There might be some magical creatures in the school that Percy gets to interact with. Maybe centaurs who are teachers at the school or satyrs that are his classmates. These interactions would be really interesting as they could introduce Percy to new ways of thinking and different cultures within the world of the fanfic.
Percy might also meet some humans who have a special connection to the world of the gods. They could be seers or descendants of ancient heroes. These humans could have their own skills and knowledge that they share with Percy, and together they could face the challenges that the special school presents.
He might meet other inter - galactic beings. For example, some sort of space - faring demigods from a far - off galaxy. Or he could encounter powerful entities that are the rulers of other planets.
Percy might meet an old enemy who has somehow been resurrected or changed in the future. This enemy could be more powerful and have a new plan to take over the world or destroy the demigods. Or he could meet a group of time - traveling demigods from an even further future who are trying to fix something in Percy's future that has gone wrong.
Percy might run into Loki. Loki is known for his trickery. He could either befriend Percy for his own devious plans or try to deceive him. Percy, being used to dealing with tricky situations in his own world, would have to be on his guard against Loki's schemes.
Percy could meet the school bullies. And they might pick on him at first, but then be in for a big surprise when he shows his strength. Also, he might encounter some teachers who suspect there's something different about him. Maybe a science teacher who notices his quick reflexes during an experiment or a history teacher who is amazed by his knowledge of ancient mythology.
He might meet other demigods who are not affiliated with the camp. These could be demigods who have been living on their own, trying to hide from the monsters and the chaos of the demigod world. They could have different views on how to use their powers and might teach Percy new ways to fight or survive.
He might meet his former classmates who have changed a lot since he left. Maybe some new students who are intrigued by his reputation.
In his new life, Percy could meet a kind - hearted librarian. She would be the one to introduce Percy to a whole new world of books that he never had time to explore before. There's also a chance that he'll meet a street - smart kid who helps Percy navigate the more mundane aspects of his new life, like finding the best places to eat or how to fix his bike. And perhaps a new teacher who has a mysterious past and seems to have an inkling of Percy's true nature.
He might meet a new teacher who is secretly a minor god or goddess in disguise.
In this fanfiction, Percy and Thalia could meet a powerful sorcerer who has been exiled from the magical community. The sorcerer could see potential in them and offer to teach them some ancient magic spells that could be useful against their enemies. Additionally, they may come across a group of forest spirits. These spirits could be initially hostile but after learning of Percy and Thalia's noble intentions, they could provide them with shelter and information about hidden paths that lead to safe places away from the threats they are running from.
He could meet other demigods from different regions. For example, a demigod from Scandinavia with powers related to ice.