The other villages might react with a mix of shock and suspicion. They knew Naruto was a powerful force for good in the ninja world. His death could be seen as a sign that something was amiss in Konoha. Some villages might even fear that Konoha was becoming unstable and could pose a threat. Characters like Gaara, who had a special bond with Naruto, would be deeply saddened and might try to find out the real reason behind Naruto's death.
One possible plot could be a dark turn in the story. Maybe Kakashi is under some kind of mind - control. He could be forced to fight Naruto by a powerful enemy who has taken over his mind. Naruto, being unprepared for such an attack from his mentor, gets killed. This would then lead to a series of events like Sasuke going on a rampage to find out the truth and avenge Naruto, and the whole ninja world being in shock as one of their most promising heroes is gone.
Yes, there might be such fanfictions out there in the vast world of fan - created content. However, this goes against the general storyline of the Naruto series where they are comrades.
In some fanfictions, it could be due to a special jutsu gone wrong. Maybe a jutsu that Kakashi was using to transfer some of his chakra to Naruto for a mission accidentally transferred his Sharingan power as well.
If Naruto was raised by Kakashi in fanfiction, their relationship would be very different from the original. Kakashi could teach Naruto more about the Sharingan and its secrets since he has one. Naruto might also inherit some of Kakashi's reading habits and love for Icha - Icha Paradise, which could lead to some really funny moments.
I'm not aware of any such fanfic. Naruto is a male character in the series, and such a concept goes against the natural order of the Naruto universe. Fanfics usually follow the general theme and characteristics of the original work, and this seems quite out of place.
Often, in 'naruto gets trained by kakashi fanfiction', Naruto will face various challenges during the training. These challenges could be physical, like enduring intense sparring sessions with Kakashi. Or they could be mental, such as understanding complex ninja concepts. Through these experiences, Naruto not only becomes more powerful but also gains a deeper understanding of himself and his ninja path. This might also lead to him forging a stronger bond with Kakashi, which could play a significant role in future plot developments.
In some fanfictions, when Kakashi finds Naruto, it could be a situation where Naruto is in danger. Kakashi would then rescue him and from that moment on, their bond becomes even stronger. Kakashi might then focus on helping Naruto control the Nine - Tails' chakra more effectively, which would change the course of Naruto's development in the story.
Another situation is when Kakashi is on a solo mission. He might encounter a group of powerful opponents who manage to wound him. This forces him to rely on his wits and basic ninja skills to survive while waiting for backup. It can show his resourcefulness even when injured.
It's a rather unique concept. In the original Naruto series, Kakashi is a mentor figure to Naruto. The idea of Kakashi killing Naruto goes against the general bond and narrative. So in fanfiction, it's not a common theme as most fanfics tend to follow the positive relationships from the original. However, it can attract those who like exploring dark or alternative storylines.