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 he wants to change the system. Percy has always been a bit of a rebel, and in fanfiction, he could see the gods' rule as corrupt or unfair. So, killing them could be his way of starting anew and creating a better world for demigods and mortals alike. Another motive could be to prevent a greater evil. If he discovers that the gods are planning something that would destroy the world, he might decide that killing them is the only way to stop it.
Well, Percy is used to strange things, but the multiverse would still throw him for a loop. In the fanfiction, he could start off being skeptical. After all, he's been through a lot in his own world, and the idea of countless other versions of his reality seems far - fetched at first. But as he delves deeper, he might start to see parallels between his world and the other universes in the multiverse, which could make him more accepting.
Well, sometimes in fanfiction, his brother might be a mortal who discovers his demigod heritage later. This could add an interesting twist to the story as he has to adapt to the world of gods and monsters. Or it could be a long - lost half - brother from a different camp, like a son of Poseidon from another part of the world who was hidden away for some reason.
In Percy Jackson fanfiction, families can be depicted in various ways. Some might show Percy's family having new and unexpected adventures together. For example, his mom could discover a new magical ability that she uses to protect the family from an ancient threat. Another idea could be that Percy's half - brother Tyson becomes a key figure in protecting the family from monsters that target them specifically because of Percy's fame among the demigods.
The characters. Percy is a relatable hero with flaws and a great sense of humor. His friends, like Annabeth and Grover, are also very interesting and each has their own unique abilities.
He might be shocked and a bit disturbed. Percy is a heroic character, and seeing a 'dark' version of himself in fanfiction would be quite jarring. It's like looking into a distorted mirror of his identity.
Maybe he faced an extremely powerful enemy that he couldn't overcome. It could be a new and terrifying monster created by the Titans or some other dark force.
Annabeth Chase would most likely be one of his allies. She has always been by Percy's side, and she shares his sense of justice. If Percy decides to take on the gods, she would be there to support him with her intelligence and strategic thinking.