In fanfiction, this could lead to some really interesting crossovers. Maybe Percy's mom having Kryptonian abilities could mean she has super strength or heat vision in a hidden way. It could add a whole new layer to Percy's story, like how she protected him in ways that were not just normal human ways but with some Kryptonian - like powers.
Yes, there are likely some fanfictions out there with the concept of 'Percy Jackson is death'. Fanfiction writers often come up with unique and creative interpretations of existing characters. You can start by looking on popular fanfiction websites like Archive of Our Own or FanFiction.net.
Another common opponent could be other demigods from different cabins. For instance, a child of Ares who might have a more aggressive and straightforward fighting style compared to Percy. This would create an interesting dynamic as they have different powers and personalities but are still on the same side in the general scheme of things.
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.
In some fanfictions where Sally dies, it could lead to Percy being filled with a new kind of rage and determination. He might become more withdrawn at first, shutting out his friends as he grapples with the loss. But eventually, it could fuel his growth as a hero, making him more fearless in the face of danger because he has already lost the most important person to him.
Nico di Angelo has a strong connection to the Underworld, so he's a prime candidate. He can already communicate with the dead and has some control over the shadows, which are related to death in a way. In fanfiction, he could be further developed to become the Master of Death, perhaps by making a deal with Hades or finding a hidden power within himself.
Annabeth could be a strong ally. She's always been by Percy's side, and her intelligence would be crucial in helping Percy navigate his new role as the son of death. She could research ancient texts to find out more about the powers and responsibilities that come with it.
The other characters would be devastated. Annabeth, for instance, would be heartbroken. She has been through so much with Percy, and his death would leave a huge void in her life. She might become more withdrawn and less trusting. Grover would also be deeply affected. He has been Percy's friend since the beginning, and he would probably blame himself for not being able to protect Percy. The other demigods would lose their hero, and they might feel less confident in their ability to defend Olympus.
One popular 'Percy Jackson Mom Fanfiction' story could be one where Percy's mom has hidden powers that are revealed during a new threat to Camp Half - Blood. It adds an interesting layer to her character.
Perhaps he has lost too many people close to him. If his friends, like Annabeth or Grover, were to die in a particularly tragic way, he could be so grief - stricken that he no longer wants to live in a world without them. He might think that death is the only way to escape the pain of their loss.