In this fanfiction, the plot might revolve around Percy's struggle as a slave of the gods. He could be used as a tool by the gods in their power games. For example, the gods might send him to retrieve powerful artifacts from dangerous places, and all the while he is trying to resist this unjust treatment and regain his freedom.
In this fanfiction, it could be that there is a prophecy that Percy is fated to either save or destroy the gods. Circumstances push him towards the latter. He might learn some dark secrets about the gods' origin that make him believe they are a threat to all existence. So he embarks on a journey filled with challenges and battles to take them down.
One possible plot could be that Percy has somehow angered the gods, perhaps by accidentally disrupting a major ceremony. As a result, they send various mythical creatures to hunt him down. He has to use his wits and demigod powers to outsmart them and find a way to make amends with the gods.
Perhaps the fanfiction could center around Percy discovering a hidden prophecy that is the key to ending the war between the gods. He then has to go on a dangerous quest to fulfill it. Along the way, he meets new allies and enemies, and has to use his wits and powers to overcome various obstacles. This could also lead to some character development for Percy as he faces difficult decisions and moral dilemmas.
One possible plot could be that Percy and his friends are faced with a new and extremely powerful threat that endangers not only the mortal world but also the entire pantheon. In order to defeat it, they are offered a chance to become gods. They have to go through a series of trials that test their loyalty, courage, and wisdom even more than before. Percy might struggle with the idea of leaving his mortal life and family behind, but realizes it's for the greater good. Along the way, they face old enemies who are jealous of their potential ascension and try to stop them at all costs.
Maybe Percy unknowingly breaks some ancient and very strict laws of the Gods. For example, he might interfere with some sacred rituals or places that are off - limits to mortals, even demigods like him. In the fanfiction world, the Gods could be very unforgiving when it comes to such violations and decide to kill him as a result.
Maybe Percy hides because he discovers a secret about the gods that they don't want him to know. For example, he might find out about some underhanded deal among the gods that could endanger the demigods. So, in order to protect himself and his friends, he decides to hide.
Well, Percy Jackson himself would obviously be the main character. And since it's about being a slave of the gods, gods like Zeus, Poseidon, and Athena could be important characters as well, as they might be the ones either enslaving him or having some role in his enslavement or liberation.
Well, there could be Percy going on quests with the gods by his side. Maybe they help him face new and more powerful monsters that he couldn't handle alone. For example, fighting a giant that has been awakened by an ancient curse.
One interesting plot twist could be that Percy discovers he has a hidden connection to the father of the gods that gives him new and unexpected powers. For example, he might find out he can control a part of the godly realm that was previously unknown. This would change his role in the demigod world and make him a target for both friends and foes who want to use or stop his newfound abilities.
One idea could be Percy being forced to do Kronos' bidding while secretly trying to find a way to break free. He might be sent on dangerous quests that are actually part of Kronos' plan to gain more power. Another could be Percy having to interact with other characters who are also under Kronos' control and trying to figure out who can be trusted. Maybe he discovers a hidden power within himself that could be the key to his liberation.