If Percy Jackson goes to Middle Earth in a fanfiction, he would bring his own brand of heroism. He's used to facing big challenges, like the Titans in his own world. In Middle Earth, he could face the Dark Lord. His sword skills and his ability to think on his feet would be assets. And his sense of loyalty would make him a great ally to the free peoples of Middle Earth. He might also introduce some new ideas from his world, like different fighting techniques or ways of using water in combat.
Percy would probably find the different cultures in Middle Earth fascinating. He could team up with Legolas, for example. With Percy's quick reflexes and Legolas' archery skills, they'd make a great duo. Also, Percy's knowledge of Greek mythology might give him some unique insights when dealing with the magical creatures in Middle Earth. He might even try to find similarities between the Greek gods and the powers in Middle Earth.
Well, he might be really confused at first. Middle Earth has its own rules, magic, and races. Percy, with his water powers, could have some interesting interactions with the rivers and seas in Middle Earth. Maybe he'd help the Fellowship in some way, like using his powers to create distractions during battles or to cross dangerous water areas.
In fanfiction, if Percy Jackson goes to highschool, he might face challenges like hiding his demigod powers from his classmates. He could also encounter new mythical creatures that are drawn to the school environment.
In a fanfiction where Percy Jackson goes to Azeroth, he could form alliances. Since he's used to being in a team in his own world, he'd likely team up with some of the heroes in Azeroth. For example, he could join forces with Thrall and help him in his quest for the Horde. His sword - fighting skills from Camp Half - Blood would come in handy in battles against the Burning Legion or other enemies.
If Percy Jackson goes to UA, there would be a huge culture clash at first. The UA students are used to a very structured hero training system, while Percy is more of a 'go with the flow' kind of demigod. But over time, he could teach them about improvisation in battle and they could teach him about teamwork in a more organized way. He might also introduce the concept of Greek mythology to the UA world, which could open up new ways of thinking about powers and abilities.
Well, he might get into all sorts of adventures. He could meet the dragons in Alagaesia and try to use his water powers to his advantage against them. Maybe he'd team up with the local heroes there and learn new combat styles.
Perhaps Percy would see a future where the monsters have evolved in strange ways. They could be more intelligent and organized, posing an even greater threat to the demigods. He might also find that some of his old friends have made great sacrifices and that he has a new role to play in this future world, like being a mentor to the new generation of demigods.
In this fanfiction, Percy might decide to break away from Camp Half - Blood. He could start exploring the mortal world on his own terms, using his demigod powers in ways that the camp rules don't allow. Maybe he teams up with some unexpected allies, like a group of outcast demigods or even some friendly monsters.
In this fanfiction, perhaps Percy will make new friends at Goode who end up getting involved in his demigod world. There could be a plot where the school is in danger, and Percy has to use his powers and knowledge of the mythological world to protect it. Maybe he'll also have some interesting interactions with his teachers who suspect there's something different about him.
Perhaps in this fanfiction, Percy goes to Australia to find a hidden artifact that is crucial for the safety of the demigod world. Along the way, he teams up with local demigods (if there are any in the fan - created story). He would have to adapt to the Australian culture and environment, which is very different from what he's used to in the US. He might also face some new types of monsters that are native to Australia.
In a fanfiction where Percy Jackson goes to Forks, he might be really confused by the gloomy weather. He's used to more sunny and open places. He could meet the Cullens and there would be a clash of his demigod powers and their vampire abilities. Maybe he'd mistake them for some new kind of monster at first.
Well, he might meet Elsa and be really amazed by her ice powers. Since Percy is used to dealing with all kinds of magic in his own world, he could either help Elsa control her powers better or get into some trouble because of the different nature of the magic in Arendelle. Maybe he'd also team up with Anna to fight against some new threat that emerges in Arendelle.