Vivid and Suspenseful
Will is on a quest to find secret Signs, so it should come as no surprise that a lot of the writing is suspenseful. We're given just enough clues to know something is happening without being able to figure it out. Check out this example:
He looked at Will, and Will looked back in growing alarm into the weathered face, the bright dark eyes creased narrow by decades of peering into sun and rain and wind. He had never noticed before how dark Farmer Dawson's eyes were: strange, in their blue-eyed county. (1.47)
This is super early in the story, and Farmer Dawson is cryptically telling Will about the Walker, but we're not sure what that means or why it will be important. One thing's for sure, though: We know it will matter—the darkness in Dawson's eyes makes it clear this isn't something of fleeting importance, but instead something of gravity (eyes are the window to the soul, after all). We just have to sort out the details, which is exactly what Cooper does throughout the book. She writes the novel in a way that keeps us guessing, while also keeps us hooked with its vivid descriptions.
When you read Cooper's words, you can instantly imagine what everything looks like because she paints a word picture for us. Check out how she writes about Will coming upon a door in the middle of nowhere:
Will thrust his cold hands into his pockets, and stood staring up at the carved panels of the two closed doors towering before him. They told him nothing. He could find no meaning in the zigzag symbols repeated over and over, in endless variation, on every panel. The wood of the doors was like no wood he had ever seen; it was cracked and pitted and yet polished by age, so that you could scarcely tell it was wood at all except by a rounding here and there, where someone had not quite been able to avoid leaving the trace of a knothole. (3.1)
See what we mean? We could draw a picture of that door, there are so many specifics about it. Cooper describes the pattern (zigzag), material (wood), and quality (knotholes) of the door, grounding us in this description before rocking our worlds with what greets Will once he enters. Just as her vivid writing helps us stay engaged amid so much mystery, it also gives us concrete things to hold onto among so much magic.