I'm not sure if there is a specific fanfiction exactly like that. Fanfiction can cover a wide range of themes and scenarios, but this seems a bit of an unusual one. You could try searching on major fanfiction websites like Archive of Our Own or FanFiction.net to see if such a story exists.
Perhaps in a fanfiction, Percy is magically transformed into a different form that includes wearing a sexy dress. He then has to navigate the world in this new form while his friends are trying to figure out how to reverse the spell. Along the way, he discovers new things about himself and the way others perceive him. It could also involve some comical situations as he tries to move around and fight in the dress. Another plot could be that it's part of a bet or a dare within the demigod community. Percy, being the brave one, accepts the challenge of wearing the dress for a day or an event, and during this time, he has all sorts of adventures and interactions with other characters that he wouldn't have had otherwise.
One possible plot twist could be that Percy wearing a dress is part of a disguise to infiltrate a group that only allows females. For example, he might be trying to retrieve a powerful magical item that is guarded by this all - female group. Another plot twist could be that it's a magical curse that forces him to wear a dress until he completes a certain task, like solving a riddle or making amends with a certain deity. And perhaps the dress is enchanted and gives him special powers that he has to learn to use while also dealing with the embarrassment of wearing it.
As a punishment. He could have angered a powerful being, like a minor god or an elder at Camp Half - Blood, who decides that wearing a dress is a fitting form of humiliation for his misdeeds.
Annabeth would probably be a mix of amused and exasperated. She might tease him a bit at first but then help him out if he's in an uncomfortable situation because of the dress. Grover would be really shocked at first but then try to be supportive. He might say something like 'Well, Percy, you look... different, but it's okay!'. As for Tyson, he would just be happy to see Percy and not really care about the dress all that much.
Perhaps it's a bet gone wrong. Percy loses a bet to one of his friends, like Grover, and as a result, he has to wear a dress for a whole day at Camp Half - Blood. This could lead to a lot of teasing and also some interesting character development as he has to face his own pride and the reactions of others.
No. Percy Jackson is an original fictional series. Although it uses Greek mythology as its base, it has created a completely new world, characters, and storylines. Fanfiction usually implies building upon an existing work in a more derivative way, often by fans rather than the original creator. 'Percy Jackson' was created by Rick Riordan as an original concept.
In Percy Jackson fanfiction, families can be depicted in various ways. Some might show Percy's family having new and unexpected adventures together. For example, his mom could discover a new magical ability that she uses to protect the family from an ancient threat. Another idea could be that Percy's half - brother Tyson becomes a key figure in protecting the family from monsters that target them specifically because of Percy's fame among the demigods.
One idea for a Percy Jackson famous singer fanfiction could be that a famous singer is actually a demigod in disguise. Maybe they use their music as a form of magic or to communicate with other demigods secretly. For example, their lyrics could hold hidden messages about upcoming quests or threats to the demigod community.