Evil exists in us all, Torak. Some fight it. Some feed it. That's how it's always been.
Changing from biochemistry to law was easy because I was rubbish in the laboratory. I could never decide how much to put in a test tube because I'm not very good at maths.
At university - when I was supposed to be studying biochemistry - I had tried to write a children's book about a boy and a wolf cub, and there was a paragraph in that which was from the wolf's point of view.
I hate it when you see in films people with their anoraks flapping open in a blizzard. They'd be dead in a couple of minutes. It's got to be real. It's got to work.
I've climbed Stromboli when it's erupting, which is quite a heavy climb: three hours with a helmet to get to the top. When you're there, and it's dark, and you can see this eruption and feel it, it's quite different to watching it on TV.
I'm quite happy trekking around Greenland on my own, but those big book tours in America or the Far East are the only time I ever really feel lonely.
It's true to say that once I've got the bare bones of a story, I often get ideas from my own research trips to faraway places.
To experience the northern forest in the raw, I went to northern Finland and Lapland, travelling on horseback, and sleeping on reindeer skins in the traditional open-fronted Finnish laavu. I ate elk heart, reindeer and lingonberries, and tried out spruce resin: the chewing gum of the Stone Age.
It's the little details I love. How to fletch your arrows with owl feathers, because owls fly silently, so maybe your arrows will, too. How to carry fire in a piece of smouldering fungus wrapped in birchbark. These are the things which help a world come alive.
To get the feel of the polar night, I went back to Spitsbergen in winter. I went snowshoeing in the dark and experimented with headlamps and climbed a glacier in driving snow.
The most remote place I've been to was in Greenland. I remember setting out for a solo hike from a small cabin, itself several hours' boat ride from the nearest settlement.
My thirties merged into my forties, and I sort of gradually realised that I don't really want children. Now I'm glad I don't have them. Part of that is because I have my books.
I saw myself as a trailblazer in the 1980s as a female lawyer in the City. It was exciting, as women were outnumbered by men five to one. But while I had this sense of trailblazing, in reality, I wasn't pushing boundaries; it was just a personal myth I'd created, as I was doing a job I wasn't enjoying.
When my father was diagnosed with terminal cancer in 1991, I asked him if he had any regrets, and he said no. I was a burnt-out litigation solicitor in my thirties, hating my life, and his cancer made me re-evaluate it all.
I wanted to write a very simple story about a boy, a wolf, a girl, a bear and a forest, so I thought I might set it in the past. I didn't realise that it went back to when I was 10: I used to love the Stone Age when I was a kid and wanted to live in it, and I got rid of my bed and slept on the floor, but I didn't remember it.
Why do so many children love the idea of being snowed in or shipwrecked, of having to survive on one's own? When I was a child, I was no exception. I wanted to hunt with a bow and arrow like the Stone Age people: to skin deer and build my own shelter. And I desperately wanted a wolf. As we lived in London, my options were limited.
For a novelist, the great thing about the Stone Age people is that we know virtually nothing about their beliefs - which means that I get to make it up! But it's still got to be plausible.
My novel 'Wolf Brother' is set in northern Scandinavia during the late Stone Age, so I was aware from the start of Norse influences. I used some Norse names, and the soul-eater Thiazzi is based on the Norse storm giant, Thiassi.
