Percy could show up at Annabeth's high school during a big event like a pep rally. He sneaks in, disguised as a delivery person. When he finally reveals himself to Annabeth in the middle of the crowd, she's shocked but overjoyed. They hug and Percy tells her he couldn't stay away any longer.
Well, perhaps Annabeth decides to surprise Percy at his high school by disguising herself as a new student. She enrolls in the school for a day and joins Percy's class. When Percy sees her sitting there, he can't believe his eyes. She then reveals her true identity during lunch break and they have a sweet reunion, sharing stories about their latest demigod adventures.
Perhaps Percy pretends to be a new student transferred to Annabeth's high school. He acts all mysterious and then during a class project, he reveals his true identity. Annabeth would be shocked and excited at the same time. Or, Percy could come in during a school dance. He asks the DJ to play their special song and then he steps out onto the dance floor to surprise Annabeth.
Percy, the son of Poseidon, and Annabeth, the daughter of Athena. Percy is brave and impulsive at times, while Annabeth is more level - headed. Their different personalities add to the charm of the story where Percy surprises Annabeth at school. It's their relationship that drives the plot forward in this fanfiction.
Well, perhaps Percy shows up at Annabeth's school with a bouquet of her favorite flowers. He could have skipped his own classes to come see her. He might wait outside her classroom and when she comes out, she's completely shocked and overjoyed.
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.
Maybe Percy brings her a special gift from his adventures, like a unique seashell. Annabeth would be really happy and they might share a sweet moment in the schoolyard.
One possibility is that Percy is in the middle of a boring class at Goode High when Annabeth shows up. He might be so shocked and happy that he forgets all about the lesson. They could then sneak out to a quiet place in the schoolyard and catch up on all their adventures and how much they've missed each other.