The Sage of Six Paths himself could be the key character. Since the Rinnegan was originally his power, he could appear in the fanfic in some form, like a spirit or a time - traveling version of himself. He could then directly bestow the Rinnegan upon Naruto, seeing Naruto's potential and the need for such power to maintain the balance in the ninja world.
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.
It might be related to a connection with some powerful entity in the Wave arc. For example, if there's a secret shinobi from the past whose power is tied to the Rinnegan and Naruto somehow forms a bond with that power source, it could lead to the awakening. Also, the intense emotions and challenges he faces in the Wave arc might be a catalyst, pushing his chakra to a new level and awakening the Rinnegan.
The Sharingan and Rinnegan are iconic in Naruto fanfic. The Sharingan's different levels, from one - tomoe to three - tomoe and then the Mangekyou Sharingan, offer a wide range of creative possibilities. Fanfic writers might explore the emotional toll of using the Mangekyou Sharingan, like Itachi did. Regarding the Rinnegan, it's often associated with the Sage of Six Paths. In fanfic, it could be used to bring back ancient powers or create new forms of ninjutsu. These two eye - powers can be combined in fanfic in ways that the original series might not have fully explored, making for exciting reading.
In a Rinnegan Naruto The Originals fanfiction, the story could focus on Naruto exploring the true origins of the Rinnegan. He might discover that the Rinnegan has a connection to his Uzumaki heritage that was previously unknown. This could lead to a whole new arc where he has to travel to different hidden villages or ancient ruins to uncover more about this powerful eye technique and how it relates to his family's past.
Well, there's a fanfic called 'Naruto's Rinnegan Adventure'. In this story, Naruto discovers the Rinnegan early on and has to deal with the consequences. It's interesting as it shows how his relationships with his friends and the village change due to this new power. Also, 'Rinnegan - Naruto's New Path' is a good one. It follows Naruto as he uses the Rinnegan to reshape the ninja world, facing many challenges along the way.
It could completely change the power dynamic in the story. Naruto with the Rinnegan would likely become almost invincible, making his battles much less challenging.
Regarding the characters who possess the Rinnegan in the original and the fanfic, there are differences. In the original, we mainly see characters like Nagato and Sasuke with the Rinnegan. In the fanfic, new characters might be introduced with the perfect Rinnegan. These characters could have different relationships with other Naruto characters and different goals, which can significantly change the overall narrative compared to the original story.