That's right. In any writing you'll always have the X-FACTOR.
Dun dun dun!
Definition: a circumstance, quality, or person that has a strong but unpredictable influence
Now this isn't JUST for fantasy writing, my lovely readers. This is for any writing. What is the unpredictability?
In my fantasy world, I'd have to say it is the area around old Argisindya, where, after the city was destroyed, magic went "mad". If I were to pick a person, well, that would be the entire Li'endrin bloodline. Minus Alabassin. He's such a sweet boy.
The unpredictable is something that keeps your readers hooked. I love tossing in that x-factor. The thrill of knowing it is going to shock the reader, that's just downright awesome.
Do you like to be predictable or unpredictable in your writing? What about in what you are reading?