Well, obviously Percy Jackson and Jason are the main ones. Given that it's a bashing fanfic, they will be at the center of the story. Their actions, personalities, and relationships will be the focus.
Other characters from the Percy Jackson universe are also likely to be involved. Friends of Percy like Annabeth might be there to support Percy and show how he is better than Jason. Or characters associated with Jason could be present to either defend him (if the bashing is not one - sided) or to be used as examples of why he's not as great as Percy.
Another theme could be character flaws. It may explore the flaws of Jason more deeply than in the original works. Maybe it shows how his actions in certain situations, like his decision - making during battles, are not as good as Percy's. This can be used to create drama and conflict within the fanfic.
Obviously, Percy Jackson himself would be the main character. The tigers that raise him would also be important characters. They could be like his family in the story.
From the Tsukune side, Tsukune would be there as the character being bashed. His friends from his own story might also make an appearance, but mainly to be overshadowed by the Naruto characters. For example, Moka could be in it, but the focus would be on how Naruto characters are better in various aspects compared to her and Tsukune.
Naruto himself could be a main character as the fanfic might explore how his life could have been different without the Sandaime's influence. Another likely main character could be Orochimaru, especially if the fanfic focuses on the Sandaime's failure to deal with him properly.
Percy Jackson himself would obviously be a main character since it's a 'Reborn Percy Jackson Fanfiction'. His friends like Annabeth Chase are also likely to be main characters. She could play a crucial role in helping Percy adjust to his new life after being reborn. Grover would probably be there too, still being Percy's loyal friend. And the gods, especially those who have a connection to Percy like Poseidon, would also be important characters as they might have different reactions to Percy's rebirth.
Some of the likely characters could be the regular mortal kids at Percy's school. They might not understand his differences and bully him because of his ADHD and dyslexia. Another possibility is some jealous demigods who envy Percy's popularity or his special abilities.
Percy Jackson himself is almost certain to be a main character. After all, the fanfiction is centered around him after the war. Annabeth Chase would also likely be a main character, as she is Percy's love interest and a powerful demigod in her own right. Grover, Percy's best friend, would probably be there too, still looking out for nature and helping Percy in his new adventures.
Percy Jackson himself would be the main character, obviously. Since he is the God of Matter in this fanfiction. His friends like Annabeth Chase would also likely be important characters. She could be there to support Percy and use her own intelligence to help him understand and control his new powers.
Obviously, Percy Jackson himself would be a main character. Since it's about him being in a god camp. Annabeth Chase is also likely to be a main character as she has always been an important part of Percy's life. Grover, Percy's best friend, would probably be there too. And there might be some new characters, like other god - like beings or powerful demigods in the camp that Percy interacts with.
In 'demigods revealed percy jackson fanfiction', Percy Jackson is bound to be a central figure. But other demigods like Nico di Angelo might also take on major roles. Since it's about demigods being revealed, characters who have secrets or hidden aspects to their identities, such as Thalia Grace, could be important. Also, the gods might play a more prominent role as they are related to the demigods, so Zeus or Poseidon could be significant characters in the story.