There could also be other characters from the original Percy - related universe. For example, his friends like Annabeth might be present. They could play important roles in either trying to help Percy or having to deal with the consequences of his banishment. Mortals or other minor gods who interact with Percy in his new state could also be main characters as they contribute to the development of the story.
Obviously, Percy is one of the main characters since the title implies it. He would be the central figure whose story the fanfiction revolves around.
In addition, there might be new characters created specifically for this fanfiction. These could be beings who have some connection to the world of banished gods or those who are in a similar situation as Percy. They could bring new dynamics and conflicts to the story.
It could be Ares. He is often portrayed as a violent and unpredictable god. Percy might banish him if he goes too far in causing wars and chaos among mortals. His banishment would have a huge impact on the battlefields of the mortal world.
There could be other gods as well. For instance, Zeus might play a role, perhaps being suspicious of Percy's newfound godly powers or seeing him as a threat to his own authority. Hermes could also be there, acting as a messenger or a guide to Percy in the world of the gods.
Obviously, Percy Jackson is the central character. He is the one who is banished and has to deal with the consequences. His friends like Annabeth Chase might also play important roles. She could be trying to find a way to bring Percy back or dealing with the fallout of his banishment at Camp Half - Blood.
The main character is Percy. However, in the fanfiction, there could be a new character created specifically for the story, like a young apprentice of Percy who has a unique ability. There may be an old and wise god who has some secrets about Percy's past and is reluctant to share them at first. Also, there could be a group of demigods who are initially skeptical of Percy but then come to believe in him and join his cause as he tries to reclaim his position among the gods.
Obviously, Percy would be the main character. As he is the one born a god in this fanfiction.
The main antagonist might be a new character, a powerful being that rules the realm where Percy is banished. This being could see Percy as a threat to his or her power and try to stop Percy from finding a way back.
A powerful sorcerer who also wants to claim the island for his own could be the main antagonist. He sees Percy as an obstacle to his plans and tries to eliminate him. The sorcerer might have control over some of the dangerous creatures on the island and use them to attack Percy.
The main antagonist might be an ancient and powerful being that has awakened. This being could see Percy and Annabeth as a potential threat to its plans of taking over the demigod world. So, it uses its influence to have them banished, thinking that without them, it would be easier to conquer. For example, a long - forgotten Titan who has found a way to break free from its prison.
In the fanfiction, the environment of Tartarus itself could be considered an antagonist. The extreme heat, the toxic gases, and the ever - present danger of falling into bottomless pits. And on top of that, there could be some sort of demon - like creatures that are specifically created or summoned to hunt down Percy and Zoe and prevent them from achieving their goals.
One possible interesting plot could be Percy's struggle to adapt to his new status as a banished god. He might have to deal with the loss of his former powers and the isolation from his old world.