In a fanfic, Naruto with the Rinnegan and Sharingan would have a whole new set of challenges. He would have to deal with the jealousy and fear of other ninja villages. His own village might also be divided on how to handle his new powers. On the positive side, he could use these eyes to better understand the history of the ninja world. For example, the Rinnegan might give him insights into the Sage of Six Paths' true intentions, and the Sharingan could help him uncover secrets about his own family. He would also have to train hard to fully utilize the combined potential of these two powerful eyes, which could lead to some interesting training arcs in the fanfic.
Well, if a Young Justice character had the Sharingan, it could open up new storylines. They could use it to discover secrets about their own world or other characters. For instance, if Superboy got the Sharingan, he could use it to look deeper into his own origin and the secrets that Lex Luthor or the Cadmus Project might be hiding. This would not only affect his character arc but also the overall plot of the fanfiction as he uncovers things that could change the fate of the Young Justice team.
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.
It could have completely changed the dynamics of his battles and his relationships with others. The Sharingan would have given him an extra edge and new abilities.
Well, if Naruto gets Shisui's Sharingan in a fanfiction, he could gain some really cool abilities. The Sharingan has powers like enhanced perception and the ability to copy jutsu. Naruto already has his own powerful chakra and skills, so with the Sharingan, he might become an even more formidable ninja. He could potentially use the Sharingan's genjutsu capabilities to his advantage in battles, maybe even use it to break through tough enemy defenses more easily.
They could go on a journey to find a way to heal any negative effects of the Sharingan on Sasuke. Naruto would be by his side every step of the way, providing emotional support. As they travel, they face various challenges, and Sasuke uses his Sharingan to analyze the situation while Naruto uses his brute strength. Their combined efforts make them an unbeatable team.
He would probably become an even more formidable fighter. The Blades of Chaos could add a new dimension to his combat style, allowing him to perform more acrobatic and powerful attacks.
Well, it could be really chaotic. Naruto already has a powerful force within him with the Nine - Tails. If Sans was sealed in him too, Naruto might gain Sans' unique abilities like his teleportation and bone attacks. His fighting style would become extremely unpredictable, mixing ninja techniques with Sans' skeletal powers.
He would probably become extremely powerful. The Super Soldier Serum is known for enhancing physical abilities. Naruto already has his chakra powers. With the serum, his strength, speed, and endurance would likely skyrocket. He might be able to take on much stronger opponents in the DxD universe with ease.