Another aspect of Daki fan fiction could be the alternate universes. What if Daki was never a demon? How would her life be? These are the kinds of creative ideas that can be explored in fan fictions, and they often attract fans who want to see different interpretations of the character.
One main element is his difficult upbringing in poverty - stricken surroundings. Another is the constant bullying and discrimination he endured due to his physical appearance. And of course, his strong bond with his sister Daki. This bond was what drove him to protect her at all costs and also influenced his actions as a demon. For example, he would go to great lengths to avenge any harm done to her because of their shared experiences of being outcasts in society.
One popular theme is redemption. Since Daki is a demon, some fan fictions might explore the idea of her finding a way to redeem herself. This could involve her making amends for the harm she has caused to humans.
Gyutaro was born into poverty. He and his sister Daki had a very tough life. They were constantly bullied and looked down upon. Gyutaro had a deformed body which added to his misery. He was filled with hatred towards the world that treated them so badly. In order to protect his sister, he became extremely violent and cruel to those who he thought were threats. His experiences in his early life shaped him into the demon he later became, using his powers to lash out at those he despised.
He would probably be quite amused by some of his past antics. For example, his constant pranks on Iruka-sensei. But at the same time, he'd also see the pain he carried from not having his parents and realize how that influenced his actions. He might react with a bit of regret for some of the stupid things he did out of loneliness, but also be glad that those experiences made him who he is today.
Well, some past gods might be amused. They'd see these modern interpretations of their stories and characters in the Percy Jackson fanfiction as a strange yet interesting new form of worship or at least attention. For example, Zeus might be a bit irked at some of the liberties taken with his character, but also secretly flattered that people are still so interested in him.
Captain America would probably be very reflective. He might see his past self as a reminder of his long journey and how much he has changed. He could try to offer some words of wisdom to his younger self.
Well, Boruto could be very inspired. Naruto's past is full of struggles, from not having parents around to being constantly underestimated. When Boruto discovers this in the fanfiction, he might realize that his own problems are not as big as he thought. He could be motivated to work harder and not take for granted the things he has, seeing how much Naruto had to fight for everything.