Since I don't know the exact 'Christmas Trolls Story', the main characters could be the trolls themselves. There might be a leader troll who makes decisions for the group.
Trolls themselves are the most common characters. They can be of different sizes and temperaments. Sometimes there are also human characters who are the victims or challengers of the trolls.
Poppy is likely to be one of the main characters. She's always positive and loves to spread happiness. Branch, who is a bit more cautious, might also be a main character. They are important in the Trolls world and would play big roles in the novel.
They might get really excited and start comparing it to their own experiences in the Trolls world. Maybe they'll laugh at the funny parts or feel inspired by the creative interpretations in the fanfiction.
I think Poppy and Branch are the main ones. Poppy is usually very positive and outgoing, while Branch is more cautious. In the junior novel, they would likely lead the adventures during the world tour.
Well, in fantasy fiction, cave trolls differ from other trolls in several ways. For one, their physical features might be more suited to cave living. They could have a thicker hide to protect against cave - related hazards. In terms of behavior, cave trolls are usually more territorial about their caves. While other trolls might be more nomadic or have a wider range of movement. Also, the diet of a cave troll is likely to be more limited to what is available in or near the cave, such as bats or underground fungi, as opposed to other trolls that might have a more diverse diet depending on their habitat.
The Trolls origin story is that they come from a magical land filled with music and color. They are small, furry creatures with a love for fun and celebration. Their world was once threatened by the Bergens, who saw the Trolls as a source of happiness (which they could gain by eating them). But the Trolls managed to survive and keep their positive spirit alive through their music and unity.
In most cases, it is legal to watch Trolls fanfiction. Fanfiction is a form of creative expression by fans, and as long as it doesn't violate any copyright laws in terms of using original characters inappropriately or stealing the main plot of the official work, it's okay.
Most likely, Harry Potter himself would be one of the main characters doing the trolling. Given that it's in the title, he's probably at the center of the humorous and mischievous actions.