Well, another aspect could be the origin of how Naruto gets the Rinnegan in this evil scenario. It could be some dark and mysterious force that bestows it upon him. And then, how he explores and masters the powers. He could be using the Preta Path in a really devious way, sucking the chakra out of his opponents not just to defeat them but also to increase his own power in a very unethical way.
One interesting concept could be how Naruto's character changes with the Rinnegan in an evil context. Maybe his views on power and friendship shift drastically. For example, he might use the powers of the Rinnegan to control others instead of protect them.
In some 'naruto black rinnegan fanfiction', there might be a new backstory for how the black rinnegan came to be. It could be related to an ancient and long - forgotten clan in the Naruto universe. This would add a whole new layer of mystery and intrigue to the story.
Some fanfictions might focus on the moral implications of having the Rinnegan. Since it's such a powerful dojutsu, characters with it could face different moral dilemmas. For instance, should they use its powers for domination or for the greater good? And how does the possession of the Rinnegan change a character's personality? Does it make them more power - hungry or more altruistic? These are all things that can be explored in Rinnegan fanfiction.
One interesting concept could be exploring the reasons behind the abandonment of the Rinnegan in the fanfiction. Maybe it's due to some unforeseen consequences or a character's choice that goes against the typical use of the Rinnegan in the Naruto universe.
The idea of new alliances and rivalries can also be explored. With the power of the Eternal Rinnegan, other ninja villages may either seek an alliance or become rivals. Fanfiction could delve into the politics and power dynamics between villages, and how the character with the Eternal Rinnegan navigates these complex relationships.
One interesting concept could be an exploration of Naruto's dark side. It might show how his experiences could have turned him truly evil, like if he had been more influenced by the hatred in the ninja world from the start. Maybe in this fanfiction, he uses his powers for self - gain rather than for the good of the village.
One interesting concept is the combination of powers. In fanfiction, often the Mangekyou Sharingan and Rinnegan abilities are merged in unique ways. For example, a character might be able to use Susanoo with the added space - time manipulation of the Rinnegan. Another concept is the backstories created for how characters obtain these powerful eyes. It could be through some long - lost family heritage or a strange encounter with a powerful entity. Also, the exploration of the psychological effects of having these eyes is fascinating. Characters may struggle with the newfound power and the moral implications that come with it.
One interesting concept could be the exploration of new jutsu combinations. Since the Rinnegan is a very powerful dojutsu, fanfiction might imagine unique ways a character with shared Rinnegan could use its abilities. For example, combining the Rinnegan's power to control gravity with Naruto's shadow clone jutsu in a way that has never been seen before in the original series.
One interesting concept could be the unique powers associated with the red rinnegan. Maybe it has powers that are different from the regular rinnegan in terms of combat abilities, like being able to manipulate a new type of energy or having a special form of genjutsu. Another concept might be how the character who possesses it interacts with other characters in the Naruto universe. They could either be feared or revered, and this would change the power dynamics among different ninja clans.
A concept could be a reincarnation story. A character is the reincarnation of ancient ninja who once mastered all three eyes. They start to have strange dreams and visions related to the powers of the Sharingan, Byakugan and Rinnegan. As they explore these, they gradually unlock the hidden potential within them. This would involve a lot of mystery and self - exploration in the story.
One interesting concept could be the idea of a character in the Naruto universe who is an evil genius and how they manipulate the existing power structures. For example, they might use their intelligence to turn different ninja clans against each other for their own gain.