Who could be the main antagonist in a 'Percy Jackson Turns into a God' fanfic?

A powerful Titan who wants to use Percy's newfound power as the God of Pain for his own evil purposes could be the main antagonist. This Titan might see Percy as a tool to spread chaos and destruction, and he tries to manipulate Percy into using his pain - based powers to harm innocents. Percy would then have to resist this Titan's influence and fight against him.

Perhaps a forgotten or banished god could be the main antagonist. This god, filled with resentment for being cast out, could return with a vengeance and start causing chaos. He might be powerful enough that the only solution Percy sees is to slay him. This antagonist could bring in a lot of new lore and backstory to the fanfic as Percy uncovers the secrets of this god's past.

Perhaps it could be a new evil force created as a result of Percy's sudden god - born existence. His new - found power could have unbalanced some ancient magic or prophecy, and this new evil entity rises to oppose him and restore the old balance. It might be a being made of dark magic that has a vendetta against Percy for disrupting the natural order of things.

It could be an ancient and powerful Titan who was once in charge of fate but was overthrown. Now he wants to regain his power over fate and sees Percy as a threat. He might try to manipulate Percy into making bad decisions regarding fate.

Perhaps a powerful sorcerer who has somehow managed to gain control over some of the angelic powers and wants to use them to rule the world of demigods. He could be jealous of Percy's connection to the angel of God and see him as a threat to his plans. This sorcerer would use dark magic combined with the misused angelic powers to create all kinds of obstacles for Percy and his friends.

A powerful dark wizard or sorcerer from a different realm could be the main antagonist. The eclipse could have opened a portal to their realm, and they see the world of Percy Jackson as a new place to conquer. They would use their dark magic against Percy and his friends, and Percy, as the God of Eclipse, would have to use his unique powers to stop them.

It could be a new, dark demigod who has been corrupted by dark magic. This demigod might envy Percy's relationship with the gods and the God of Thunder in particular. He or she could be gathering an army of monsters and using dark powers to try and take over the world of the demigods and gods alike. They would be a formidable foe as they understand the ways of demigods but also have access to dark powers that are not easily countered.

A powerful Titan who was once in charge of storms and wants his power back. He sees Percy as a threat and tries to stop him at every turn.

It could be a jealous demigod. Maybe someone who has always been in Percy's shadow and decides to frame him for betraying the gods in order to get rid of him and gain more power and recognition among the demigod community.

It could be a new, powerful Titan that has emerged from the depths of Tartarus. This Titan might be seeking revenge on the demigods for imprisoning the other Titans and sees Hylla and Percy as the biggest threats.