When Naruto has the Sans eye in fanfiction, it would really shake up his relationships. His closest friends like Sasuke would initially be skeptical. They might think it's a dangerous power that could corrupt Naruto. But Naruto, being Naruto, would try to prove that he can use it for good. His relationship with the village elders would also be different. They might see him as more of a threat or an unknown variable. However, the younger generation of ninjas would likely look up to him even more, seeing him as even more powerful and unique. This could create some jealousy among some of his peers, but also admiration from others.
His relationships could change quite a bit. His friends might be a bit intimidated at first. For example, Sakura might be worried about this new, unknown power. But over time, they would probably come to accept it. His enemies, on the other hand, would be more cautious around him.
This would have a major impact on his relationships. Naruto's new Sans eye power could make some of his friends feel left out or less important. However, true friends like Shikamaru would see it as an asset and try to help Naruto use it effectively. His relationship with his sensei, like Kakashi, would also change as Kakashi would need to help Naruto understand and control this new power.
With Kakashi, Naruto having the Rinnegan could change their teacher - student dynamic. Kakashi would be both amazed and a bit worried. He would need to guide Naruto in a new way, as the Rinnegan brings a whole new set of powers and potential dangers. Naruto might start to teach Kakashi some things he discovers about the Rinnegan, reversing their roles to some extent.
His relationship with Kakashi would also be affected. Kakashi would have to mentor Naruto in a different way. He would need to teach Naruto how to use the Byakugan effectively, which is different from what he's used to with Naruto's normal abilities. This could strengthen their bond as teacher - student, or it could create some friction if Naruto struggles to adapt to Kakashi's new teaching methods.
In terms of his romantic relationships, if there were any potential love interests, they might be more hesitant. However, Naruto's determination and positive attitude could still win them over. His relationships with his teammates from Team 7 would likely shift. They would need to adjust their battle strategies to account for his one - eyed state. His bond with Hinata could also be tested as she might worry more about his safety and his ability to protect himself and the village.
Naruto's relationship with his teachers could be different too. Kakashi, for example, would need to adjust his training methods for Naruto. He would have to help Naruto master the Byakugan while still maintaining his existing skills. And Naruto might also have new interactions with other powerful ninjas in the village or from other villages, as they are curious or intimidated by his new - found Byakugan - related abilities.
If Naruto had a powerful quirk, his relationship with Sasuke might be more competitive. Sasuke is always striving to be stronger, and if Naruto suddenly had an extremely powerful quirk, Sasuke would be even more determined to catch up or surpass him.
With Sasuke, it could create a new dynamic. Sasuke might be initially jealous of Naruto's new power but then realize they can work together better. For example, Sasuke's fire - based attacks could combine with Naruto's ice - make to create steam - based jutsus. With Sakura, she might be more protective of Naruto as she fears the ice - make ability could harm him or be a sign of some deeper trouble.
His relationship with his teachers would also be different. Iruka would be extremely proud but also a bit worried about Naruto getting too cocky with his powers. Kakashi, on the other hand, would be more focused on training Naruto to control and master these powers. Naruto's new powers could also attract the attention of other ninja villages. This would put pressure on his relationships with the people in his own village as they might see him as a potential target or a valuable asset. Some might be jealous, while others would be more eager to be his ally.
His friends in Konoha like Shikamaru and Kiba would see Naruto in a new light. They might rely on him more for protection, but also feel a bit of distance because of his elevated status. Naruto would have to work hard to maintain his old friendships and show them that he's still the same person deep down.
His relationship with Hinata would be greatly affected. Hinata would be constantly worried and by his side, trying to support him in every way possible. With his friends like Shikamaru and Kiba, they might become more serious and less carefree around him, always thinking about how to help him through this tough time.
For Frisk, they might see Sans in a new light. Instead of the cool and mysterious Sans they know, he's now a helpless baby. Frisk could become very protective, using their determination to keep baby Sans safe. And the monsters in the Underground would likely be more gentle and patient around baby Sans, changing the overall dynamic of the community.