One possibility is that the fanfiction could explore the growth of Percy and his friends' relationships. Since they have crushes on him, they might be more motivated to be better versions of themselves. For example, they could study harder if Percy values intelligence, or become more athletic if that's what Percy admires. At the same time, Percy might be flattered but also a bit confused, and he'd have to navigate through his own feelings about his friends while maintaining the friendships.
He could also be very kind and gentle in his reaction. Percy might not want to hurt his friends' feelings, so he'd try to let them down easy if he doesn't feel the same way. He might say something like 'You're a great friend, and I value our friendship so much' to show that he cares about them but not in that romantic way. On the other hand, if he has some hidden feelings for one of them, he could start to show more interest in return, like spending more time alone with that friend.
Another possibility is that Percy is flattered. He respects Thalia a great deal and having her have a crush on him could boost his self - esteem. He might start to be a bit more aware of her presence and try to be nicer to her. For instance, he might start sharing his food with her during meals or offer to help her with her training. However, he could also be a bit confused because he might not have thought of Thalia in that way before.
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.
In many fanfictions, Piper's crush on Percy can add a lot of interesting drama. It might start with simple glances and stolen moments. Piper could be drawn to Percy's bravery and leadership. Their interactions can range from hesitant conversations to more intense emotional exchanges, depending on how the author wants to develop the relationship within the fanfiction world.
In fanfics, the writer has a lot of creative freedom. Percy's crush could be a completely new character created by the author just for this story. Or it could be an existing character that has a different relationship with Percy in this fan - created narrative. For example, it could be a minor character that the author decides to develop a romantic plotline for with Percy.
Annabeth would be furious. She would immediately confront Jason, demanding an explanation. She's very protective of Percy and would not stand for him being hurt without a good reason. She might even suspect Jason of having some ulterior motives at first. Nico, on the other hand, would be more reserved but equally angry. He would keep a close eye on Percy's recovery and might even be tempted to use his powers to seek revenge on Jason if Percy's condition was serious.
His friends could start by trying to figure out what caused the transformation. Annabeth might use her wisdom to research in the library at Camp Half - Blood. Grover could use his connection to nature to see if there are any magical plants or creatures that could reverse it. And the other demigods could keep Percy safe from any potential threats while he's in his cat form.
Athena might also be a good candidate. Although she and Poseidon have their differences, she could see Percy's potential and befriend him. She could offer him wisdom and strategic advice for his various adventures.
He could be friends with Neville. Neville is kind - hearted and they might bond over their shared experiences of feeling a bit out of place at Hogwarts. Another friend could be Luna. She has an open - minded and unique personality, and she would likely accept Percy for who he is.