Besides Percy, his agent could be a character. The agent would be responsible for handling Percy's endorsements, scheduling his competitions, and dealing with the business side of his athletic career. There could also be a physiotherapist, especially if Percy gets injured during his training or competition. This person would help him recover and get back to peak performance. Another possible character is a fan. A die - hard fan of Percy who follows his every move, collects his memorabilia, and is always there to cheer him on, either at the stadium or through social media. And there could be a local sponsor who is investing in Percy and hoping for his success at the Olympics.
The bullies themselves would be key characters. They could be the typical mean kids in Percy's school or wherever the story is set.
Well, there could be new characters created specifically for this fanfiction. For instance, Chaos might have his own loyal servants or minions who interact with Percy. There could also be other heroes or demigods from different pantheons. They might come to Percy for help or to challenge him. And of course, Percy's mother, Sally. She might be worried about her son and try to reach out to him, even though he is now in the realm of Chaos. Her presence could add an emotional aspect to the story as Percy has to balance his new life with his love for his mother.
Grover could also be a major character. As Percy's best friend, he would probably be involved in trying to stop Percy if he thinks Percy has gone too far. Or, if he sees the corruption in Olympus, he may side with Percy. Grover's connection to nature means he could play an important role in the events that unfold, like using nature spirits to either protect Olympus or aid Percy depending on his stance.
The Hunters of Artemis are very likely to show up. They are Artemis's loyal followers and would surely be involved in the search for their mistress. Annabeth could also be there. She's Percy's friend and has great wisdom, which could be useful in devising a plan to save Artemis. Grover might be another character. His ability to sense things could help in tracking Artemis or finding clues about her whereabouts.
One common theme could be the athlete's journey to the Olympics. It might include their training, the sacrifices they make, and the challenges they face along the way. Another theme could be friendship or rivalry among the athletes. For example, Percy might have a friendly competition with another athlete which helps them both grow. Also, the theme of perseverance in the face of injury or setbacks can be prevalent. An injured Percy might have to fight through pain and self - doubt to get back in the game and compete at the Olympics.
I'm not sure specifically since I don't know the exact fanfiction, but it could be his friends who might be either involved in his hacking activities or completely unaware of them. Maybe there's a mentor - like figure who guides him in the world of hacking.
There could be a rival within the family. Someone who wants Percy out of the way, perhaps for inheritance reasons or because they're jealous of Percy's abilities or popularity. This rival could be the one who instigates the events that lead to Percy's disownment. And then there might be a mentor - like figure outside of the family who takes Percy in after he's disowned and helps him to grow and face his new situation.
Annabeth is often a popular character. She could be in a story where she has to help Percy deal with his relationship with Poseidon. Maybe she gives him advice on how to handle Poseidon's overbearing nature or how to make the best use of the gifts Poseidon gives him.
Grover could also be a main character. He might be at the scene when Percy gets drunk and try to use his nature - related powers to sober Percy up. Grover could also provide some comical relief with his reactions to Percy's drunken state, like his horrified expressions or his attempts to herd Percy like he would a wild animal.
Often in these types of fanfictions, aside from Percy, there might be minor characters that serve as catalysts for his actions. It could be a random villager who Percy saves, which then sets off a chain of events. Or perhaps an old mentor figure who appears briefly to give Percy some advice that helps him in his one - man battles.