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.
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.
In this fanfiction, Voldemort or his remaining followers could be major antagonists. They wouldn't like the idea of Harry having new allies in Percy and the demigod community. From the Percy Jackson side, the Titans or some of the more malevolent gods might not be happy with the alliance either. They could try to break it up or cause trouble for the two boys, seeing them as a potential force against their own plans.
A powerful Titan who has escaped from Tartarus and wants to disrupt the Hunt could be an antagonist. They might see the Hunt as a threat to their plans for chaos. Another could be a rogue demigod who has turned against the Hunt and is now working for their own selfish gains, perhaps trying to steal the Hunt's magic weapons.
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.
Piper could also be a potential love interest in this scenario. Given her charm - speaking abilities, she could either be a rival to Percy in the 'player' game or be someone he tries to charm. Their interactions would be filled with a mix of friendly banter and underlying romantic tension.
The Cyclops Tyson could be an ally. He has a strong bond with Percy and his strength could be a great asset. In a fanfiction where Percy is the God of Light, Tyson could be like a protector of Percy's light - based temples or strongholds. Also, the sea creatures that Percy has befriended over the years might come to his aid. Since Percy has his roots in the sea and now has light powers, they could work together in a unique way, like the sea creatures using their natural abilities to help spread Percy's light across the oceans to keep dark sea - based threats at bay.
The spirits of the maze itself could turn against Percy. They could be angry at all the demigods who have been trespassing for years and decide to stop Percy from getting through by any means necessary.
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.
Another option could be a group of rogue demigods. These demigods have turned against the Olympians and see Weaver as someone who could potentially foil their plans. They might have their own ideas about how the world of demigods should be run and are willing to do anything to achieve their goals, including getting rid of Weaver.
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.