In addition to Annabeth and his family, he might interact with other demigods he knew before. They could be in awe of his new godlike state. There could also be some characters from the godly realm who are interested in Percy's return. They might want to use his power for their own purposes or they could be there to guide him on how to fully control his newfound abilities.
He could interact with his old friends at Goode, like Rachel. She has a special connection to the demigod world, and their relationship could be further explored. Also, there might be new teachers or students that Percy meets. Maybe a new student who is actually a demigod in hiding too, and they start to figure out each other's secrets.
There could be new characters as well, like a devil mentor figure who teaches Percy about his devil heritage. This character could be ancient and have a lot of knowledge about the devil realm. Or there could be an angelic character who is initially an enemy but later realizes Percy is not fully evil and they end up forming an unlikely alliance.
Well, perhaps Percy comes back with new and amazing powers. He might be like a hero who has seen many things during those years away. He could use his powers to save his old friends from a big danger that they can't handle on their own.
His old friends like Annabeth could be main characters. She might have been leading the group in Percy's absence and now has to adjust to his return. Grover could also be there, still being Percy's loyal friend and perhaps having some new knowledge about the world of magic and nature.
In this fanfiction, apart from Percy, we could see his friends from Camp Half - Blood like Tyson. Also, some of the teachers at Goode who might have a more significant role this time. There could be new demigods that Percy meets at Goode. And don't forget the gods or goddesses who might interfere in Percy's life at Goode in some way, for example, Poseidon could give Percy some kind of sign or power boost when he is facing a difficult situation at school.
Naruto would be very friendly and eager to make friends, so he'd probably start by introducing himself to Percy and his friends in a very enthusiastic way. Percy might be a bit cautious at first, but as he sees Naruto's powers, he'd be intrigued. They'd start sharing stories about their respective worlds, like Naruto talking about his village and Percy about Camp Half - Blood.
Definitely Annabeth. She and Percy have a strong relationship, and Hera's possessiveness would surely disrupt that. Also, other demigods at Camp Half - Blood could interact with Percy. They might sense that something is off with Percy due to Hera's actions and try to help him or at least figure out what's going on. And of course, the gods themselves might interact with Percy. Some gods might side with Hera, while others might oppose her possessiveness over a demigod like Percy.
Probably other demigods would interact with Percy. Maybe some demigods who are in need of a more stable influence in their lives would seek out Percy. Also, characters like Grover might find Percy in Hestia's care and there would be a reunion. And the gods and goddesses who are associated with the concept of home or family in Greek mythology, like Demeter, could also have interactions with Percy.
Obviously Percy is the main character. There could also be other characters from the original series, like Annabeth. She might be worried about Percy's transformation and try to help him adjust. And maybe some of the gods would also be involved, either trying to control Percy or use his new powers for their own ends.
Obviously, Percy would be the main character. There could also be some characters from the original Percy - related universe who might make an appearance to help him adjust or just to check on him. And from the Forks side, characters like Bella or Edward (if it's in the Twilight - Forks setting) could potentially cross paths with Percy. Maybe they become friends or foes depending on how the story unfolds.