Naruto's perspective on the ninja world could change. With the Rinnegan, he would see things in a different light, both literally and metaphorically. He might have to deal with new enemies who are attracted to his new power or new responsibilities that come with such a powerful dojutsu. His relationships with his friends and allies could also be affected as they may view him differently now that he has this extremely powerful ability.
In this kind of fanfiction, the author might come up with a convoluted plot. For example, Itachi could have discovered an ancient technique that allows him to bestow the Rinnegan on Naruto. It might involve sacrificing his own ocular powers in a way that defies the normal rules of the Naruto universe. This would be a very creative and out - of - the - box idea, but that's the beauty of fanfiction.
In some fanfictions, it could be through a strange and powerful jutsu transfer. Maybe Madara, on the verge of defeat, decides to transfer his Rinnegan power to Naruto for some unforeseen reason, like seeing a new path for the ninja world in Naruto.
In some fanfiction concepts, the chakra of the Kyuubi is not just pure fox chakra but also contains remnants of the Sage of Six Paths' power. Since the Rinnegan is related to the Sage of Six Paths, when Naruto reaches a certain level of power and harmony with the Kyuubi, the dormant Rinnegan - like power within the Kyuubi's chakra awakens in Naruto. This could be a result of Naruto's strong will and his journey to master the Kyuubi's power which eventually leads to him obtaining the Rinnegan.
The plot could take a turn where Naruto is hunted by those who want the Rinnegan for themselves. Orochimaru might be very interested in Naruto's new power. Also, other villages might see Naruto as a threat. This would force Naruto to either hide his power or use it to assert his dominance. It could also change his relationship with Sasuke, as Sasuke has his own power goals, and Naruto's Rinnegan might either make Sasuke more competitive or more willing to team up with Naruto.
Well, if Naruto got the Rinnegan as a kid in fanfiction, it might make him a target for various enemies and force him to grow up faster. Also, it could completely rewrite his relationships with other characters.
Well, Naruto getting the Rinnegan and joining Akatsuki is a wild concept. It would lead to some really interesting battles. For example, a fight between him and Sasuke would be on a whole new level. Since Naruto has the Rinnegan now, he might have new jutsu and abilities that Sasuke wouldn't be expecting. In Akatsuki, he could also learn a lot about the darker side of the ninja world that he didn't know before. But this would also put him at odds with Kakashi and other Konoha ninjas who have always trusted him. And who knows, maybe he could end up reforming Akatsuki into something good instead of a group of villains.
He could perform powerful genjutsu with the Sharingan. Naruto, who was not really known for genjutsu before, would now be able to create illusions that are difficult to break. With the Rinnegan, he might be able to use the Six Paths techniques, like the ability to control gravity or absorb chakra attacks.
He could develop the ability to use the Six Paths Sage Mode more effectively. Since the Rinnegan is related to the Sage of Six Paths, it would enhance his connection to that power. He might also gain the ability to create chakra chains similar to those of the Uzumaki clan but with an added Rinnegan - powered twist.
One implication is that he becomes much more powerful. The Rinnegan gives him access to powerful abilities like the Six Paths techniques, which would change the power dynamics in battles in the fanfiction. He could now face stronger enemies more easily.