One possible reason could be that Percy values his humanity. He has seen the flaws of the gods and doesn't want to be like them. In the original series, he has had many experiences with the gods' self - centeredness. So in fanfiction, he might turn down godhood to stay true to his mortal self.
His decision might give hope to other demigods. They see that it's possible to be content without striving for godhood. For example, some demigods who might have been jealous or envious of Percy could now see that there are other paths to a fulfilling life.
Perhaps he's seen the downsides of being a god in the Percy Jackson universe. Gods are often restricted by their domains and have a lot of responsibilities. Percy, who has always been a bit of a rebel, might not want to be tied down by such rules. He likes his freedom to make his own choices and help people in his own way, not in the way a god is expected to.
Well, it really depends on the specific fanfiction. There are countless fanfictions out there about Percy Jackson. Some authors might choose to elevate him to god status as a way to explore different aspects of his character, like how he would handle immortality or the responsibilities that come with being a god. They could also do it to create interesting new power dynamics within the Percy Jackson universe.
One idea could be that Percy turns into a dragon to fight a powerful sea monster. Since he has his connection to water, as a dragon he could breathe a sort of water - based fire or ice that freezes the water around the monster, trapping it.
Yes, in some fanfiction, Percy Jackson can be depicted as a fan of Norse gods. Fanfiction often takes existing characters and places them in new and different scenarios or gives them new interests. So it's possible for Percy Jackson to be into Norse gods within the creative realm of fan - made stories.
Some fanfictions might explore what would happen if Percy had a different parentage. Maybe he was the son of a different god or goddess, like Hecate. This would completely change his powers and the way he interacts with the magical world around him. He could learn new types of magic and have a whole new set of challenges and adventures.
In a 'Percy Jackson turns evil' fanfiction, he might use his powers against his former friends. For example, his control over water could be used to flood Camp Half - Blood. His knowledge of the demigod world would also be a weapon in his hands to outwit and defeat those who oppose him.
Well, in the fanfiction, if Percy turns into a baby, he would probably lose all his skills and knowledge at first. But he might still have some instinctual connection to water. Maybe his friends like Annabeth would have to take care of him. She'd be really protective and try to find a way to turn him back.
In the 'Percy Jackson turns into a cat' fanfiction, he could end up in some really interesting situations. For example, he might be chased by some of the magical creatures at Camp Half - Blood that don't recognize him as Percy. His senses would be heightened as a cat, so he could detect things like danger or hidden treasures more easily. Also, it would be hilarious to see how Annabeth reacts when she first sees Percy as a cat. She might be confused at first but then try to figure out how to turn him back.