Sasuke would probably be in denial at first. He has always seen Naruto as a rival and a strong force. But once he accepted the reality, he would do whatever it takes to help, maybe even going on dangerous missions to find a cure. He would also feel a sense of guilt if he had ever underestimated Naruto because of the disease.
Well, in some Naruto fanfictions, a disease could be used to create a really unique plot. For instance, if a disease was created that specifically targeted the Kekkei Genkai holders. It would force the different clans to work together to find a cure. This would be a huge shift from the usual clan rivalries. Maybe the disease was created by a rogue ninja who wanted to wipe out all those with special bloodlines to gain power for himself.
Naruto would likely experience a range of emotions. He could be in denial at first, not wanting to believe that this disease could end his life. Then there would be sadness, thinking about all the things he might not be able to achieve. He'd also feel guilty for making his friends worry. And there would be moments of anger, directed at the unfairness of getting such a disease.
In this fanfiction scenario, Naruto having Itachi's disease could lead to some really interesting character development. He might become more withdrawn like Itachi was, but his friends would surely try to pull him out of it. The story could explore how the disease affects his relationships, not just with his friends, but also with the village. It could also be a chance for him to understand Itachi better on a personal level.
One possible disease could be a mysterious chakra - related illness. It might limit Naruto's ability to use his jutsu effectively. For example, it could cause his chakra to be unstable, leading to failed attacks or even endangering his friends during battles.
In a Naruto bloodline and disease - related fanfiction, the story might revolve around a hidden bloodline trait that is considered a 'disease' by the ninja villages. Say, a bloodline that gives uncontrollable power surges but at the cost of the user's health. A group of outcast ninja with this bloodline could be on a journey to prove that they are not a threat but rather an asset, all while trying to find a way to control this so - called disease within them.
It could strain his relationship with Hinata. She would be worried sick about him and might try to get him to rest more, which Naruto, being stubborn, might resist. This could lead to some arguments between them.
Well, having a heart disease would likely make Naruto more cautious. He might not be as impulsive in battles or training, as he has to think about his health. This could lead to him developing more strategic thinking rather than relying solely on his brute strength.
Well, it would surely slow him down. He might not be able to take on as many dangerous missions. His physical strength could be diminished, and he'd have to rely more on his strategic thinking. Also, his friends would probably be overly protective, which could create some tensions within the team.
His ninja career would be severely affected. His speed and reaction time might decrease due to the physical toll of the disease. He may not be able to take on as many high - level missions.