A possible plotline could be Percy being sent to a different realm, like the Underworld in a more extreme state, to redeem a lost soul. In this journey, he would encounter various challenges and meet new characters. He might have to bargain with Hades in a different way and face his own fears about death and the afterlife. Along the way, he could discover new powers or aspects of his heritage that help him in his quest.
Maybe a plot where Percy has to redeem himself in the eyes of a group of demigods who have been wronged by his past actions. He would have to go through a series of trials to prove that he is truly a changed hero and worthy of their trust again. This could involve him making amends and learning more about the consequences of his actions.
One interesting plotline could be Percy having to face a new and powerful ancient evil that the gods are also afraid of. This would put him in a position where he has to use his wits and powers in ways he hasn't before.
One interesting plotline could be the Seven facing a new, more powerful enemy that is a combination of different mythological creatures. This would test their teamwork and individual powers in new ways.
One interesting plotline could be Aphrodite taking a special interest in Percy for a quest related to love and beauty. Maybe she tasks him with finding a lost artifact that has the power to enhance or destroy love. Another could be Percy falling under a love spell cast by Aphrodite, which causes chaos among his friends as he starts acting out of character. And a third one might be Aphrodite using Percy as a pawn in a love - related game among the gods, where his actions and decisions have far - reaching consequences for the relationships between the deities.
One interesting plotline could be the siblings going on a secret quest together without the knowledge of Chiron or the other campers. They might face a new and unknown monster that tests their combined skills.
In some fanfictions, a centurion discovers a long - lost prophecy that involves Percy. This could lead to a race against time as they try to figure out the meaning of the prophecy and prevent a great disaster. Maybe it involves a new Titan rising and they need Percy's unique connection to the sea gods to stop it.
Maybe in the fanfiction, Percy's player side shows up when he has to navigate the complex social hierarchies of the demigod world. He could be seen charming different groups of demigods, from the children of Athena with his quick - witted remarks to the children of Aphrodite with his newfound 'player' charisma. This could lead to all sorts of adventures and conflicts as he tries to maintain his relationships while also keeping up his player image.
Another plotline could be Percy trying to find a way to clear his name and escape the prison. Along the way, he might make some unexpected allies among the inmates or even some prison staff who are sympathetic to his cause. This could lead to an epic adventure within the prison walls as he tries to gather evidence and outwit his captors.
One interesting plotline could be Percy trying to find a way to return home while facing new and unexpected challenges in his exile. He might encounter strange creatures or make new allies.
One interesting plotline could be a yandere character becoming overly possessive of Percy. For example, they might try to isolate him from his friends at Camp Half - Blood, seeing them as threats to their 'relationship' with Percy. Another could be a yandere secretly sabotaging Percy's quests out of the fear of losing him. They think that if he doesn't go on these dangerous quests, he'll be safe and stay with them.
A possible plotline could be that the hermit is actually a forgotten hero from the past. He has been in hiding all this time but now his past is catching up with him. As he tries to keep his identity a secret, events unfold that force him to face his former life and the consequences of his actions long ago.
Another plotline could involve Percy's relationships with other characters. Maybe he has to face some of his old friends who now see him as a threat because of his association with chaos. Or perhaps he forms new alliances with characters who are also on the side of chaos, but they have different motives.