Mikoto could be developed as a more powerful figure. Since she has the Sharingan, she could be shown exploring and mastering abilities that were not fully explored in the original series. For example, she might discover a new type of genjutsu unique to her Sharingan that she then uses to protect the Uchiha clan.
In this fanfiction, Mikoto could be developed as a rebel. Tired of the Uchiha clan's traditional ways and the secrecy around the Sharingan, she could break away. With Naruto's influence, she could start to share the secrets of the Sharingan with other clans, believing that only by doing so can they truly achieve peace in the ninja world. This would be a major departure from her more traditional role in the original story.
He might be more reserved. Since Mikoto was known for her grace and elegance, Naruto could adopt some of those traits. He may not be as loud or brash as in the original series.
Mikoto could influence Naruto's understanding of the Sharingan by sharing her own experiences with it. As an Uchiha, she has first - hand knowledge of the power and the curse that comes with it. She could tell Naruto about the different levels of the Sharingan and how to unlock them. This would give Naruto a new perspective on the power and how to use it effectively.
Naruto might become more stealthy and calculating. Mikoto, being an Uchiha, could teach him the art of patience and precision in combat, which would be a contrast to his usual brash and head - on fighting style.
Naruto's character would likely become more confident. With a family structure provided by Mikoto, he would feel more secure. He might also become more mature as he is exposed to the Uchiha way of life. For example, he could learn discipline and patience more quickly. His understanding of the ninja world would expand as he learns from Mikoto about different clans and their relationships.
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.
He would gain new visual abilities. Naruto could now use the Sharingan's powers like predicting movements, copying jutsus more easily. But it might also come with some drawbacks. For example, the Sharingan consumes a lot of chakra, so Naruto would have to manage his energy better.
Naruto's character would likely develop a stronger sense of family. Since Mikoto is known for her loving nature, Naruto would feel more secure. He could also become more attuned to the Uchiha clan's values, which might add a new layer of complexity to his personality. He may be more empathetic towards Sasuke's situation from the very beginning, given his new family connection to the Uchiha.
One way this could occur in the fanfiction is if there was some sort of genetic manipulation. Maybe a rogue ninja or a mad scientist found a way to combine Uchiha genes with Naruto's. Mikoto, being an Uchiha, had the Sharingan, and through this unethical genetic process, Naruto ended up with the Sharingan. This would also open up a whole new set of abilities and challenges for Naruto as he has to learn to control this new power which is very different from his normal chakra - based powers.
He'd be more in - touch with his Uchiha side. So, he might be more brooding at times. His appearance could also be different, maybe having more Uchiha - like features. His approach to problems would likely change too. Instead of just charging in head - first all the time, he might be more calculating like the Uchiha are known to be.
Well, it could be that Mikoto is trapped in a dangerous situation like a collapsing building or a genjutsu. Naruto, with his strong will and powerful chakra, breaks the genjutsu or rescues her from the rubble. He might sense her distress using his Sage Mode or his connection to the Nine - Tails' chakra and rush to her aid.