In terms of his power level, it could be slower to increase. Jiraiya's training was crucial in Naruto's growth in the original story. Without it, Naruto may not be as strong as quickly. However, this could also lead to him finding alternative ways to become powerful, like forming different alliances or exploring unorthodox ninja paths.
Naruto might develop different skills. Without Jiraiya's training, he could focus more on self - taught techniques or learn from other characters. For example, he might learn more about the Uzumaki clan's unique abilities from someone else in the village.
Well, in the original story, Jiraiya played a big role in Naruto's emotional growth too. If he doesn't train Naruto in the fanfiction, Naruto might lack the father - figure like guidance that Jiraiya provided. This could lead to Naruto making different decisions in life, both in terms of his relationships and his ninja career. For example, he might not have the same understanding of the ninja world's politics and power struggles, which could put him at a disadvantage. Also, his connection to the Sage Mode might be completely different or non - existent, which would change how he fares in battles against powerful enemies.
One possible reason could be that in this fanfiction, Jiraiya might be preoccupied with other important matters. Maybe he has a secret mission that demands his full attention and he simply doesn't have the time to train Naruto. Another reason could be that there is some sort of conflict or misunderstanding between them that prevents Jiraiya from taking Naruto under his wing. For example, Naruto might have unknowingly offended Jiraiya in some way, or there could be a prophecy or external force that is keeping them apart for the time being.
Perhaps Jiraiya has some personal issues or inner conflicts. He might be dealing with his own past traumas or demons that prevent him from taking on the role of Naruto's trainer. For example, he could be haunted by the failures in his previous relationships or battles, and he feels unfit to train Naruto until he sorts out his own problems.
Jiraiya could also train Naruto seriously in fanfiction through intense physical conditioning. He might make Naruto run long distances, climb mountains, or swim across large bodies of water. This would build Naruto's stamina and strength, which are crucial in battle. Additionally, Jiraiya could teach Naruto advanced ninjutsu techniques, like new ways to use his Rasengan or how to combine different elemental jutsus.
It would likely accelerate his growth. Jiraiya is a very experienced ninja. With his guidance, Naruto would gain more confidence. For example, if Jiraiya found Naruto early on, he could teach Naruto better control of his chakra, which was a struggle for Naruto in the beginning. This would make Naruto more efficient in battles and less reliant on brute force.
Naruto might be initially very disappointed. He has always looked up to Jiraiya and expected to be trained by him. So, when faced with the refusal, he could be heartbroken and feel like he has lost a great opportunity.
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.
His relationships with others would also change. For instance, his bond with Sasuke might not be as intense in terms of power rivalry. Since he doesn't have the Kyuubi, Sasuke may not see him as a threat in the same way. Naruto would probably have to work harder to prove himself worthy to his friends and the village. He'd be more of an underdog in a different sense, relying solely on his own efforts and natural talents rather than the Kyuubi's power, which would lead to a more humble and determined Naruto.
Jiraiya's training in the fanfiction might focus on Naruto's inner strength as well. He could help Naruto better understand and control the Nine - Tails' power. This new - found control would give Naruto a sense of calm and authority. His character would shift from being just a loud - mouthed underdog to a more respected and powerful ninja. Naruto would also learn about loyalty and sacrifice from Jiraiya, which would shape his values.
Naruto becomes more determined. With Jiraiya's death, he realizes that he has to grow up faster and become stronger. So, his focus on training intensifies, and he's more eager to master new techniques.