Where do characters come from?

I'm always interested in where characters come from. Sometimes you read a book and a character stays with you for a long time afterwards - from Lyra to Lizzie Bennet, Frodo to the father in The Road.

There's a kind of magic when a character arrives in your head with flesh already clinging to the bones. J.K. Rowling famously said that Harry Potter arrived on a train she was travelling on. She had to rush and write things down before she forgot any details.

Certainly I've had this experience of someone appearing in my head fully-formed. It's like a kind of magic or a gift from a strange little corner of your mind. One of them was Evie in The Watchers. She arrived, complete with troubled background, one night in February and I scribbled some notes in a book. She caught my imagination but I didn't get a chance to write about her until June. There was a sort of urgency about her that helped drive me through writing the book. Interestingly the few people who have read The Watchers in draft have all cared about her and found her likeable and believable. Gillie said that she has a kind of integrity that makes her compelling. Maybe this is because she felt so real when I was writing about her.

I can think of two other characters I've written about in half-finished books who 'arrived' fairly randomly. One appeared in a 'picture' in my head - a man sitting in the woods around a fire, with a teenage boy and girl beside him. The other arrived as a name and a sense of who she was and who her opponents were. They're both characters I want to come back to in time.

Of course the problem, as ever, is time. So no more blogging tonight! Time to do some storytelling!

And if anyone is feeling bored... who is the girl in the picture? What's her story?