Normally you wouldn't care for reading information on Trolls, but for some reason the cover of the book drew you in. Not only did it have various types of Trolls on it, but it included females as well, which was weird in its own right. Not to mention it was the size of an encyclopedia.
You decided to go through the introduction first before making any major decisions. It gave an explanation of explaining trolls in and various forms of media they appear in. The book itself would discuss most, if not all of them to various degrees. Usually Trolls were dumb ugly, but it pointing out 3 types primarily.
1. Fantasy Adventure Trolls: These were often huge hulks of destruction that various adventurers in fantasy would come across. Differentiating them from other hulks of destruction like Ogres, Giants, and other such monsters, Trolls were often seen in swamps and have various forms of regeneration, with weaknesses to counteract it. They also tended to be more lanky than bulk, but the book reminded it would go into more detail later.
2. Fairy Tale Trolls: There was some overlap with Fantasy Adventure Trolls here, but this often dealt with Trolls who had more regular interactions with humans. The common "Troll Toll at a Bridge" was the most common one, but this could include Norse Mythology Trolls as well.
3. Misc. Trolls: Trolls made for Toys. Trolls as one off horror movie use. Trolls for cartoons. Why didn't these fall under the above two categories? They often shared no common traits other than being ugly to some degree. They could even be smaller than humans and not much monstrous content to them.
You went through more of the introduction and decided the book caught your interest well enough to check it out. After a quick visit with a clerk and stamp, you were on your way home with the book on your mind.
At home you spent all your waking hours with little breaks reading through all of it. It was a massive book, but you kept reading as much as you could. It was incredibly detailed with pictures, biology, and even behaviors of each one. This could've been a science book if itself didn't keep reminding of the stories and fictions the Trolls came from.
At some point you fell asleep. In your dreams, a certain type of Troll stood out...