A new character could be a transfer student from another demigod camp. This student has a different set of powers and a unique backstory related to a less - known Greek god. They could initially clash with Percy but then become great friends as they face challenges together.
There could be a new teacher who is a half - centaur. They are there to teach combat skills in a more disguised way as part of a new after - school club. The teacher would have a strict but fair attitude and would help Percy and his friends improve their fighting abilities for future battles in the mythological realm.
There could be a demigod who is the child of a minor god that we haven't seen much in the original series. For example, the child of Hebe, the goddess of youth. This character could bring a fresh perspective with their powers related to rejuvenation and vitality.
The main characters would surely include Percy. Then, there could be Tyson, Percy's half - brother. Tyson could be really worried about Percy and use his strength to protect him while he's sick. Also, Chiron in his disguised form as a teacher at the school could play a major role. He has a lot of knowledge about demigod illnesses and could guide Percy's friends on how to help him.
There could be a new demigod who transfers to Percy's college. This demigod could have powers related to nature, like being able to make plants grow instantly. They would become Percy's ally in dealing with the campus - based mythological threats. Another new character could be a strict dean who is always on Percy's case, not realizing that Percy is actually protecting the college from real danger. And there might also be a mysterious janitor who actually has a deep connection to the underworld and gives Percy cryptic warnings from time to time.
There could be a new camper who has some really unique powers. Maybe a child of a minor god that we haven't heard much about in the original series. This new character could be both a friend and a rival to Percy.
Silena Beauregard is also underrated. She could be the focus in a fanfiction set in the school. Since she was a daughter of Aphrodite, she could use her charm and beauty skills in a different context at school. For example, she could use her powers to boost the confidence of shy students or mediate between feuding groups by using her charm to calm everyone down.
A new demigod from a previously unheard - of god or goddess. Maybe a child of a minor deity who has some unique powers that could either help or hinder Percy in the situation of the collapse. For example, a child of Hypnos who can manipulate sleep and dreams, and their powers could be used to either give Percy visions of how to fix things or put him in a dangerous trance.
A new character could be a half - angel, half - mortal who becomes Percy's ally or rival. They have powers related to both the Christian concept of angels and the Greek demigod powers. Another could be a seer from an ancient, long - forgotten civilization who has knowledge about Percy's true potential as a son of god.
She could be the daughter of a minor god that hasn't been introduced much in the original Percy Jackson series. For instance, the daughter of Hecate. This would give her powers related to magic, which would be really cool in the context of the story. She could use her magic to help Percy and his friends in battles or to solve some of the mysteries they encounter.
The spirits of the maze itself could turn against Percy. They could be angry at all the demigods who have been trespassing for years and decide to stop Percy from getting through by any means necessary.
One interesting character could be a demigod who is also a secret rockstar. For example, a son of Apollo might use his musical talents in a rockstar way. Another could be a siren who has left the sea to become a rockstar, using her enchanting voice to draw in crowds. And of course, Percy Jackson himself could make an appearance, maybe getting involved with the rockstar scene somehow.