In some more creative fanfictions, new characters might be introduced. For example, a powerful demigod who was born in Tartarus and has unique abilities. These new characters can add a fresh twist to the story, interacting with Percy and the others in unexpected ways, and often bringing new plotlines related to the mysteries of Tartarus.
Obviously, Percy Jackson himself is a main character. Annabeth might also be very involved, either helping him escape or being there to welcome him back. Grover could be another main character, perhaps using his nature - related powers to assist in some way.
There could also be some characters unique to the fanfiction. Maybe a new demigod who has some special power related to Tartarus and ends up joining Percy on his quest. Or perhaps an ancient being who was imprisoned in Tartarus long ago and has knowledge that Percy needs to complete his mission.
Obviously, Percy is the central character. But often, Annabeth can also play an important role, even if she's not physically in Tartarus with Percy in some stories. She might be trying to find a way to rescue him from the outside. Another common character is Nico, who has some knowledge of the Underworld and Tartarus and could potentially be a key figure in helping Percy either survive or escape.
He would surely interact with Annabeth. Their relationship is central in the Percy Jackson series, so in a Tartarus fanfic, she'd likely be there to support him or be in a similar situation as him.
Obviously, Percy Jackson himself is a main character. Since he is the God of Tartarus in this fanfiction concept. Annabeth Chase might also be a key character as she is Percy's long - time friend and love interest. Her reactions to Percy's new status and how she supports or challenges him can be a big part of the story.
Well, obviously Percy Jackson himself is often a main character. He's the hero of the original series, so in fanfiction related to Demeter, he usually plays a big role. Demeter is another main character, as the fanfiction is centered around her in some way. Sometimes her demigod children also make an appearance. For example, her daughter who might have some special powers related to plants or nature.
The main antagonist could be Nyx. She is a powerful primordial goddess of the night, and Tartarus is her domain in a way. She might see Percy as an intruder and try to stop him from escaping or achieving his goals there.
Percy himself is often very popular. He's the main character in the original series, so in fanfiction about Tartarus, his journey and how he overcomes the challenges there are always interesting. Annabeth is also a popular character. Fans love to write about her either trying to rescue Percy or being part of his adventure in Tartarus. Nico di Angelo is another one. His powers and his somewhat dark and mysterious nature make him a great addition to Tartarus - related fanfictions.
Percy is the main focus, as he has to navigate this new aspect of his identity as the son of Moros. But there could also be some antagonists that are main characters in their own right. For example, a demigod who is jealous of Percy's new - found status and power could be a main antagonist. Another character could be a minor god who is trying to use Percy for his own purposes. This god might seem friendly at first but then reveals his true motives. And let's not forget Percy's family. His mother, Sally Jackson, would still be an important character. She would be worried about her son and how this new development affects him. And Poseidon might also make an appearance, perhaps to have some sort of conversation or confrontation with Percy about his new parentage.
Perhaps the antagonist could be a corrupted demigod. Someone who was also in Tartarus, but instead of coming out stronger in spirit like Percy, they were twisted by the darkness there. They now want to bring that same darkness to the world of the demigods and see Percy as the main obstacle to their plans.