In most cases, it might not be considered entirely appropriate within the school setting in fanfiction. Schools usually have rules about public displays of affection, and it can also be seen as a distraction to other students. However, in the context of fanfiction, which often bends the rules of the original world, it can be a way to show the intensity of their relationship.
Grover would be a great addition. He could be the quirky sidekick in the high school setting, always getting into comical situations while also providing some sage advice to Annabeth and Percy based on his own experiences. For example, he could help Percy figure out how to ask Annabeth to the prom.
Grover could be a great addition. He could be the goofy but loyal friend who always gets caught in the middle of Percy and Annabeth's drama. For example, he might accidentally spill some secrets that cause more trouble between them. Another good character could be Clarisse. She could be the school bully who has a grudging respect for Percy and Annabeth but still tries to cause problems for them now and then.
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.
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.
Often in these fanfictions, the pregnancy is used to add drama. It might lead to conflicts between Percy and Annabeth, like differences in their opinions on how to handle the situation. For example, Percy might be more laid - back while Annabeth wants a more structured plan. It also might show their friends rallying around them or being shocked. And sometimes, it's a chance to see how they adapt to changes in their social status at school due to the pregnancy.
Often, it could be a jealous classmate. Maybe someone who has a crush on Percy and sees Annabeth as a threat, so they try to create problems between them. Another could be a strict teacher who doesn't like Percy's carefree attitude and Annabeth's independent thinking, always trying to give them a hard time.
Friendship is a very common theme. In middle school, Percy and Annabeth are starting to build a bond. Their different personalities - Percy's more laid - back and Annabeth's more studious - make for an interesting dynamic as friends.
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.
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.