In the fanfiction, Percy's view of life and mortality would be completely different. He might not fear death as much as others do, and this could lead to some really interesting character development. For instance, he could be more reckless in some situations because he has a different understanding of what it means to die, or he could be more empathetic towards those who are about to die.
In this fanfiction, Percy's role in the prophecy could change. Instead of being the hero for the Olympians, he could be the one to bring a new order with his Titan powers. His connection to Poseidon would be strained or even broken. He would have to find new allies, perhaps among the other demigods who are also outcasts because of their different heritages. And his battles would be against different foes, not just the Titans' old enemies but also those who oppose the idea of a demigod with Titan blood.
Well, Percy could start to resent Poseidon and all things related to him. He might decide to leave Camp Half - Blood and try to make it on his own in the mortal world. But then he realizes that his demigod powers still draw trouble, and he has to find a new way to deal with it without relying on his father's name.
The fanfiction could also explore Percy's identity crisis. He's known himself as the son of Poseidon for so long, but now being the son of Gaea and Tartarus would shatter that identity. He would have to re - evaluate who he is, what his purpose is, and how he fits into the world of demigods. This internal struggle could be a major part of the story, with Percy constantly fighting against the darker impulses that come from his new parentage while also trying to find a place where he can be accepted and still be himself in some way.
In some fanfictions, if Percy Jackson becomes Death, he might gain the power to decide the fates of all beings. He could be seen as a very solemn and powerful figure, no longer the carefree demigod. His relationships with other characters would also change drastically. For example, his friends might fear him at first, but then come to understand his new role and the importance of it in the grand scheme of things.
Perhaps in this fanfiction, Percy has special powers related to death. He could be able to communicate with the dead or have an understanding of the afterlife. This would add a whole new dimension to his character and the adventures he could have. Like, he might be called upon to solve mysteries that involve the spirits of the past.
A 'Naruto After Death' fanfiction could show Naruto's journey in the afterlife as a way to bring peace to the souls of those who died with grudges. He could use his unwavering will and the bonds he formed in life to help resolve the negative emotions of these lost souls. He might also meet his parents in the afterlife and finally have a proper family time that was cut short in his living days.
Well, in some fanfictions, Naruto might encounter a mysterious creature in the Forest of Death. This creature could befriend him and teach him some unique skills or give him special powers that are not part of the original Naruto universe. For example, it could teach him how to communicate with animals, which would be really cool and useful in many situations. Also, there could be a situation where Naruto stumbles upon a secret training ground within the forest that was once used by a great ninja from the past. He could then use this training ground to enhance his skills further.
One possibility is that Naruto meets the personification of Death in this fanfiction. They could have an intense conversation about the value of life and death, considering Naruto has seen so much death and destruction in his own world. And perhaps Death gives Naruto a new mission related to the balance between the living and the dead.
Well, she could end up in a duel with a powerful Death Eater. Hermione is a very skilled witch, so it would be a great show of her magical abilities. Maybe she discovers a new spell during the fight that helps her gain the upper hand.
Well, they might initially be shocked to see each other. The past Percy could be amazed at how much the future Percy has changed and grown. Maybe the future Percy tries to give the past Percy some advice to avoid future mistakes.