time and newspapers' space. The excoriating "reviews of the reviews" that she posts on her website are just the thing to make book reviewers wince. A profile that I wrote of her when Day won the 2007 Costa Prize is quoted on there. I said it would be a shame if Kennedy were to "climb out of her Eeyore costume". She wrote: "The rumours of my dressing up as a donkey have been vastly exaggerated."

So, when she arrives at the Park Inn in Glasgow, to spare me an hour between rehearsing her show and researching her new novel, she is a surprise. She doesn't exactly have her Rebecca of Sunnybrook Farm costume on (in for a penny, in for a pound); but rumours that she is bad company or fundamentally uninteresting – just a "workaholic who occupies most of her time with numbed travel, events and caffeinated typing" (her words) – are themselves vastly exaggerated. It could be an elaborate scam to avoid interviews. Lots of writers would rather be writing than telling a person with a tape recorder about the chair they sit in to write. (One specially designed to relax her bad back; there are pictures of it posted on her website so there's no need to ask her again.) But then she goes and blows her cover by being all self-effacing, easy company and fun. "Could you stand it if I had a tuna sandwich?" is about as difficult as she gets. She later admits that it will probably be all she eats all day.

As frustrating as it may be to Kennedy – Alison Louise, but again, don't ask! Or try calling her Almond Ladybits, as she suggests as a joke – reviewers struggle because it is much harder to review very good books than bad ones. And her new collection of short stories, What Becomes, is yet another exceptionally good book. Each one a different answer to the question "What becomes of the broken-hearted?", the 12 stories are necessarily bleak, but also engaging, hopeful, sorrowful or funny. One, "Sympathy", is written entirely in dialogue, between a man and a woman having less-and-less anonymous sex in a hotel room. Many, including the fabulously titled "Whole Family With Young Children Devastated", are about being single. Almost all of them involve blood, recalling Vasyl, a character in Day. "I understand people," he said. "They hold blood. That's all they are."

Kennedy's research for her next novel, which she is keeping under wraps, sounds a lot more fraught than her preparation for Day. "I don't normally do research with people who are alive," she says. But in the week before we meet, she has interviewed "some of the loveliest, loveliest people ever and some of the most vile people on earth". One of them was so unpleasant he has caused her back problems to relapse. "I was trying to get images of attractive people," she winces. "And nothing was coming. Even picturing David Tennant wasn't working. He kept going all blurry. It was awful."

In a cautious way, Kennedy is curious about people. But it seems to be her burden in life that mostly nutters are curious about her in return. "I get a lot of stalkers," she says. "One of them had allegedly done some quite unpleasant things to somebody and the police were involved. But you do have quite an intimate relationship with people that you read because they're in your head. So I can understand that there is this thing... I mean, I once inappropriately touched David Tennant in a shop because he had a familiar face."

Then there are the people who come to her stand-up comedy. "There's bound to be somebody mad sitting over there... stage left towards the front... because that's where mad people sit. [At a book festival it's]: 'Hello. I've never been published and I've sent off 35 unpublished manuscripts and it's a conspiracy and I'm wearing a transparent mackintosh with no pants...' They're a bit left and to the front, too. Although my audiences are all a bit left and to the front. And we love them." Obviously, though, they're not as bad as the journalists. "Oh, you know when a journalist is in," she shudders. "They always sit in the front row and they just look like a statue from Easter Island that you've really offended."

For someone who claims repeatedly that she doesn't read her reviews, or newspapers, or watch TV, Kennedy knows a lot about her critics. When she suddenly came out as a stand-up comic, "a number of journalists hated me heartily for it and have given me all kinds of dreadful [criticism] for doing it," she claims. These bad reviews are actually quite hard to find among the praise. Equally, Kennedy seems as uncomfortable talking about praise as she is happy to dissect her critics. She recalls being touched when a lady in a plaster cast hobbled over to her on a train and left a note saying (and here she mumbles), "I like your work." When she talks about winning the Costa Prize, she is almost embarrassed. "Well, it made research easier because you can say, 'Um, er, I'm AL Kennedy, Costa Prize winner. I'm not just a random lunatic; I am a random lunatic with a prize.'" She hasn't spent the £30,000 prize money yet, she says glumly, so it's still in the bank not earning any interest.

It begins to seem that misery is an essential part of AL Kennedy. I was surprised to read that she likes Scissor Sisters, so I ask which is her favourite song. "Oh, what's the one about death?" she ponders. "'Intermission'. Love that. It makes me laugh like a drain." She would be quite happy on a desert island, she insists, but she'd be lost without paper, and she might miss people "spasmodically". So what would happen if David Tennant turned up in Glasgow, touched her inappropriately and taught her what really becomes of the broken-hearted? Would it be the end of the dour, funny AL Kennedy whom we love even though she hates it? No more stand-up comedy about her tragic single life? No more beautiful novels packed with insight and pathos and loss?

"Oh noooo," she says, "I don't think that happiness is fatal. I think you have to write from some kind of joy... I've seen people who are long, long-term single and I really like their work and then they finally get somebody and I still really like their work. It's just kicked up an energy level."

I take it all back, then. Lovers of literature, hold hands and make a wish that Kennedy climbs out of the Eeyore costume, dresses up as Rebecca and skips off to Elsinore with Doctor Who. Her writing would still be dazzling. And I'll take whatever she throws at me for saying it.

The extract

What Becomes, By AL Kennedy (Cape £16.99)

'...He'd be the cheap motel breed of adulterer. Not for interesting and perverse reasons – just to save cash.

Fair enough, his wife is a dead-eyed, organic hummus-producing marionette with a whispery, creepy laugh – but he'll have made her that way. And she'll have made him a sticky-handed fraud reliant on alcohol, golf and non-threatening porn. They are every excuse they could ever need to abscond and yet they'll stay and, having ruined themselves and each other, they will grind on and on and their son will be worn down and hollowed at seventeen...

Hope not.

I'd like to think he'll muddle through...'