If Naruto merged with Yami Naruto in fanfiction, he could potentially access a whole new level of chakra. Yami Naruto has a different kind of energy, and when combined with Naruto's own chakra, it might create a more powerful and unique form of energy. This could give him an edge in battles, allowing him to defeat enemies that he previously couldn't. Also, his appearance might change, taking on some of the more menacing features of Yami Naruto.
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.
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 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.
Well, Naruto's mental state could be affected. Since Kurama has a very strong will, Naruto might have to struggle more to keep his own personality intact while merged. On the other hand, it could also lead to a deeper understanding between them, which in turn could result in Naruto being able to access Kurama's memories and knowledge. This could give him an edge in battles as he might learn about ancient fighting techniques or secrets of the ninja world.
If Naruto merged with the Juubi in fanfiction, it could completely change the Naruto universe. His physical strength would skyrocket. Imagine him being able to withstand attacks that would normally obliterate a normal ninja. His Sage Mode and other forms might be enhanced to a level that we can't even imagine. And he might develop a new form that combines his own features with those of the Juubi, making him look both like himself and the fearsome beast.
Well, one possibility is that Naruto would gain Hashirama's insane wood - style jutsu abilities. He could use it to create massive forests for cover or to bind enemies in an instant. His already strong chakra would likely be enhanced even further, making him an even more formidable opponent. Maybe he could also inherit Hashirama's leadership qualities and be even better at uniting the ninja clans.
You could look for fanfictions on platforms like FanFiction.net or Archive of Our Own. Try searching with the exact phrase 'Orochimaru trains Naruto' and then filter through the results to find ones that are well - written. Some might focus on Orochimaru teaching Naruto forbidden jutsu in a way that doesn't corrupt him but instead enhances his abilities.