One possibility is that the Greek class is a place for Percy and Annabeth to show their relationship development. They could be paired up for a project on a particular Greek hero. While working together, they start to understand each other better. Annabeth might be really into the research part, while Percy brings in his practical understanding of how the hero's traits could be applied in a real - life - or rather, demigod - life - situation. And through this, their bond deepens as they both contribute their unique perspectives.
It could be Chiron in disguise. Since he has a vast knowledge of Greek mythology, he would be a great teacher. He could also use his centaur form in some secret or magical way during the class to teach important lessons that only Percy and Annabeth would notice.
Another option for the main antagonist could be a spirit of an ancient Greek scholar who was banished from the world of the gods. This spirit haunts the Greek class and tries to possess Percy because he sees Percy as a way to get revenge on the gods. It causes chaos in the class, making it difficult for Percy to focus on his studies and also putting his friends at risk.
One fanfiction has Percy being the only one who can see the Greek gods during Greek class. They interact with him in ways that his classmates can't perceive. This creates a lot of humorous and also some tense situations as Percy tries to keep his cool while the gods mess around in the classroom. The unique plot makes it stand out among other fanfictions in this genre.
A really interesting 'Percy in Greek Class' fanfiction could involve Percy accidentally revealing some of his godly connections during a Greek class project. The story then unfolds as his classmates react in different ways, some in awe and some in disbelief. It's a great way to explore how Percy's world would interact with the more academic study of Greek mythology.
Perhaps Percy could have a dream during Greek class about an upcoming prophecy related to the class. In the dream, he sees that a certain ancient Greek artifact hidden in the school is going to be discovered, and it will either bring great danger or great power. So, he spends the rest of the class trying to figure out how to stop or find it first. Also, he could get into an argument with a teacher who doesn't believe in the real existence of the Greek gods, but Percy has to prove it without revealing his true identity as a demigod.
His water - controlling powers could cause some interesting situations. For example, if there was a leaky faucet in the classroom, he could accidentally make the water spray everywhere in a fit of distraction. Or he could use it to create a cool mist during a hot day to cool down the classroom, much to the surprise of his classmates.
Well, he might get some strange looks from his classmates. Some might think he's just showing off or being weird. But if there are any other demigods in the class, they could be secretly impressed or even a bit envious that he's so casually using Greek.
Perhaps Percy would use his knowledge of Greek gods and goddesses to impress the teacher. He could share some unique insights about a particular deity that are not commonly known. This could lead to him getting special privileges in the class, like being excused from a difficult assignment or getting extra credit.
One way could be to describe the shock on his classmates' faces. For example, 'Percy blurted out a Greek phrase in the middle of class, and everyone's jaws dropped.'