In this 'jace gets sick fanfiction', Jace is the one who gets sick, of course. But there might also be his family members. For example, his mother could be a very important character, hovering over him, making sure he takes his medicine and gets enough rest. And perhaps there is a wise old doctor in the story, who tries different remedies to cure Jace.
Obviously Elsa herself would be one of the main characters since she is the one getting sick. Anna would also be a main character as she would be very concerned about Elsa's condition and would do everything she can to help. Olaf could also play an important role, using his cheerfulness to try to make Elsa feel better.
Obviously, Bendy would be one of the main characters since he's the one getting sick. His friends like Boris and Alice would also be main characters as they would likely be involved in taking care of him or finding a cure.
Mario would most likely be a main character too. He's Luigi's brother, so he'd be there to take care of him or at least be really worried about him. Princess Peach could also be a main character. She might visit Luigi when he's sick and bring some kind of magical item that could potentially help him get better.
In the 'jace gets sick fanfiction', it might involve Jace getting a mysterious illness. This leads to a search for a cure, with his family and allies scouring the land for rare herbs or magic spells to heal him. They face many challenges along the way, such as dangerous creatures guarding the ingredients they need.
Obviously, Death the Kid himself would be the main character. He's the one who's sick after all.
In this fanfiction, not only her immediate family and friends but also neighbors or classmates could be involved. Neighbors might offer help like bringing over some home - made remedies. Classmates could be concerned and send her get - well - soon cards or come to visit her after school. And if there are any pets in Ginny's life, they could also play a role, like staying close to her and providing some comfort.
His friends like Batman and Nightwing could be main characters. Batman might use his detective skills to figure out what's wrong with Robin, and Nightwing could be there to offer emotional support.
Since Rigby is sick, his family members could also be main characters in the fanfiction. They might come to visit him and bring their own unique family drama to the story. And his friends from the park, like Muscle Man and High Five Ghost, could also be involved, trying to cheer him up while he's ill.
Seth could be the one to help her. As her brother, he would be very concerned and might use his own knowledge of Fablehaven and its secrets to try and find a cure. He could also enlist the help of some of the friendly magical creatures they've befriended, like the fairies or the satyrs.
His teammates, Sasuke and Sakura, would surely be involved. Sasuke, although he may not show it as much, still cares about Naruto. He would keep an eye on Naruto's condition, and if there was any sign of danger, he would be ready to protect him. Sakura would be more hands - on with the medical care, checking his temperature, giving him medicine, and making sure he rests properly.