Ice powers could fit in by being a new type of power that challenges the existing power dynamics. For instance, in battles, they could change the terrain by creating ice ramps or freezing lakes for strategic advantages.
Percy's powers would be a great addition to the Avengers in a fanfiction. His control over water could create a lot of strategic opportunities. He could flood an area to slow down enemies or create ice platforms for the Avengers to stand on during battles. Compared to Captain America's leadership and combat skills, Percy could offer a different kind of support. And when it comes to Thor, while Thor controls lightning, Percy could use water to conduct that lightning in different ways for more powerful attacks.
Well, he could be a messenger in the fanfiction. Just as he is often depicted as a messenger in religious texts, he could bring important news from the celestial realm to the demigod world. Maybe he warns Percy about a new threat that is coming from a place that the demigods have no knowledge of. And his presence could stir up a lot of questions among the characters about different mythologies and how they all connect.
Percy's water - controlling powers could be a great asset in the SHIELD universe. For example, in a situation where there's a flood or a water - based attack by an enemy, he could easily manipulate the water to turn the situation around. His powers might also be useful in interrogations. He could create a water - based illusion or something similar to intimidate the bad guys.
There could be a fanfiction where a character with ice powers is actually an enemy in the Percy Jackson world. They are trying to freeze over all the water sources, which would be a huge threat to the demigods. Percy and his friends have to figure out how to stop this ice - powered foe. They might discover that the only way is to find a way to combine fire and water powers in a unique way, like using the heat from Hephaestus - forged weapons along with Percy's water control to melt the ice and defeat the enemy.
Naruto's chakra powers could be a great addition. His Rasengan could be like a new type of energy attack for the Avengers. Maybe he could combine it with Thor's lightning for an even more powerful blast.
In fanfiction, the possibilities are endless. The demigods could introduce magic in a more widespread way in the DC Universe. Imagine Annabeth's strategic mind being used to plan against the likes of Lex Luthor. Her knowledge of architecture and ancient wisdom could give the DC heroes an edge in battles that require more than just brute force. Also, the presence of demigods could lead to new storylines about the origin of some of the DC magic - related elements.
Annabeth, with her intelligence and strategic mind, could become an advisor to the Rebel Alliance. She could help them plan battles and fortifications, much like she did in the Percy Jackson series against the Titans. Grover, being a satyr, could befriend some of the more nature - based species in the Star Wars universe, like the Ewoks. He could communicate with them and help them understand the threat that the Empire poses to their way of life.
Well, it could be a really interesting and terrifying addition. Maybe it could be some kind of ancient monster that was locked away long ago in the world of Percy Jackson. It could be released by some dark magic or an evil demigod. The xenomorph's ability to adapt and its deadly nature would make it a formidable foe for Percy and his friends.
His water - based powers could be used in unique ways. For example, he could create water barriers around Slytherin's common room for protection. His control over water could also be used in dueling practice, teaching Slytherin students new defensive and offensive techniques.
He could be a mentor figure. Given his immortality and vast combat experience from the Naruto world, he could teach the demigods new ways to fight and strategize.