Who could be the main antagonists in 'Percy Jackson adopted son of Kronos fanfiction'?

The Titans could still be antagonists. Even though Percy is now associated with Artemis, the Titans might see him as a threat or a tool to use against the gods. Kronos, for example, could try to turn Percy to his side by offering him power or by threatening those he cares about in Artemis's group.

Another god could be the antagonist. For instance, Hades might be jealous of Demeter's newfound 'son' and the attention Percy is getting. He could send his minions to cause trouble for Percy or try to undermine Demeter's influence on Percy, leading to a series of battles and challenges for Percy to overcome.

The Titans could be antagonists. Since Nyx is an ancient and powerful goddess, the Titans might see Percy as a threat because of his connection to her. They could try to either turn him against Nyx or simply eliminate him.

The Titans who were once associated with Pontus might be antagonists. They could see Percy as a threat to their plans if he is related to Pontus. They might try to stop him from fulfilling any tasks given to him by Pontus or try to use his new identity against him.

Hera could be a main antagonist. Since she's often jealous and protective of Zeus, she might not be happy with Percy being adopted. She could try to undermine him at every turn. Another could be Ares. He might see Percy as a threat, especially if Percy starts to gain more power as Zeus' adopted son.

Some of the traditional sea monsters like the Kraken could be antagonists. Since Percy is now in a more prominent position in the sea world as Amphitrite's adopted son, the Kraken might see him as a threat and try to attack him.

Another possibility could be a group of rogue demigods who are against any form of association with the underworld. They view Percy's new identity as something dark and evil. They form a group to oppose Percy and try to drive him out of the demigod community. They might even try to frame him for crimes he didn't commit in order to get the other demigods to turn against him.

Another possible antagonist could be some of the more power - hungry and jealous demigods. They might not like that Percy has been adopted by Apollo and is getting special attention. They could try to sabotage his missions or spread rumors about him to turn the other demigods against him.

There could also be a group of rogue demigods as antagonists. They might be jealous of Percy's adoption by Hermes and the powers that come with it. They could form a sort of anti - Percy alliance and try to sabotage his quests and make his life difficult among the demigod community.

One possibility could be the old enemies of Hydros. They might see Percy as a threat just because he is Hydros' adopted son. For example, some ancient sea monsters that Hydros defeated long ago could come back to seek revenge on his new family.