Well, a cool plot could be that Percy, as the General of Kronos, discovers a hidden power within Kronos' forces that could either save or destroy the world. He then has to race against time to figure out how to control this power. Also, there could be a sub - plot where Percy is constantly in conflict with his old Percy Jackson values while leading this new role. Maybe he has to find a way to reconcile his past self with the General he has become.
A possible plot for the 'Percy Jackson General of Kronos' fanfiction is that Percy, in his new role, uncovers a conspiracy within Kronos' ranks. Some of the powerful members are planning to overthrow him and use the army for their own evil purposes. Percy has to use his wits and his unique skills to outmaneuver them. He might also form unexpected alliances within the army, like with some of the less - known or outcasted monsters, to strengthen his position and protect the army from being misused.
One idea could be Percy having to face moral dilemmas as he discovers more about his connection to Kronos. For example, he might be tempted by the power Kronos once held. Another could be Percy having to deal with the distrust of his friends who fear he'll turn into an heir of Kronos in a bad way. He could also go on a quest to find a way to sever his connection to Kronos if it's a negative one.
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.
One idea could be Percy having to face Kronos in a dream realm where Kronos tries to manipulate his mind. Maybe Kronos shows Percy a false future where his friends turn against him to make Percy doubt his alliances.
One idea could be that Fem Percy has a unique connection to Kronos. Maybe she can see into his past and uses that knowledge to try and prevent his rise. For example, she discovers a long - forgotten weakness of his from his early days. Another plot could involve Fem Percy being tricked by Kronos into doing his bidding at first, but then realizing his true evil nature and turning against him. This could lead to an intense battle of wills between them.
One plot idea could be that the female Percy Jackson has a psychic connection with Kronos' past self. She starts seeing visions of his rise and fall in the Titanomachy. Another could be that Kronos, in some way, tries to use the female Percy as a tool to regain his power but she manages to turn the tables and uses his own schemes against him. Maybe she discovers a long - lost secret about Kronos that could either save or destroy the world of the demigods.
Another plot could involve Percy being sent on a quest by the gods to find a way to sever his connection to Kronos completely. Along the way, he meets new allies and enemies, and has to face challenges that test his loyalty to both his new identity and his old friends.
One idea could be Percy struggling with the dark influence of Kronos while still trying to maintain his loyalty to his friends at Camp Half - Blood. Another could be Percy having to hide his true identity as Kronos' adopted son from his closest allies. Maybe he discovers some long - lost powers or knowledge that Kronos had hidden away for him, which he must use to either save or destroy the world of the gods.
One idea could be Percy having to choose between the powers of Kronos and Gaea. Another could be Percy teaming up with some unexpected allies from the realms of Kronos and Gaea to fight a new common enemy. Maybe Percy discovers a hidden prophecy that involves his lineage as the son of Kronos and Gaea and has to fulfill it to save the world.
A great plot could also involve the OC forming an unlikely alliance. He could team up with some of Percy Jackson's friends, like Annabeth. They initially don't trust him, but as they face challenges together, they realize that he's not like his father. This alliance could lead to them facing off against an ancient evil that only the combined knowledge and powers of the OC and the other demigods can defeat.
Well, perhaps a plot where Percy has to enter Kronos' old lair to find a way to break a curse that is affecting his friends. He could face many challenges and traps there. Also, a plot where Percy discovers that Kronos had a secret plan that he now has to carry out, but it conflicts with his loyalty to the Olympians.