Maybe he feels guilty. Suppose he made a big mistake, like accidentally leading an enemy to a safe haven of demigods. The guilt could be so overwhelming that he exiles himself to punish himself and keep others safe from his potential future blunders.
It could also be due to a loss of faith in himself or his abilities. If he fails in a major task, like not being able to save someone important, he might lose confidence. He may believe that he is no longer worthy to be among his peers and thus exile himself.
It could also be due to a sense of guilt. If something bad happened that he blames himself for, like someone getting hurt because of him, he might exile himself as a form of self - punishment. He'd rather be alone and deal with his own pain than face those he feels he's let down.
Redemption is also a big theme. Some fanfics show Percy trying to redeem himself for something he may or may not have done wrong. Also, the theme of friendship is still present even in exile. His friends may be trying to find him or he may be making new friends in his exile state.
Some fanfiction writers may do it to stand out. Since the Percy Jackson series is so well - known, creating a version where he is a devil can attract attention. Also, it could be a way to explore darker themes. The original series has a lot of heroic and positive elements, but in fanfiction, making Percy a devil allows for a look at the other side of the coin, like how his powers could be used for evil instead of good.
In fanfiction, Percy being rich might be a way for the writer to explore different aspects of the Percy Jackson universe. Maybe they want to show how the world of demigods would interact with wealth. It could also be a way to make Percy more like a modern hero, who often has access to a lot of resources. Plus, it can lead to comical situations where Percy, who is used to a more simple life, has to deal with the trappings of being rich, like dealing with butlers or managing a large estate.
His friends would be devastated. They rely on him a great deal. Annabeth, for instance, would be heartbroken and would probably try to find him. Grover would also be very concerned and might use his nature - related abilities to search for Percy.
His friends would be devastated. They rely on Percy in many ways, and his sudden absence would leave a big void. For instance, Annabeth might feel lost without him, as they have a deep connection. She would probably be very worried and try to find him.
He could be a loner because he lost someone very close to him. This loss makes him shut everyone else out as he feels that no one can understand his pain. For instance, if Annabeth were to die in some tragic way, Percy might retreat into himself and avoid the company of others.
One possible reason could be that Percy has shown some extraordinary power that even Thor, a powerful god, respects. Maybe Percy has defeated a common enemy in a really remarkable way that makes Thor recognize his strength and kneel in admiration.
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.
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.