A group of rogue demigods could also be antagonists. These demigods might be jealous of Percy's status and Bianca's unique abilities. They could form a sort of anti - hero group that tries to undermine Percy and Bianca's quests and cause trouble for them. For example, they might steal important items that Percy and Bianca need for their mission.
The gods could potentially be antagonists. If the pregnancy goes against some divine law or prophecy, they might try to interfere. For instance, Zeus could see it as a threat to the order of things and send his minions to cause trouble for Percy and Bianca.
It could be the entities that thrive on the disorder in the chaos. They might see Percy and Bianca as threats to their way of life and try to stop them from achieving whatever goal they have in the chaos.
Maybe some of the more vengeful gods could be antagonists. For example, if Hera doesn't like Percy's decision to adopt Thalia, she could send various challenges their way. Also, there could be some ancient monsters that are awakened by Thalia's presence, and they would want to destroy her. These monsters could be sent by some minor gods who are jealous of the attention Thalia might get from the major gods.
Another possible antagonist could be some of the more bloodthirsty and power - hungry warlords or demons in the God of War universe. They might not care about Percy's origin or his powers, but simply see him as someone to be defeated or enslaved. These types of characters are often driven by pure greed and a desire for chaos, which would put them directly in Percy's path.
Maybe some of the more malevolent Greek gods could be antagonists. If Naruto's presence disrupts the balance of power among the gods, some of the jealous or power - hungry ones could try to get rid of him. For example, Hades might see Naruto as a threat to his domain and try to stop him from interfering in the affairs of the underworld.
Well, there could be some ice - related monsters or creatures that serve Khione. For example, ice giants or frost - breathing serpents. These could be constantly attacking Percy or trying to prevent him from achieving his goals while he's Khione's champion. Also, there might be some jealous demigods who think Percy is getting special treatment from Khione and they become antagonists by trying to sabotage him.
In Percy Jackson father fanfiction, the sea god Triton could be an antagonist. He might be jealous of Percy getting so much attention from Poseidon. The primordial sea gods or goddesses could also be antagonists. They might see Poseidon's relationship with a half - blood as a perversion of the natural order. And then there are always the minor gods who might feel that Percy and Poseidon are getting too much power and try to undermine them.
The Giants might also be antagonists. They could band together and target Percy's kingdom, believing that by destroying him and his rule, they can undermine the power of the gods further. They might use their brute strength and strategic thinking to attack Percy from different fronts.
Another option could be a group of rogue demigods who have turned to the dark side. They follow Percy to Forks, hoping to find some powerful artifacts there. They don't care about the vampires or werewolves and are willing to cause destruction to get what they want. Percy has to stop them while also dealing with the local supernatural creatures.
One potential antagonist could be a jealous player within the game. This player might see Kate as a threat to their own status or progress in the game and try to sabotage her at every turn. Another could be a rogue AI or a corrupted code within the game system itself that has developed a self - aware malevolence. It could target Kate specifically because she has some unique ability or item in the game. A third potential antagonist could be a character from the Percy Jackson mythos who has somehow entered the game world and wants to use it for their own dark purposes, seeing Kate as an obstacle to their plans.