In my fantasy novel, (wood, meadow, and ocean) fairies, trolls, and witches seem to be the main characters.

Apparently, the trolls are important, though I don't know why yet. They aren't a main character. Though they may be a main side (or hidden nonspeaking) character. Not to say they can't speak, they can. They even have their own service window at the bookstore! That was important enough for chapter 4. And later, with some of the history.

How could a troll have helped save the forgotten books of knowledge? On purpose? By Accident? And whom among them today knows where they are hidden, and how to reach them? What traps await them?