If Percy Jackson was captured by the Avengers in fanfiction, at first, the Avengers would likely be very cautious. They don't know his powers or his origin. Percy, on the other hand, would be scared but also defiant. He has his own world of demigods and monsters to deal with. He might initially resist the Avengers' attempts to hold him. However, as time goes on, he could start to understand their motives and they could start to understand his. This could lead to a mutual respect and a possible alliance against a common enemy, like some powerful monster from Percy's world that somehow poses a threat to Earth in the Avengers' view.
Percy could use his water powers. He could summon water from nearby sources, like pipes or even the air if it's humid enough. With the water, he could create distractions, like water walls or waves to disorient the Avengers. Then he could make a run for it.
Percy has his speed and agility. In the fanfiction, he might be able to use his demigod reflexes to dodge all of the Avengers' attacks. He could then quickly move in for a counter - attack. Also, his sword, Riptide, is a powerful weapon. It can cut through almost anything. He could use it to cut through the Avengers' weapons or their defenses if he gets close enough.
Well, initially, the Avengers would be quite skeptical. I mean, they deal with high - tech and super - soldier stuff. But once Percy shows what he can do, like summoning a giant sea monster to help in a battle, they'd start to see the value. Iron Man would likely try to find a scientific explanation for Percy's powers and might even try to replicate them in some way. Captain America would appreciate Percy's courage and how he uses his powers for good, just like he does with his own abilities.
One way could be to have Percy Jackson's powers of being a demigod interact with the superpowers of the Avengers. For example, his ability to control water could be used in a joint mission with Thor's lightning powers. Maybe they are facing a common enemy that can only be defeated by combining their unique skills.
A possible fanfiction could involve a crossover where some of the Avengers are sent to Camp Half - Blood. Imagine Tony Stark trying to figure out how the magic at the camp works while also being highly amused by the whole concept of demigods. Steve Rogers could bond with some of the more heroic demigods over their shared sense of duty. Meanwhile, Percy and his friends have to keep an eye on the Avengers to make sure they don't accidentally disrupt the delicate balance of the camp. And then, they all have to face a threat that targets both the Avengers and the demigods, like a group of villains who want to steal the powers of both.
There are so many fanfictions out there that it's hard to determine if there's a popular one with this specific plot. The Percy Jackson and Avengers fanfiction communities are quite large, but this concept goes against the general heroic portrayals in both universes. It's less likely to gain widespread popularity, but it doesn't mean there aren't some well - written ones out there that a small group of fans might really like.
Another option could be Black Widow. She's very good at adapting to new situations and using her skills in different ways. For Percy, who is coming from a very different world, she could teach him how to be stealthy and use his powers in a more covert way. She could also help him with understanding the political side of the Avengers, like dealing with government agencies and such, which Percy may not be used to in his world of demigods.
In a fanfiction where Percy Jackson was captured by Voldemort, a lot of things could occur. Percy's friends from Camp Half - Blood would surely try to rescue him. They might team up with some of the more brave and good - hearted wizards from Hogwarts. Voldemort might be intrigued by Percy's unique abilities and try to study him. However, Percy would not go down without a fight. He could potentially call upon his father Poseidon for help, which could lead to some really epic and unexpected events. For example, Poseidon could flood Voldemort's lair if he knew where Percy was held captive, causing chaos among Voldemort's Death Eaters.
In some fanfiction, Percy might be captured by an ancient, long - forgotten deity who has a vendetta against Poseidon. This deity could be using Percy as a bargaining chip to get something from Poseidon. The story could then focus on how Percy's friends try to rescue him, facing all sorts of trials and challenges along the way. They might have to travel to the deity's hidden realm, which is filled with dangerous creatures and traps.