One interesting plot idea could be Percy leading the Chaos Army against an ancient, powerful enemy that has emerged from the darkest depths of Tartarus. The army could consist of various mythical creatures from different pantheons, united under Percy's leadership. Another idea is Percy having to deal with internal power struggles within the Chaos Army, where different factions have different ideas about how to wage war.
The Titans could be great antagonists. Even though they were defeated once, they could be making a comeback with new strategies and powers, seeing the Chaos Army as a threat to their plans of regaining dominance. Another option could be the Giants, who are also powerful and have a long - standing grudge against the demigods.
One idea could be Percy using his skills in a chaotic new world filled with strange mythical creatures that no one has ever seen before. He has to navigate through this chaos and find a way to bring order to this new part of the mythical realm.
One idea could be that Percy discovers a hidden connection to Chaos while on a quest. Maybe he stumbles upon an ancient artifact that has the power of Chaos within it, and it starts to change him in unexpected ways. For example, he might gain new powers that are related to the primordial chaos, like the ability to manipulate energy in a more chaotic and unpredictable form.
One idea could be Percy discovers new powers as the Host of Chaos and has to learn to control them while facing an ancient enemy that was sealed away long ago. He could struggle with the chaotic nature of his new abilities and how they affect his relationships with his friends at Camp Half - Blood.
One idea could be Percy facing a new type of monster that is immune to water. This would really challenge his typical combat style. Another could be Percy having to team up with an old enemy to defeat a greater threat that endangers both the mortal and demigod worlds. Maybe he has to journey to a completely unknown realm within the Chaos to retrieve a powerful artifact that is the key to saving his friends.
One idea could be Percy discovering his new role as the Father of Chaos gradually. Maybe he starts having strange dreams or powers that he can't explain at first. For example, he might accidentally create small chaos portals without realizing it. Another plot could involve Percy having to deal with the other gods' reactions. Some would be fearful, while others might see it as an opportunity to gain power through him.
One idea could be Percy losing the Blades of Chaos and having to go on a quest to retrieve them from a powerful new enemy. Maybe a dark sorcerer has stolen them to use in a ritual that would bring chaos to the mortal and demigod worlds.
One idea could be that Percy has to team up with Lady Chaos to stop a new threat that is emerging from the Underworld. This new threat is causing chaos (ironically) among the gods and demigods alike. They have to journey through different realms, facing various monsters and challenges along the way.
One idea could be Percy having to learn new powers that are unique to being the son of Chaos. For example, the ability to manipulate time in small ways or create portals to different realms that are only accessible to him. Another plot could involve Percy facing off against the traditional Greek gods who are threatened by his new status and powers.
One plot idea could be Percy Jackson getting lost in the realm of Chaos and being found by Artemis. They then have to work together to find a way back to the normal world while facing strange creatures unique to Chaos. Another could be a story where Artemis is sent on a mission by Chaos and Percy joins her, and during the journey they discover a long - lost prophecy that involves both of them. Maybe a plot where Percy has a vision from Chaos about a threat to Artemis and he has to protect her while also dealing with his own internal struggles.