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.
In some Naruto fanfictions, Jiraiya's death might be different from the original. One common way is that he might have had more backup during his fight with Pain. Maybe some new characters created in the fanfiction came to his aid at the last moment, preventing his death. However, in other fanfictions, his death could be even more tragic, like being betrayed by someone he trusted before facing Pain, which weakened him and led to his ultimate demise at the hands of Pain.
In some fanfictions, Jiraiya might save Naruto by teaching him powerful new jutsus. For example, he could pass on some secret toad - related techniques that Naruto uses to defeat a powerful enemy.
Maybe in some fanfictions, the writer wants to create a new plot where Naruto has some misunderstandings about Jiraiya. For example, if Jiraiya made a decision that Naruto thought was wrong regarding the village or his friends, it could lead to Naruto hating him in that fictional scenario.
Maybe he hates it because it often distorts the original story. Fanfictions might take his character or Naruto's in directions that he wouldn't approve of in the original Naruto universe.
She could physically harm him. Maybe in a fit of anger, she punches or uses her strength on Jiraiya. Since Tsunade is known for her powerful physical attacks, it would be a likely way for her to hurt him. Another way is through emotional harm. She could reject Jiraiya's feelings for her in a very cruel way, saying things that cut deep into his self - esteem and his love for her.
It can create a sense of growth for Naruto. Without Jiraiya by his side, he has to rely more on his own instincts and the skills he has already acquired. This can lead to new character development as he faces challenges alone.
The training makes Naruto more confident in his abilities. Jiraiya constantly challenges Naruto and as Naruto overcomes these challenges, he realizes his own strength. He starts to believe in himself more, which is evident in the way he faces stronger opponents without hesitation later on. Also, Jiraiya's teachings about the ninja way and the importance of protecting those you love make Naruto more determined and focused on his goals.