One of the most heart - wrenching moments in Naruto is Jiraiya's death. In fanfiction, this event is often explored in different ways. Some fanfictions might focus on Naruto's immediate reaction, delving deep into his grief and how it changes his character. For example, there could be a story where Naruto becomes more withdrawn at first, shutting out his friends as he struggles to come to terms with the loss of his mentor.
In some fanfictions, Naruto is completely devastated. He might go into a state of shock at first, unable to believe the news. Then he could be filled with intense grief and anger, blaming himself for not being there to protect Jiraiya.
Jiraiya might comfort Naruto by sharing his own experiences. He could tell Naruto about the times he faced difficulties and how he overcame them. For example, he might talk about his training with the toads and how he grew stronger through perseverance.
One possible reason could be that Naruto feels he has learned all he can from Jiraiya at that point. Maybe he wants to explore his own path independently and test his skills without Jiraiya's constant guidance.
Naruto might also isolate himself in certain fanfic scenarios. He feels that no one can truly understand the depth of his grief. He spends time alone, reflecting on all the things Jiraiya taught him and the memories they shared, like their time training on that toad -infested island.
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.
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.