Well, it could be that Itachi trains Naruto to better control his chakra. Maybe Itachi sees potential in Naruto to bring peace to the ninja world and decides to pass on his unique skills like the Sharingan's insights on combat.
The plot development could be centered around Itachi's goal to change the future. He sees potential in both Naruto and Sasuke to bring about peace in the ninja world. He starts by training them separately. For Sasuke, he delves into the advanced levels of fire - style jutsu and the sharingan's true potential. With Naruto, he focuses on improving Naruto's speed and reaction time, which are crucial against fast - paced opponents like the Uchiha. As they progress, Itachi then brings them together for joint training. This forces them to learn to work as a team, something that has always been a struggle for them. Their combined skills would then be used to face threats that neither could handle alone.
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.
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.
It could be Orochimaru. Since he's always after power and Naruto, with Itachi's training, would become a more appealing target. Orochimaru might see Naruto as a threat to his plans of obtaining all the jutsu in the ninja world.
One possible plot twist could be that Naruto, despite being trained by Shisui and Itachi, struggles with the darker aspects of their teachings. For example, he might find it hard to adapt to their more stealthy and sometimes morally ambiguous tactics. Another twist could be that an enemy figures out Naruto's new training sources and uses it against him by setting traps based on the Uchiha's fighting styles. Also, Naruto could discover a hidden connection between the Uchiha clan and his own Uzumaki heritage during the training process that changes his perspective on his powers and destiny.
For Naruto, his character growth would be significant. He's always been about friendship and protecting his loved ones. With Itachi as his trainer, he'd learn about sacrifice and the greater good from Itachi's own experiences. This would add a new layer to his beliefs. In terms of power, he'd be able to better control his chakra and develop new jutsu combinations. Sasuke would grow out of his revenge - driven mindset. Itachi's training would show him that there's more to life than just avenging his clan. He'd become more of a team player, especially when training alongside Naruto. And his skills with the Sharingan and other Uchiha abilities would reach new heights.
In this fanfiction, Itachi might also train Naruto in the ways of the Sharingan. Even though Naruto doesn't have the Sharingan naturally, Itachi could find ways to make Naruto understand the principles behind it, like how to read an opponent's movements more accurately. This could lead to Naruto having an edge in battles against opponents who rely on speed and deception.
Well, in this fanfic, perhaps Naruto is sent to the Hidden Mist for some sort of exchange program. There, Mangetsu takes him under his wing. Mangetsu might train Naruto not only in combat skills but also in stealth and strategy. Naruto, with his already strong will and determination, quickly adapts to Mangetsu's teachings and starts to combine his own Uzumaki - like chakra control with the water - style jutsu he learns, becoming a more versatile ninja.
In such a fanfic, perhaps Jango would train Naruto in the art of assassination. Naruto, known for his more straightforward combat, could struggle at first but then adapt these new skills. He might use the stealth aspect of assassination training to better approach his enemies in battle. This would not only change his fighting but also his strategic thinking in missions.
The 'naruto trained by lilith fanfic' might have a plot where Lilith takes Naruto on a journey to different places for his training. These places could be filled with strange creatures or dangerous terrains. During this journey, not only does Naruto learn physical skills from Lilith, but also gains a deeper understanding of the world around him and how to use his chakra in more creative ways. Lilith could also introduce Naruto to new allies or enemies, which would further develop the story.