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.
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.
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.
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.
The fanfic could be centered around Sasuke's best friends, Naruto and Sakura, and how they interact with Sasuke's Sharingan. For instance, Naruto might be curious about the Sharingan's abilities and constantly ask Sasuke to show him new tricks. Sakura, being a medical ninja, could study the Sharingan's effects on Sasuke's body to ensure he doesn't overuse it and harm himself.
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.
Yes, there are many. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Naruto Eternal Sharingan Sasuke' and you'll find a bunch of them, but the quality may vary.
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.
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.
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.