For Naruto, he would likely gain a new level of understanding about the Uchiha. His view of the Sharingan and the power it holds might change. He could also develop a more nuanced approach to dealing with enemies, as Mikoto might teach him some of the Uchiha's battle strategies.
The plot might involve Mikoto helping Naruto understand the Uchiha clan better. Since she was part of the clan, she could share the history and values of the Uchiha with Naruto. This would not only strengthen Naruto's understanding of his comrades but also give him new perspectives on handling power and loyalty. For example, she could teach him how the Uchiha's Sharingan was related to their emotions and how to use that knowledge in battles.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
In fanfiction, Naruto is often the central character. His relationship with Kushina, his mother, can be explored in depth. For instance, there could be stories about how Kushina passed on her strength and will to Naruto. Mikoto, on the other hand, can be brought into the story to show the connection between the Uzumaki and Uchiha clans. Maybe she helps Naruto understand more about Sasuke's past.
In fanfiction, Naruto, Kushina, and Mikoto can be portrayed in various interesting ways. Some fanfictions might focus on their family relationships. For example, Kushina being Naruto's mother could lead to stories exploring her influence on his growth. Mikoto, as Sasuke's mother, could be part of crossovers where her relationship with Kushina is explored, perhaps in a pre - Konoha setting. It gives writers a chance to expand on the characters' backstories and create new adventures for them.
It might be that mikoto has a vivid imagination and Naruto provides a rich backdrop for her to exercise it through fanfiction. She could be intrigued by the various ninja techniques and powers, and fanfiction allows her to create her own stories involving them. Additionally, she may have become so attached to the Naruto characters that she wants to continue their stories in her own way, adding her own twists and turns to the pre - existing Naruto narrative.
In such a fanfiction, Mikoto would likely be very protective of Naruto. As a godmother, she would probably be involved in his upbringing, teaching him things about the ninja world, and maybe even some Uchiha clan secrets if she thought it was necessary for his growth.
In this fanfiction concept, it could lead to a really interesting dynamic. Jiraiya is a powerful and eccentric ninja. He could teach Naruto some really unique jutsu, like more advanced forms of Rasengan. And their relationship would be filled with Jiraiya's boisterous personality clashing and also complementing Naruto's determination.