The Grand Elder of the Namekians could also be a significant character. He could see some sort of potential in Percy and send him on a special mission. And perhaps there's a female Namekian who has a special ability to communicate with nature, and she teams up with Percy to protect a sacred Namekian forest from destruction.
It might be a story where Percy discovers he has some sort of connection to the Namekians. For example, he could have a hidden Namekian power within him. As he explores this, he teams up with a group of Namekians to defend their planet from an outside threat like a powerful space pirate group.
There could be his friends or comrades in the hunt. For instance, someone like Annabeth who might be affected by his leaving and try to convince him to stay.
There could be an alien sidekick named Zorx. Zorx might be a small, furry creature with the ability to see in multiple spectrums, which helps Percy navigate through different planetary environments.
Annabeth could be a main character. She might be initially distrustful of Percy because of his mother but then come to see his true worth. Another could be Grover, Percy's loyal friend, who stands by him through all the difficulties. There could also be new characters, like a half - spider half - human hybrid who is Percy's distant relative and helps him understand his heritage.
One of the main characters could be the hotel manager. He or she is responsible for running the whole place, dealing with all kinds of problems, from unruly guests to staff issues. Another could be a young bellhop who has big dreams and is always getting into little adventures around the hotel.
Obviously, Percy would be one of the main characters. And then there could be the fan, who might be a young person, maybe a teenager named like, Sam or something. There could also be Percy's coach, who plays an important role in his training and success at the Olympics.
Obviously, Percy would be one of the main characters since it's about him remaining as praetor. Annabeth could also be a major character as she is Percy's close friend and love interest. Their relationship might be affected by Percy's role as praetor.
Annabeth could be a main character. She might be skeptical at first about Percy's new ability to control Styx, but then she uses her wisdom to help him understand the implications and possible uses of it. For example, she could research ancient texts to find out if there are any hidden dangers or benefits to Percy's control.
There could be his best friend Grover. Grover might try to find Percy after he runs away, adding an element of search and rescue to the story.
Obviously, Percy would be one of the main characters. Annabeth might also be there, as she is Percy's close friend and often involved in his adventures.