Well, Percy could bring some modern - day items with him that might amuse or baffle the inhabitants of Ogygia. He might introduce Calypso to things like a smartphone (if it works there) and show her pictures of his friends and family. This could create an interesting cultural exchange between Percy's world and the world of Ogygia.
He could also meet some minor nymphs or spirits that inhabit the island. These beings might be curious about Percy's return and have their own stories to tell. For instance, there could be a water nymph who has some knowledge about a prophecy related to Percy and his return to Ogygia. Or a spirit that has been observing the changes in Ogygia since Percy last left and can give him some insights on what has been going on in his absence.
In this fanfiction, Percy might struggle to catch up with the school work he missed. There could also be some sort of rivalry or conflict with a new student. And perhaps he'll discover a hidden part of the school that has some special significance related to his past adventures.
Perhaps Percy goes back to Goode to find a sense of normalcy. He might try to participate in school activities like sports or clubs. However, his past as a demigod will surely follow him. His powers could accidentally surface during a school event, causing chaos and confusion among his classmates. He'd then have to figure out how to cover it up while also protecting those around him from any potential danger.
He could potentially change some events in the past that had a big impact on his present life. Say, he could prevent some of the early attacks by monsters that made his life so difficult growing up. This would completely alter the course of his life and the lives of those around him. It's a really cool concept to think about how one small change in the past could have a huge ripple effect in the future.
In this fanfiction, Percy might encounter ancient Greek heroes like Hercules. He could join them in their quests and learn from their battle skills.
In the 'Percy goes back in time fanfic', he may also meet his younger self. This could lead to some really interesting and confusing situations. He would have to be careful not to disrupt the timeline too much while still achieving whatever his goal is for going back in time.
Well, she might cause quite a stir. Maybe she'll outshine everyone in academic competitions, which could make some students jealous. And she could also form a study group with Percy and their friends, sharing her vast knowledge of mythology and ancient civilizations.
When the Elden Ring Tarnished goes back to his fanfiction, he may be able to use the knowledge and skills he gained in the real Elden Ring world. This could give him an advantage in the fanfiction world, allowing him to overcome challenges more easily. He might also be able to introduce new elements from the real game into the fanfiction, changing it in unexpected ways.
In the fanfiction, when Annabeth goes to Percy's high school, she would probably form a study group. With her knowledge, she'd help Percy and his friends get better grades. Also, she might start some kind of architecture or history club in the school since she has a passion for those things.
Well, he might get into all sorts of trouble. Maybe he'll show off his demigod skills during a gym class and shock everyone. He could also meet some new friends or enemies who are part of Annabeth's school world. And perhaps he'll get involved in a mystery that's specific to the school, like a strange disappearance in the library that only he can solve with his unique abilities.