Percy might surprise Nico by organizing a secret treasure hunt around the school. He could leave clues related to their shared memories and experiences. Each clue would lead Nico closer to a final 'prize' which could be a new sword that Percy had crafted especially for Nico. Also, Percy could ask the school cafeteria to serve Nico's favorite Italian food one day. He could then lead Nico to a special table decorated with candles and pictures from their past adventures, making it a very personal and unexpected surprise.
Well, Percy could stage a fake 'emergency' at school. He could get some of his friends to act like there's a monster attack (in a very safe and controlled way of course). When Nico comes running to help, he finds out it's all a ruse and Percy is there with a big smile and a new set of black clothes for Nico, knowing how much he loves his dark style. Or Percy could create a 'shadow show' in an empty classroom after school. Using his powers and some help from a light projector, he could project images of their adventures together onto the walls, making it a really unique and touching surprise for Nico.
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.
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.
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.
In the fanfiction, Percy could be there to check on Nico. Since Nico has had a tough time, Percy might want to make sure he's doing okay at school. He could offer to help Nico with any problems he's having, like dealing with bullies or difficult classes.
The camp leaders might betray them. If there is a power struggle within the camp, and Percy and Nico are seen as threats to the current leadership's power, the leaders could set them up. They could make it look like Percy and Nico are breaking camp rules or endangering the other campers, which would lead to the rest of the camp turning against them.
One way could be for Percy to find a group of true friends who can support him. They can stand up to the bullies together. For example, if there are some nice classmates, Percy can join them during breaks and lunches, and the bullies might be less likely to target him when he's in a group.
In this fanfiction, perhaps Percy and Nico will have an interesting conversation on their way home. Percy might share some of his latest adventures at Camp Half - Blood, while Nico could talk about his day at school.
Perhaps an old enemy from Greek mythology who has found a way to infiltrate the school in a modern form. This could be a minor god or a powerful monster. They want to get revenge on Percy and Nico for past defeats. They might be using the school's resources, like the science labs or the library, to create chaos or find a way to regain their full power.
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.
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.