Getting sick might be his worst nightmare.
There was just something about the feeling of his body not working properly. Of having something ultimately wrong with him and not being able to do anything about it. He would take his medicine, pray for Apollo, and wait for it to pass. That made him uneasy. Jaehwan was a problem solver, be the issue his or the islanders. There was no waiting around for the solution to fall in his lap, for things to just happen overnight. He makes them happen. But there was nothing more he could do in this situation.
More than anything... getting sick made him whiny.
There was no way around it. Doesn't matter how much it made him feel like a little kid, or how it felt ridiculous to suddenly feel the need to be taken care of, sickness equated to clinginess. That was simply not who he was. Jaehwan was a leader (not by choice), he was headstrong, he was the island protector, he was the human that told vampires to fuck off because they were being assholes. He was Apollo's favorite devotee (self-appointed and never confirmed). He embraced the supernatural. Jaehwan was, if he could say it himself, a fucking badass. Now he just felt like an infant.
Usually, he would just ride it out by himself. Asking for his parents was not an option, they would usually do more harm than good. Start to ask if he thought it was a curse, if he was not doing his rituals properly, or any other type of bullshit before considering that, sometimes, a cold is just a cold. None of his neighbors would be any type of help either. If Jaehwan got sick it was not about him, it was about them. About how he would not be capable of attending to their needs. He would usually just ask for some food, say he was doing a cleansing ritual, and disappear for a couple of days. But now... now things were different. Now Jaehwan had a boyfriend, a boyfriend that could not get sick, and that could very much come over to spoil him and be his personal pillow for the rest of the day -- he was also really cold, very useful for getting one's fever down.
Jaehwan disentangled a single arm from his blanket cocoon, enough to pat around until his hand came into contact with the hard surface of his phone. He barely had to wait for Hyuk to pick up the phone, but as soon as he did, a coughing fit stopped him from saying anything for a couple of seconds. " -- hyung..." his voice was croaky, so soft he doubted anyone else would be able to hear it over the phone. If he lost his voice too Jaehwan was pretty sure he would start to cry. " -- Are you busy? Can you come over?"