There could be a 'naruto kills jiraiya fanfiction'. It could be based on a time - travel scenario. For example, if Naruto from the future travels back in time and somehow his actions cause a chain of events that lead to Jiraiya's death. Or perhaps there's a dark, alternate universe where Naruto's values are twisted and he sees Jiraiya as an obstacle to his new, malevolent goals and thus kills him.
Sure, such a fanfiction could exist. Maybe in the story, there's a powerful and ancient curse that gets placed on Naruto. This curse slowly corrupts his mind and makes him turn on those closest to him. Jiraiya, being one of his closest mentors, tries to save him but Naruto, in his cursed state, is too strong and ends up killing Jiraiya.
Perhaps in this fanfiction, Jiraiya discovers that Naruto is going to be the cause of a major catastrophe in the future. He might have seen a prophecy or some sort of sign that convinces him Naruto has to die to prevent this. It could also be that Jiraiya has been misled by false information about Naruto, which makes him think that Naruto has become an evil force that needs to be eliminated.
Well, if there is a 'naruto kills kakashi fanfiction', it would be a very different take on the Naruto universe. It could be set in a world where Naruto has been corrupted by an evil force. This force could be manipulating Naruto's emotions and memories, making him think Kakashi is a threat. In the original series, they have a strong bond, so this would be a very controversial and unexpected plot.
There might be a very dark and twisted fanfiction like that. It could be that Naruto is tricked into believing that Minato and Kushina are some kind of threat to the village or to his friends. So in a moment of confusion and misinformation, he takes drastic action. But this goes completely against Naruto's character in the original series.
Yes, there might be such fanfictions. One possible plotline could be that Kami has been corrupted in some way and Naruto, in his sense of justice, has to take extreme measures. Maybe Kami starts to harm the village or its people, and Naruto, as the protector, has no other choice but to fight and end Kami's existence. Another could be that Naruto is tricked into believing Kami is a threat when in fact it's a misunderstanding created by an enemy.
One possible plotline could be a case of extreme misinformation. Maybe Naruto is tricked into believing that Raikage is about to launch a devastating attack on Konoha. So, in a moment of panic and believing he is protecting his village, he kills Raikage. Another could be a dark influence. For example, if Naruto is somehow possessed by a malevolent force that drives him to kill Raikage against his will.
One possible plotline could be that Naruto is somehow mind - controlled. Maybe an enemy uses a powerful genjutsu on him, making him see the Konoha 12 as threats to the village instead of comrades. This would lead to a tragic situation where Naruto, in his altered state of mind, attacks them.
One possible plotline could be that Naruto has to kill Momoshiki to protect the Hidden Leaf Village. Maybe Momoshiki has some new and extremely dangerous power that threatens the safety of the village and its people. Naruto, being the hero, steps up and in a fierce battle, manages to defeat and kill Momoshiki.
One possible plotline could be Naruto feeling extremely lost and having to find his own way to become stronger without their guidance. He might start to question his own worth and abilities, but then he could meet new allies who help him realize his true potential on his own. For example, he could encounter some other outcast ninja who have their own unique skills and together they form a new kind of ninja team that challenges the traditional ways of the ninja world.
One possible reason could be mind control. Some dark power might take over Naruto's mind and force him to turn on Jiraiya without his own will.
One possible reason could be that Naruto feels he has learned all he can from Jiraiya at that point. Maybe he has reached a level in his training where he believes he needs new experiences and challenges that Jiraiya can no longer provide.