One interesting plotline could be Kakashi struggling to control the new power. Since the Rinnegan is extremely powerful, he might initially have a hard time adjusting. For instance, he accidentally activates its powers during a simple sparring session and causes a huge commotion. Another plotline could be how the other ninja react to Kakashi having the Rinnegan. Some might be jealous, some might be afraid, and some might see it as a new hope for the village.
Well, one way could be related to Orochimaru's experiments. Orochimaru is always into playing with genetic material and powers. He might have found a way to implant the Rinnegan - related genes into Kakashi, accidentally or on purpose. Another possibility is that in a different timeline or dimension, Kakashi is chosen by some divine force to receive the Rinnegan to fight against an ultimate evil that threatens all the ninja villages.
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.
In many fanfictions, the Rinnegan and chakra chains are often intertwined in terms of power and function. The Rinnegan, being one of the most powerful ocular abilities in the Naruto universe, can potentially bestow special properties on the chakra chains. The chakra chains themselves might be a way to channel the raw power of the Rinnegan. For instance, they could be used to bind opponents while simultaneously draining their chakra through the Rinnegan's absorptive capabilities. This connection adds an interesting dynamic to the characters who possess both the Rinnegan and the ability to use chakra chains, making for some really cool and unique battle scenarios in fanfiction.
Well, perhaps the protagonist uses the powers of the Rinnegan in secret. He might train alone and develop unique abilities that others are unaware of, so that when the time is right, he can surprise everyone who has neglected him.
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 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.
Often, Gai is paired with Kakashi in Hurt Kakashi fanfiction. Gai, with his unwavering belief in friendship and his eternal rivalry with Kakashi, can be a great character to interact with a hurt Kakashi. He might try to pull Kakashi out of his slump through their friendly competition. Also, Rin is sometimes included. Since she has a significant past with Kakashi, her presence in the fanfiction can either be a source of comfort or more pain, depending on how the story is written.
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.