Sometimes, established fanfiction writers who are well - known in the PJO fan community might take on such an interesting concept. They might have a large following already and decide to explore this new and strange idea of Percy having a tail to offer their readers something different and engaging.
It could be a group of fans who collaborate on the story. They might each contribute different parts or ideas. For example, one person could be good at writing action scenes, another at character development, and they come together to create this 'Percy has a tail' fanfiction.
Perhaps it's a curse or a spell gone wrong. In the world of PJO, there are many magical mishaps. It could be that someone intended to harm Percy and this was the result. Or it could be a side - effect of a powerful artifact he came into contact with.
One common theme is adventure. Percy is always going on some sort of journey or quest. Another is friendship, as he relies on his friends like Annabeth and Grover. And of course, there's the theme of power, especially related to Percy's unique abilities which might be emphasized more in fanfics about his tail.
If Percy is exiled in this PJO Avengers fanfiction, it could lead to some really interesting story developments. Since he's used to having his friends and allies around in the Percy Jackson series, being alone in the Avengers' world would be a big change. He might start to discover new powers or abilities as he struggles to survive. And there could be a whole plot about him trying to prove his worth to the Avengers so he can be accepted back.
The plot could involve Percy waking up one day and finding a tail instead of his legs. At first, he's confused and a bit scared. But then he realizes it gives him some new abilities, like super - fast swimming. He could then go on a quest where his tail is both an advantage and a hindrance. For example, it might be hard to move on land, but in water, he can out - swim any monster.
One popular Percy Tail PJO fanfic is 'The Lost Hero's Quest'. It takes the characters on a new adventure filled with mystery and danger. Another great one could be 'Percy and the Underworld Revisited' which delves deeper into the relationship between Percy and the Underworld. There's also 'Tail of the Titans' that has an interesting take on the battles against the Titans from Percy's perspective.
Obviously, Percy would be the main character. But there could also be his best friend, let's say Jack, who helps him through the whole ordeal of growing a tail. Maybe there's a wise old mentor figure, like an old wizard named Merlin, who has some knowledge about such strange transformations.
A big theme is also about power and responsibility. As a mercenary, Percy has power in his skills and abilities, but he also has the responsibility to use them for good. In many fanfictions, he struggles with how far he can go in his mercenary work without compromising his values. For example, he might be offered a large sum of money to do something that goes against his moral code, and how he deals with that is a central part of the story. This theme is explored in different ways in different fanfictions, sometimes more subtly and sometimes more directly.
Well, perhaps Percy is a character in a magical world. He could have been cursed or exposed to some strange magic that causes him to grow a tail. Maybe it starts as a small, furry growth that he tries to hide, but as the story progresses, the tail takes on a life of its own and gives him unique abilities like climbing better or sensing danger.
Maybe it could be a new character. A mysterious woman who Percy meets during one of his adventures. This would add an element of mystery to the story.
One possible plot could be Percy trying to find a way back home. He might have to complete certain quests or tasks set by the Avengers or some other powerful entity in the fanfiction world. Another plot could be Percy getting involved in a conflict that he wasn't originally a part of because of his exile, like a battle between different superhero factions.