In this fanfiction concept, Naruto and Sasuke as brothers could lead to a very different Naruto universe. With Sasuke having the Sharingan, he could potentially use it to protect Naruto more often. Maybe they would train together in new ways, combining Sasuke's Sharingan - related jutsu with Naruto's Uzumaki power. For example, Sasuke could use his Sharingan to analyze Naruto's chakra flow and help him master new forms of the Rasengan faster.
Yes, in some fanfictions, Naruto might end up having Sasuke's Sharingan through various creative plot devices. For example, in a story where there's a powerful jutsu gone wrong that transfers Sasuke's abilities, including his Sharingan, to Naruto. This can lead to really interesting character developments as Naruto has to learn to control and use this new power.
Naruto might adapt by first trying to understand the basic functions of the Sharingan. He could start with the simple ability to see chakra flow more clearly. Since he has always been perceptive about people's emotions, he could use the Sharingan to read the emotions of his enemies through their chakra, which would help him in battles.
Well, in such a fanfiction, one possibility is that Naruto would inherit some of the Sharingan's powers through their brotherly bond. Since they are so close, Sasuke's Sharingan might react differently to Naruto. It could give Naruto an ability to see chakra in a new way, similar to how the Sharingan works. This would be a really cool addition to Naruto's existing powers and would make their battles more interesting.
One way could be through a kekkei genkai transfer jutsu. If a powerful ninja, perhaps an old hermit with knowledge of ancient jutsus, decides to transfer Sasuke's Sharingan to Naruto for the greater good of the village. This jutsu might be risky but in the world of fanfiction, anything is possible.
A plot development might involve Naruto struggling to control the Rinnegan at first. Sasuke, noticing this, believes he can defeat Naruto easily with his Sharingan. But as Naruto starts to master the Rinnegan, he shows new abilities that shock Sasuke. This could lead to a situation where they have to team up against a common enemy who is after the power of both the Rinnegan and the Sharingan. Or perhaps a prophecy is revealed that states only one of them can keep their dojutsu power and they must fight to decide who keeps it, leading to a moral and power - based struggle.
Well, it might be that there's a powerful enemy who can only be defeated if Naruto has the Sharingan. Sasuke, realizing this, decides to transfer his Sharingan to Naruto. In the fanfiction, Naruto would then have to deal with the new power. He might struggle at first to control it as it's not his natural ability. But as time goes on, he could use it to better understand Sasuke's perspective and strengthen their bond even more. He could also use it in battle, perhaps seeing his opponents' moves more clearly and countering them more effectively.
In a fanfic, Naruto getting Sasuke's Sharingan could be part of a plot where Sasuke sacrifices himself to save Naruto. Before dying, he gives Naruto his Sharingan. Naruto then has to deal with the new power as well as the emotional weight of carrying a part of Sasuke. He could use the Sharingan to see through illusions more easily and even gain some of Sasuke's memories related to the Sharingan's usage.
One great fanfiction could be about Naruto and Sasuke growing up as brothers and discovering the power of the Sharingan together. They might face challenges like protecting their village from a new and powerful enemy. The Sharingan could give them an edge in battle, and their brotherly bond could be a source of strength for both of them.
One common theme is the power struggle. Since the Sharingan is a very powerful ability, many fanfictions explore how Naruto and Sasuke deal with the power that comes with it. For example, they might struggle with the temptation to misuse it or have to learn to control it.