Naruto's character development in this fanfiction scenario would be multi - faceted. Firstly, his relationship with Itachi would be a major factor. He'd respect Itachi more and perhaps see him as a mentor. As he trains in the Sharingan, he'd learn discipline in a new way, different from his training with Jiraiya. His interactions with other characters, especially those who are wary of the Sharingan's power, would change. He might have to prove that he can use this power for good. His growth would not only be in terms of combat skills but also in his maturity and how he views the ninja world as a whole.
Naruto's character would develop a new sense of self - confidence. Having the Godlike Sharingan and being trained by Itachi would give him a feeling of being a part of something greater. He would no longer be just the 'loud - mouthed underdog' but a powerful ninja with unique abilities. However, he would also have to deal with the new expectations that come with this power. He might struggle with the idea of whether he is still the same Naruto or if the power has changed him too much. This internal conflict would be an important part of his character development as he tries to find a balance between his old self and the new, more powerful version of himself.
His understanding of the Uchiha and the darker side of the ninja world would deepen. Itachi would share his experiences, and Naruto would gain a more nuanced view. This might make him more empathetic towards enemies. Also, his combat skills would diversify. He could incorporate Itachi - like precision and speed into his fighting style, becoming a more well - rounded ninja.
Naruto's character would likely become more serious and focused. Training with Shisui and the Sharingan would demand a lot of concentration, so he'd have to tone down his wilder side. He might also become more strategic in combat, as the Sharingan gives insights into opponents' moves.
Well, in a fanfiction where Naruto is trained by Itachi in Sharingan, Naruto would first have to adapt to the new power. Itachi would probably start with the basics of how to activate and control the Sharingan. Since Naruto is used to his own physical and chakra - based training, this would be a challenge. However, with Itachi's guidance, he could master it. Once he does, he could use the Sharingan to analyze his opponents' fighting styles better. For example, he could quickly figure out the weaknesses in an enemy's jutsu and counter them effectively. He could also use the Sharingan's visual prowess to enhance his reaction time during battles.
One aspect of the plot could be Naruto's struggle to control the new power. The Godlike Sharingan is a powerful and potentially dangerous ability. Naruto might initially have a hard time adjusting to seeing the world through the Sharingan's perspective. Itachi would then have to guide him through this process. Also, they could face enemies who are after the power of the Godlike Sharingan that Naruto now has, leading to intense battles where Naruto has to use his new skills and the knowledge Itachi has imparted to him.
Naruto would likely become more stealthy. Itachi is known for his stealth and if he trains Naruto, Naruto would pick up some of those skills. He might start to rely less on his brash and straightforward fighting style and incorporate more subtlety.
In some fanfictions, it could be through a special jutsu or ritual. Maybe Itachi, before his death, transferred his Sharingan to Naruto in a unique way, perhaps using a forbidden technique that was known only to a few in the Uchiha clan.
One way could be through a powerful jutsu gone wrong. Maybe a jutsu that was meant to transfer Itachi's memories to Naruto accidentally transferred his Sharingan as well. In the world of fanfiction, there are often many creative and out - of - the - box explanations.
One possible plot could be that Itachi, seeing Naruto's potential and his importance for the future of the Hidden Leaf, decides to secretly train him. Itachi might teach Naruto advanced jutsu, especially those related to chakra control and unique Sharingan - inspired techniques. Naruto, under Itachi's tutelage, would grow not only in power but also in his understanding of the ninja world's complex politics and the Uchiha clan's history.
His view of the world would expand. Naruto, who was mainly focused on the ninja world, would now be exposed to the magical world through Merlin. This would make him more open - minded and understanding of different cultures and powers. He may also start to use his newfound knowledge to try and bring peace not just between ninja villages, but also between the ninja world and the magical realm Merlin comes from.