Hexwood by Diana Wynne Jones
I'm not completely convinced that Jones was in control of what she was trying to do here, but this is the kind of novel that you'd have to reread before really having read it, if that makes sense. It's a story about story-telling at it's root, I think. Not a story about stories (or meta-story) as I thought at first, but a story about story-telling.
It's science fiction, but it's science fiction married with fantasy. There's a galactic civilization and advanced technology, but most of the action takes place on Earth in an Arthurian setting with magic and dragons. The driver of the story is a machine called the Bannus (great name, is it derived from something?) that's described as a machine to aid in decision-making. The way it works is to take a basic scenario and run through all the alternative versions of it to help people choose which one they prefer. Thus a story-telling machine. What decision it is trying to help the characters in the novel make is complicated and involves spoilers. Likewise to discuss the characters themselves is difficult, because most of them aren't who they seem to be at first and appear in multiple guises as the Bannus works through various versions of the scenario.
The first part of the novel leaps between different versions of the scenario and is extremely disorienting. As the novel progresses, more and more characters are added to the mix (or so it seems), and everything just gets more and more complicated. Ultimately the plot is a very familiar one, but the multitude of versions on offer (sometimes only in brief glimpses) is what makes the book extremely difficult and dense.
One reason I'm not completely convinced that Jones was in control of all this is that the ending felt like a lot of people explaining to each other what just happened. Then again, if it's a story about story-telling, maybe it's appropriate that the resolution consists of a lot of people telling more stories. Yet the other thing that felt slightly off about the ending is an apparent attempt to make it all about the titular forest, which to me felt disconnected from everything else -- and a bit of deus ex machina (or ex sylvanus, or whatever the Latin for forest is) -- but could well make more sense on a reread.
It's a very strange book, and I liked that about it. Once again the characters are very engaging, although perhaps slightly less so amongst some of the minor characters (even Hume, who isn't really minor) than in the other two Jones books I've read. As in Fire and Hemlock there's the presentiment of a romantic relationship between a younger girl and an older man (but not much older) that isn't what it looks like at first but still inhabits uncomfortable territory in what feels like a weirdly realistic way. Once again Jones unleashes her imagination into unexpected and risky corners and byways. I really admire that about her. Her stories feel alive, conflicted, writhing and wriggling in your hands and in your mind. You're never quite sure which way they're going to squirm.