Since I'm not familiar with the 'dark rise novel', it's hard to say exactly. However, it's common in such novels to have a main character who has some special ability or connection that makes them crucial in the fight against the rising darkness. There could also be characters who are initially on the fence, not fully committed to either side, but are eventually drawn into the conflict as the story progresses.
There could be a trainer who has a special bond with dark Pokémon as one of the main characters. Maybe also a Pokémon researcher who is trying to understand the sudden rise of dark Pokémon. Another possibility is a powerful dark Pokémon that plays a central role in the story, with its own personality and goals.
It's possible that the main character is a Pokémon researcher who is intrigued by the sudden rise of dark Pokémon. They might study these Pokémon, their behaviors, and their habitats. Along the way, they could encounter other trainers or Pokémon enthusiasts who either help or hinder their research into the dark Pokémon's rise.
In the 'rise of the dark lord novel', the main character is likely to be the dark lord. However, there may also be characters like his minions or followers who play important roles in his rise. On the other side, there could be a wizard or a knight who tries to stop him, and they would also be main characters in the sense that they drive the plot in opposition to the dark lord.
Perhaps there is a young and ambitious trainer as a main character. This trainer might start with a single dark Pokémon and through various adventures, build a team of strong dark Pokémon. There could also be a professor - like character who provides knowledge about dark Pokémon and guides the trainer on their journey. Another possibility is a rival who also has an interest in dark Pokémon and constantly challenges the main trainer, driving the plot forward.
The dark lord himself is obviously a main character. There may also be a young hero or heroine who stands against him.
Typically in such a story, there would be a hero or heroine. This character would be courageous and determined. There might also be a wise old mentor figure who gives advice on how to deal with the Snow Queen. And of course, the Snow Queen herself is a main character, with her cold and powerful presence.
I'm not familiar with the exact details of this fanfiction, but typically in a Harry Potter - based fanfiction with a 'rise of the dark angel' theme, Harry Potter himself would be a main character as he is the hero of the original story. The 'dark angel' would be another crucial character. There might also be other characters from Hogwarts like Dumbledore, who would oppose the rise of the dark angel. Maybe some new characters created specifically for this fanfiction would also play important roles, perhaps characters who are related to the origin or the power source of the dark angel.
In 'Rise of the Phoenix Novel', it's possible that there is a group of characters. One could be a creative type, like an artist or a writer, who has lost their inspiration. Another might be a warrior - type character who has been defeated in battle. Together, they support each other on their journey of rising again. And there could be a mysterious figure that appears throughout the story, providing cryptic advice that helps the characters on their path.
In 'rise of the guardians novel', the main characters are quite diverse. Santa Claus, also known as North, is a large and jolly figure. He has his workshop at the North Pole. The Easter Bunny, or Bunnymund, is a feisty character with a strong connection to nature. Jack Frost is a young - looking spirit who controls ice and snow. The Tooth Fairy, with her fairies, is in charge of collecting teeth and keeping the memories associated with them. And Sandman, though he doesn't speak, communicates through his sand creations. These characters must work together as guardians against Pitch Black.
I'm not sure as I haven't read the specific 'in the dark novel'. But usually in such novels, there could be a protagonist who is often at the center of the story, facing the challenges presented by the dark elements. There might also be an antagonist, someone or something that is causing the problems or the 'darkness' in the protagonist's life.