Well, they might become closer friends. Since they already have a connection in the original stories, in the fanfiction, being in the same school could lead to more shared adventures during school hours, like solving mysteries in the school basement or facing a new mythical creature that has targeted their school.
One great 'Percy and Annabeth at School' fanfiction is 'School Days in Camp Half - Blood'. It shows their daily adventures in a school - like setting within the camp. They face challenges like new monster threats during classes and exams, which is really exciting.
She might focus on her studies more. Since Annabeth is really into knowledge, she could pour all her energy into her schoolwork, like spending extra hours in the library or on research projects.
They could be involved in a high school project that turns out to be related to an ancient prophecy. Percy might use his water - controlling abilities in a science experiment in a really cool and unexpected way, and Annabeth would be there to explain the historical context behind it all.
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.
One idea could be that Percy and Annabeth are new students at a high school filled with mythological secrets. They have to hide their demigod status while also dealing with normal high school problems like exams and bullies. Maybe they join the school's swim team and debate club respectively, which could lead to some interesting interactions.
It's possible that Annabeth surprises Percy at high school by setting up a whole new section in the school library dedicated to Greek mythology. Percy loves Greek mythology, and when he discovers it, he's thrilled. Annabeth reveals that she worked with the school librarian for weeks to make it happen. This not only surprises Percy but also enriches the knowledge of the whole school about their demigod heritage.
Percy might become friends with the misfits or outcasts at school. His kind heart and sense of justice would draw him to those who are bullied. Annabeth, on the other hand, could be respected by the smart kids for her intelligence. She might form study groups and in the process, make new friends. But some students might be jealous of their closeness and the special bond they share.
There's Tyson, Percy's cyclops half - brother. In high school fanfiction, he can be really endearing as the big, strong but gentle guy. He might be on the school football team or something similar. And then there's Rachel Elizabeth Dare. She could be the artsy girl in school who has a bit of a crush on Percy and causes some jealousy with Annabeth, adding some romantic tension to the story.
She'd fit in by being herself. Her intelligence would make her a great addition to the academic scene. She could participate in debates and win them easily.