Who could be the main antagonists in a 'Percy son of Tartarus fanfiction'?

The Titans that were banished to Tartarus could be major antagonists. They might see Percy as an intruder and a threat, and try to stop him from escaping or even try to use him for their own purposes. Also, the various monstrous creatures native to Tartarus, like the Empousai or the Arai, could constantly be attacking Percy.

The monsters native to Tartarus could also be antagonists. These could be huge, grotesque creatures that have never seen the outside world. They might attack Percy on sight, seeing him as prey. Some of them could be powerful enough to even give Percy a hard time, especially if his powers are weakened in Tartarus.

The Titans or Giants that were banished to Tartarus could be the main antagonists. They might see Percy as a threat or an opportunity to escape and seek revenge on the Olympians.

Maybe it's the Titans who are still lurking in Tartarus and don't want Percy and Zoe to succeed in whatever mission they have. The Titans could see them as a threat to their potential future plans of rising again.

Perhaps there's a new villain, a powerful sorcerer who has a vendetta against Percy. The sorcerer discovers that Percy is now at high school and decides to target the school. He uses his magic to create illusions and manipulate the minds of the students and faculty, turning them against Percy. The sorcerer might also be after the secrets Percy learned in Tartarus, thinking it can give him more power.

Some of the more powerful and vengeful spirits in Tartarus could be the main antagonists. These spirits could possess demigods or mortals close to Percy to get to him. They might be angry that he escaped their domain and want to drag him back. Additionally, there could be a group of rogue demigods who believe that Percy has been corrupted by Tartarus and they see it as their duty to stop him, even if it means becoming his enemies.

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.

It's also possible that there could be a new, unknown force in Tartarus that has been awakened by Percy's presence. This new entity could be extremely powerful and oppose Percy at every turn. It might be some sort of ancient, primordial being that has its own motives for not wanting Percy to succeed in whatever his mission in Tartarus is.

The obvious antagonists could be the angels. Since Percy is Lucifer's son, they would see him as a threat and try to stop him from causing any chaos or fulfilling any of Lucifer's supposed plans.

The main antagonists could be the Titans. They are powerful enemies in the Percy Jackson universe already. Now that Percy has Superman - like powers, they might see him as an even greater threat to their plans of overthrowing the gods. So, they would do everything in their power to stop him.