One way to incorporate Naruto's Rinne Sharingan in a Highschool DxD fanfiction could be through a crossover event. Maybe a character from the Naruto universe accidentally ends up in the Highschool DxD world and has the Rinne Sharingan. Their unique powers could disrupt the balance in the new world, leading to various interesting plot developments. For example, they could use the Rinne Sharingan's abilities to see through illusions in the Highschool DxD world which is full of magic and deception.
One way could be through a crossover character. Imagine a character from Naruto's world ending up in the Highschool DxD universe with their Sharingan. They could use it in battles against the devils and fallen angels in the Highschool DxD world. For example, the Sharingan's ability to predict movements would give them an edge in combat.
In a Sharingan Naruto Highschool DxD fanfiction, the Sharingan could also play a role in terms of illusions. Imagine a scenario where the character uses Sharingan - based illusions to deceive the enemies from both worlds. They could make a Highschool DxD devil believe they are in a completely different environment like a dangerous Naruto - style forest filled with traps. And for Naruto characters, they could be made to see illusions of their worst nightmares or false threats from the Highschool DxD world, which would make for some really intense and engaging storylines.
One plot idea could be a character from Naruto ending up in the Highschool DxD world and having the Rinne Sharingan. They could use its powers in the battles against the devils and fallen angels in the new world.
You can try fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a large collection of fanfictions related to various anime and manga, including those that combine elements from Naruto, Highschool DxD and the Rinne Sharingan concept.
If a Highschool DxD character got the Rinne Sharingan, they would gain a whole new set of abilities. They could potentially use the Rinnegan's ability to see chakra to detect the magic energy in their own world in a different way. For example, they might be able to see the flow of magic within spells and use that knowledge to counter them. Their combat abilities would also increase significantly as they could use the various powers associated with the Rinne Sharingan like the ability to summon creatures or use powerful elemental attacks.
The stray devil could be a plot device to bring out new character developments. For example, in Naruto's world, the characters are used to dealing with their own types of threats like the Akatsuki. But a stray devil has different powers and motives. Similarly, in Highschool DxD, the devils, angels, and fallen angels have their own power dynamics. The stray devil's appearance could force characters from both sides to re - evaluate their alliances and strategies.
Well, it depends on the specific fanfiction. There are countless Naruto fanfictions out there. Some authors might decide to give Naruto the Rinne Sharingan to make him even more powerful or to introduce new plot twists. For example, it could be a result of some special training or a mysterious power transfer in the fictional world of the fanfic.
In a Highschool DxD OC and Sharingan fanfiction, you can incorporate the Sharingan powers in the story by making it a source of mystery and envy among the other characters. The OC could use the Sharingan's ability to enter the minds of others (a more advanced form) to gather information about the devils' plans. This would make the OC a valuable asset to their group. Also, the Sharingan could have a connection to some ancient prophecy in the Highschool DxD world, which would add more depth to the story and make the powers more significant in the overall plot.
It can also change Naruto's relationships. His friends might be in awe or even a bit scared of his new power. Enemies would surely target him more. Also, it could mean new story arcs. For example, he might have to deal with the dark side of the Rinne Sharingan's power, like being tempted by its overwhelming abilities. And he may need to find a way to use it for good without succumbing to its potential negative influences.
A possible fanfiction could be about the origin of the Rinne Sharingan having some connection to the world of RWBY. Maybe there was an ancient civilization in RWBY's past that had a similar power, and through some sort of dimensional rift, it influenced the development of the Rinne Sharingan in Naruto's world. This would involve a lot of world - building and exploration of both universes' histories.