Well, perhaps in this fanfiction, Percy Jackson is sent on a time - travel mission by the gods. But he discovers that his friends or allies have betrayed him. Maybe they've made a deal with an enemy from another time period. For example, they could have promised to help Kronos in the past in exchange for power in their own time. Percy then has to not only deal with the time - travel chaos but also face the betrayal and find a way to set things right.
One possible plot for this fanfiction could be that Percy is betrayed by a new character introduced in the fan - made story. This new character pretends to be his friend, gains his trust, and then reveals their true evil intentions. They lead Percy into a trap set by some ancient and deadly enemies. Percy, caught off - guard, is then killed. This would add an element of mystery and new drama to the familiar Percy Jackson universe.
Well, it could be about Percy finding out that a god he trusted has betrayed him. Maybe this god has been using Percy for their own gain all along, like in battles against other gods or monsters. Percy would then have to deal with the shock and figure out how to either get revenge or make things right in the world of the gods.
One possible plot could be that Percy is betrayed by one of his closest friends in Camp Half - Blood. Maybe Annabeth turns on him out of jealousy over his growing powers or a misunderstanding. Percy, feeling deeply hurt, decides to disappear into the mortal world. He cuts off all ties with the demigod community and tries to live a normal life, but his past keeps haunting him as monsters still sense his presence.
One possible plot could be that Percy Jackson, in a crossover world, is somehow made to believe that the Twilight characters are a threat to his world. Maybe he's deceived by some dark force into thinking they're planning to take over Camp Half - Blood. So he betrays them by leading an attack on their territory in Forks, not realizing he's been tricked.
Well, it could be that Percy is tricked into believing the son of chaos is a threat when he's actually not. Maybe some other characters manipulate Percy's perception with false evidence.
The sister could be under the control of a powerful god or goddess who has a grudge against Percy. She might be forced to betray him. For instance, she could lead Percy into a trap set by the god. She could lie to him about a mission, saying it's a rescue mission but in fact it's a trap where the god is waiting to take revenge on Percy for some past deeds. This would be a really heart - breaking betrayal for Percy as he trusts his sister.
There's a chance that it could be a character from Percy's family. For example, a distant relative who has been corrupted by some dark magic. They might betray Percy for their own gain or because they are being controlled, and this betrayal could lead to Percy being killed.
One great 'Percy Jackson Time Travel Fanfiction' is 'Time Warped'. It takes Percy back to ancient Greece and he has to deal with all kinds of challenges that are different from his modern - day ones. He meets his ancient relatives and has to figure out how to get back to his own time without changing history too much.
One great 'Time Travel Percy Jackson Fanfiction' is 'The Time - Traveling Demigod'. It has an exciting plot where Percy is sent back in time and has to deal with all kinds of challenges that change his understanding of his own world. The author does a great job of keeping Percy's character consistent while also showing how he grows through these new experiences.
One idea could be Percy accidentally travels back in time and encounters Chronos in his prime. Maybe he has to team up with some of the old - time demigods to stop Chronos from an early attempt at world domination. It would be full of action and adventure as Percy tries to use his modern skills in an ancient world.