Well, Orochimaru's immortality would mean that his influence would be long - lasting. He could continue to conduct his unethical experiments over a very long period. This might lead to the creation of new and dangerous ninja techniques or even new forms of life. In the long run, it could change the way ninja are trained and how the ninja world views power and knowledge. For example, some might start to see immortality as the ultimate form of power and strive for it at all costs. Naruto and his friends would have to constantly be on guard against Orochimaru's schemes.
In this fanfiction, their relationship could be full of tension. Orochimaru is a character who often pursues power through unorthodox means. Naruto, on the other hand, values life and friendship. So, they would constantly be at odds. But at the same time, there would be a sense of loyalty between them as brothers. Orochimaru might try to manipulate Naruto at times, while Naruto would be trying to redeem his brother, leading to a very tumultuous relationship.
The story would also change in terms of Naruto's relationships. His friends like Sasuke and Sakura would be very concerned and might try to stop him. This could lead to a rift between them. Naruto might gain new powers faster, but at a cost. He could start to lose his connection to his normal self and the Nine - Tails inside him might react negatively to the experiment.
In a fanfiction like this, Orochimaru could train Naruto in the ways of stealth and assassination, skills that Orochimaru is quite proficient in. Naruto would initially be hesitant but realizes that these skills can be used for good. For example, to infiltrate enemy bases and gather intelligence to prevent wars. This would change Naruto's fighting style and make him more versatile in the shinobi world.
Naruto could be related to Orochimaru in a fanfiction through a family - like bond. Maybe Orochimaru has a past connection to Naruto's family that was previously unknown. It could be that Orochimaru had a debt to Naruto's father or some other relative, and this leads to an unexpected relationship where Orochimaru feels obliged to protect or guide Naruto in some way.
In this kind of fanfiction, Naruto might have used his new and powerful jutsu that he developed secretly. Maybe it was a super - enhanced Rasengan with some special chakra nature added to it, which was strong enough to overpower Orochimaru.
Since Orochimaru had many experiments and secrets, his death at Naruto's hands in the Chunin Exams fanfiction could lead to a scramble for his research. Other villages or even some rogue ninjas might try to steal his notes and facilities. In Konoha, Naruto might be pressured to reveal what he knew about Orochimaru's plans and secrets. This could put him in a difficult position as he may not know everything. Also, Sasuke, who had a connection with Orochimaru, might have a complex reaction. He could be angry at Naruto for killing Orochimaru, or he could see it as a sign of Naruto's strength and be motivated to become stronger himself.
Naruto would likely become more secretive. Since Orochimaru is a very private and often devious character, Naruto might pick up some of those traits. He would probably keep things from his friends more often.
Naruto's character development in this fanfiction would be complex. He'd probably grow up with a sense of superiority due to Orochimaru's powerful teachings. But at the same time, he'd lack the warmth and compassion that came from his relationships in Konoha. He might be more self - centered, focused on his own power and survival. He may not have the same sense of justice as in the original Naruto, as Orochimaru's motives are not in line with the general good. And his relationship with his peers would be more of a power struggle. He might not form the same deep friendships, but rather see others as either tools or threats.
Naruto's character would likely become more conflicted. He has always been on the side of good, and joining Orochimaru, even if for a good reason, would put him in a morally gray area. His view of power might change as he is exposed to Orochimaru's unorthodox ways of obtaining it.