Percy might become friends with Fred and George. They are always up for some fun and mischief, and Percy could get drawn into their antics. Also, Ginny could be his friend. Since she's a strong - willed and friendly girl, she might take Percy under her wing and introduce him to the ins and outs of Hogwarts life.
He could be friends with Neville. Neville is kind - hearted and they might bond over their shared experiences of feeling a bit out of place at Hogwarts. Another friend could be Luna. She has an open - minded and unique personality, and she would likely accept Percy for who he is.
His friends could include Seamus. Seamus is a bit of a fiery character, and Percy could learn a lot from his passionate approach to magic. And then there's Cho. She's friendly and popular, and might befriend Percy and help him integrate into the Hogwarts social scene.
Well, perhaps Percy could be a new student at Hogwarts. He might face challenges like making friends in a new and magical environment. Maybe he gets sorted into a house and has to learn to fit in with his new housemates. He could also discover some hidden secrets about Hogwarts that are not known to many.
Some of the more traditional and rule - following demigod groups at Camp Half - Blood could be against him. They believe in following the established ways and Percy's rogue behavior goes against that. They might see him as a troublemaker and try to bring him back to the 'right' path.
There could be a school janitor who is actually an old demigod who retired from the hero business. He could give Percy some valuable advice based on his own experiences. And of course, Percy will surely meet Annabeth's classmates, some of whom could be friendly and some not so much, depending on how they react to the new boy in school.
There's a chance that Percy meets the personification of Tartarus itself. It could be a shadowy, all - powerful being that tries to break Percy's spirit. Percy, being the brave hero he is, would have to resist and find a way to either outwit or overpower this entity in order to continue his journey in Tartarus.
Perhaps Percy will meet a group of environmentalists. Given San Francisco's reputation for being environmentally conscious, they could be fighting against some sort of sea - related pollution that Percy gets involved in. He might use his powers and knowledge to assist them, and in the process, make some good friends.
He could meet some Aboriginal heroes or spirits. They might have their own powers and knowledge that Percy can learn from.
There could be a strict drill sergeant as one of the main characters. This person would be constantly pushing Percy to his limits and teaching him discipline. Another character might be a fellow student who becomes Percy's best friend. They could support each other through the tough times at military school.
She might initially be a bit of an enigma to them. But as time passes, she could become a great friend. For example, she could help Percy's friends with their homework, especially in subjects like math or history that she's excellent at.
At the same time, Percy could be determined to find out why they betrayed him. He wouldn't just accept it passively. He'd be on a mission to uncover the truth, whether it was some outside influence or a misunderstanding that led to their actions. And he might also be a bit vengeful, thinking about getting back at them in some way, though his good nature might prevent him from going too far.
A powerful sorcerer could be the main antagonist. He might be after Percy's powers or trying to use the school as a base to spread chaos. Maybe he wants to open a portal to the underworld right in the middle of the schoolyard.