Annabeth would probably be very worried and take charge. She'd start researching immediately, looking through books in the camp library to find a cure. Grover would be constantly by Percy's side, using his nature - related powers to try and make Percy more comfortable, like bringing in fresh air and plants to help him feel better.
In this kind of fanfiction, one scenario could be that Will Solace uses his healing powers to try and cure Percy. He might be really worried as Percy is not only his friend but also someone he cares about deeply. Maybe he brings Percy to the infirmary in Camp Half - Blood and stays by his side, constantly checking on his condition and using his medical knowledge and powers to make Percy better.
It could be a jealous demigod. Maybe someone who has always been envious of Percy's popularity and abilities. Now that Percy has wings, this demigod sees it as an opportunity to make Percy look bad. They spread rumors that Percy's wings are a sign of him being cursed by the gods and try to turn other demigods against him while he's already feeling sick and struggling with his new wings.
In this 'Percy Jackson Gets Wings' sick fanfic, it could be that Percy gets wings as a gift from an unknown god. But the wings come with a curse that makes him sick. He starts having visions whenever he tries to fly. These visions show him some dark secrets about the gods. Percy has to figure out what the visions mean and how to break the curse while also learning to control his new wings. He might go on a journey to consult the Oracle or some other wise beings in the demigod world.
Well, one possibility is that Percy's friends try to find a cure. Maybe Annabeth uses her wisdom to research in the library of Camp Half - Blood while Grover tries to use his nature - related powers to find some special herbs. And Percy is just lying in his cabin, feeling really weak and feverish.
One common theme is the vulnerability of the characters. Percy, who is usually strong and heroic, becomes weak when sick, showing a different side of him. For example, in many fanfictions, he might struggle to even stand up or use his powers.
One possible scenario could be that in the fanfiction, the sick person is a demigod who has been poisoned during a quest. Percy Jackson and Will Solace team up to find a cure. Percy uses his water - related powers to purify some of the ingredients needed for the antidote, while Will Solace, with his healing skills, tries to keep the sick demigod stable. They face various obstacles along the way, like monsters trying to stop them from reaching the final ingredient. In the end, they manage to save the sick demigod and strengthen their friendship.
Perhaps it's a gift from his father, Poseidon. Since Poseidon has control over the sea and all things related to water, he might have some connection to a power that gives Percy wings, like as a way to help Percy reach new heights both literally and metaphorically.
Obviously, Percy would be the main character as the story is about him getting sick. But his friends like Annabeth and Grover would also be important characters. They would be the ones trying to help Percy get better, so they play a big part in the fanfiction.
Well, maybe Percy could be poisoned by a monster in disguise at school. He starts feeling really sick, like having a high fever and being super weak. His friends, like Annabeth, suspect something is wrong and start investigating. They might find out that there's a new threat in the school that's targeting demigods.