Ok I've got a style question regarding exposition. How much exposition do you need for a fantasy novel to set the scene. I don't want the first 20 pages to read like a text book, but there is a certain amount of "These are the factions, this is the problem, here is how we got to this point, this is why these two hate each other" That has to be done in an any book where the world is an unfamiliar one.
The key is to intersperse the exposition. At times, you'll have to grin and bear it and just do an info-dump but the best way is to feed it out slowly. Nothing slows down a story faster than too much information. As a general rule, don't write more than two paragraphs of exposition without breaking it up. A little dialogue, some action (even if it is just ancillary, like walking around the room), and changes in emotion are all viable breaks for exposition blocks.
One of the mistakes that I always made early on was feeling like the story wouldn't work if I didn't tell the reader everything right away. I have since learned that the opposite is true. In your attempt to feed out the information slowly, the reader will have questions as to why it works that way, who is this person, where does this take place. Questions keep a reader reading--
so long as those questions are answered at some point. For basic questions, like who is this character? try answering it within a chapter (unless you want to keep the reader guessing). Where does this take place? can be answered slowly throughout the whole story, as can how does magic work. Even if you don't explain, if you can
show the reader that magic does work, you don't really ever have to explain it!
To go back to your question, I'd say about 30-40% of a modern fantasy novel goes toward world building. In a perfect world, I'd say no more than 15-20% should be dumped as exposition, the rest should be interspersed.
"Mark gritted his teeth, the last time he trusted an ambassador from Kreel the city had been attacked and twenty-thousand people died. The armistice was meant to stop that from happening again, but Mark would never trust the Kreel to honour their word. War would be inevitable, the Kreel knew it, and Mark knew it." -- This is exposition, cloaked in action. We learn so much from a sentence like this, yet it doesn't feel like an info dump. Using your example, this short phrase tells us there are two factions, with a problem, how we got to this point, and why they hate each other (well, sort of). All of this is general and needs to be built on, of course, but it didn't take 20 pages either. Now that the stage is set, the reader will keep going to discover the rest of the story. You'll be able to expand on all of those points throughout the book, but the basic
need of the story has been met.
I hope this helps.
