It could also be related to a prophecy or a pre - determined fate in the fanfic's plot. There might be some kind of dark prophecy that says Kawaki has to kill Naruto to prevent a greater evil. Or perhaps Kawaki is being controlled by an external force that has a vendetta against Naruto and uses Kawaki as a tool to carry out the murder.
In such a fanfiction, perhaps Kawaki is driven by some extreme ideology. Maybe he believes Naruto's way of peace is a weakness and decides to take him out to change the ninja world in a more radical way.
No, Kawaki doesn't kill Naruto in the manga. The storyline doesn't go in that direction.
In a 'kawaki kills naruto' fanfic, the story would likely take a very dark turn. The characters would be forced to reevaluate their relationships and loyalties. Sasuke, for example, would be deeply affected as Naruto was his closest friend. He might be torn between seeking revenge and trying to understand what drove Kawaki to such an act. The new generation of ninja, like Sarada and Mitsuki, would also be involved in the aftermath. They might be caught in the middle of the conflict between Boruto and Kawaki, trying to find a way to restore peace while dealing with their own feelings of loss and confusion.
One great 'kawaki naruto fanfic' could be one where Kawaki has to learn a new jutsu from Naruto. In many fanfics, Kawaki is often portrayed as a complex character trying to fit into the Hidden Leaf Village. He might struggle with his past and Naruto could be the one to guide him through it.
Many of Naruto's friends and allies would be filled with rage. Characters like Sasuke would probably seek immediate revenge on Kawaki. The other villages might also see this as a sign of instability in the Hidden Leaf and could either try to take advantage or offer help depending on their relationships with the Leaf. And the younger generation, like Boruto, would be deeply affected. He would have to deal with the loss of his father and might struggle with his own identity and purpose in a world without Naruto.
It could be that Yagura had some secret plans that would endanger the balance among the ninja villages. Naruto, having a strong sense of protecting peace, discovers these plans and decides that eliminating Yagura is necessary. For example, if Yagura was planning to use a powerful and dangerous jutsu that could destroy multiple villages, Naruto would act to prevent it even if it means killing him.
In the 'boruto kills naruto fanfiction', a motive could be a power struggle. Boruto might believe that Naruto's power is holding back the village's growth or his own potential. He could think that by eliminating Naruto, he can bring about a new era of power in the Hidden Leaf. Also, it could be out of desperation. If Boruto is in a situation where he believes that killing Naruto is the only way to save someone he loves, like his mother or a friend, he might take such a drastic step.
One possible motive could be a misunderstanding. Maybe Hiashi mistakes Naruto for an enemy who has infiltrated the village in disguise. Another reason could be related to clan politics. If Naruto somehow gets involved in a situation that threatens Hiashi's clan interests, Hiashi might take extreme measures.
One possible motive could be that Kakuza has committed some heinous crimes against the Hidden Leaf Village. Maybe he has been involved in secret attacks on the village or has been plotting something really bad that would endanger the lives of many villagers. Naruto, being the protector of the village, would then take it upon himself to stop Kakuza by any means necessary, which unfortunately might end up in killing him.
Another place could be some Naruto - focused forums. There are often sections where fans share their own written fanfics. You might need to register on these forums, but it can be a great way to discover unique 'kawaki naruto fanfic' that may not be on the more well - known platforms.