Definitely Annabeth. In a high school setting, she could be the super - smart girl who helps Fem Percy with her studies while also being involved in the demigod stuff. Her strategic mind would be great for solving high school mysteries too.
Grover would be an interesting addition. He could be the shy, but loyal friend who always has Fem Percy's back. Maybe he's part of the school's environmental club and uses his nature - loving side to make the school a better place.
Grover could be a great addition. He could be the goofy but loyal friend who always gets caught in the middle of Percy and Annabeth's drama. For example, he might accidentally spill some secrets that cause more trouble between them. Another good character could be Clarisse. She could be the school bully who has a grudging respect for Percy and Annabeth but still tries to cause problems for them now and then.
Grover would be a great addition. He could be the quirky sidekick in the high school setting, always getting into comical situations while also providing some sage advice to Annabeth and Percy based on his own experiences. For example, he could help Percy figure out how to ask Annabeth to the prom.
One popular storyline could be Fem Percy dealing with the typical high school drama while also having to hide her demigod powers. For example, she might struggle to keep her identity a secret when she accidentally uses her powers during a school sports event.
Definitely Pikachu. Pikachu is Ash's loyal partner and can add a lot of cute and funny moments in the high school setting. Another interesting character could be Misty. She could be the tough girl who has her own ideas about Pokémon training and often clashes with Ash in a friendly way. Gary Oak is also great. His rivalry with Ash can be taken to a new level in high school, competing not just in Pokémon battles but also in academics or popularity.
I think Tiana from 'The Princess and the Frog' would be a great character. She could be the hard - working student who is always trying to save up for college by working part - time jobs at the school cafeteria or library. She might also be part of a cooking club and compete in school - wide cooking contests. Another interesting character would be Hercules. He could be the star athlete in high school, but also a bit of a dork when it comes to academics. He would constantly be trying to balance his sports achievements with his need to study and fit in with the smart kids. And Maleficent could be the mysterious, feared teacher who has her own hidden agenda for the school.
Lizzie could be a popular cheerleader - type character. She's always trying to get Ciel's attention and is really good at sports. But she also has a bit of a temper when it comes to other girls getting too close to Ciel. And then there could be a new character, a shy transfer student who gets caught up in the drama between Ciel and the other students, and she has her own special abilities that she's not aware of at first.
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.
One interesting storyline could be Fem Luffy joining the high school's sports team. Since Luffy is known for his physical strength and determination in the original story, as a female in high school, she could be the star athlete. Maybe she overcomes gender biases in sports at school. For example, some might think that certain sports are not for girls, but she proves them wrong with her skills and tenacity.
One of the most interesting characters to include would be Hermione from Harry Potter. Her intelligence and knowledge of magic could help Percy and his friends in many situations. Also, Captain America from the Avengers. His leadership and sense of justice would blend well with Percy's own heroic nature. And Clary from the Mortal Instruments, her skills as a shadowhunter and Percy's demigod abilities could create a really engaging story.
Obviously, Percy and Artemis are the main characters. Percy, a demigod with Poseidon's powers, often brings his adventurous and sometimes reckless nature into the high school setting. Artemis, the goddess of the hunt, is strong - willed and independent. Their interactions are what drive most of these fanfiction stories.