Once I'd worked out that I couldn't possibly expect people to enjoy a monstrous, 3000-page book, I realised I could in fact create a labyrinth of a story with four different points of entry. But what interested me was creating something that would rearrange itself every time you read one of the other books. So depending on which order you read them, the implications and angles would change. To get that right, each one of the books had to have its own personality and texture -- even though they are connected, they are very different creatures.