One possible plot could be that Naruto, feeling ostracized in Konoha due to his jinchuriki status, decides to join Orochimaru. Orochimaru, seeing Naruto's potential, trains him in some dark and forbidden jutsus. Naruto might start to change, becoming more cynical. He could use his newfound powers against those in Konoha who once shunned him, leading to a series of battles between him and his former friends like Sasuke and Sakura.
His character would likely become more conflicted. He has always been a positive and determined person, but being around Orochimaru would expose him to a lot of darkness. He might start to question his own beliefs and values. For example, he may become more ruthless in battle as he adopts some of Orochimaru's combat styles.
If Naruto were to join Orochimaru in fanfiction, it would be a huge deviation from the original story. Naruto's values of loyalty and friendship would be put to the test. He might start to see the world from Orochimaru's perspective, which is often self - serving. This could also mean that Naruto would be involved in Orochimaru's plans to gain immortality, perhaps even becoming a part of his body - swapping experiments in some extreme cases.
In this type of fanfiction, it might also be that Naruto joins Orochimaru to spy on him. The Hidden Leaf Village realizes they need to know Orochimaru's plans from the inside. Naruto, being the brave and somewhat reckless one, volunteers for the mission. He endures Orochimaru's experiments and teachings while secretly sending information back to the village. Eventually, when the time is right, he betrays Orochimaru and uses the knowledge he gained against him.
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.
The story could develop in a dark direction. Naruto might start to learn Orochimaru's jutsus. His personality could become more cynical. He'd be cut off from his usual support system in Konoha.
In some fanfics, Naruto might use his new and powerful jutsu that he has mastered over time. Maybe he combines his Sage Mode with the power of the Nine - Tails in a unique way that Orochimaru can't counter. For example, he could use the Nine - Tails' chakra to enhance the range and power of his Sage Mode attacks, and then catch Orochimaru off - guard.
One consequence could be a shift in the power balance among the ninja villages. Since Orochimaru was a powerful and feared figure, his death might cause some chaos as his former allies or subordinates try to either avenge him or claim his resources. For example, some of his secret labs and experiments might be up for grabs, leading to potential conflicts.
In a fanfic where Naruto joins Madara, it could start with Madara convincing Naruto that his way of achieving peace is more efficient. Madara might show Naruto the dark underbelly of the ninja world that has been hidden from him. Naruto, being the naive but kind - hearted person he is, could be swayed into thinking that Madara's extreme methods are necessary for a long - lasting peace. But of course, this would lead to a lot of internal conflict within Naruto as he goes against his friends and the village he loves.
If Naruto joined Sound in a fanfic, it would completely change the Naruto universe. His relationships would be flipped. Instead of being with Konoha friends like Sasuke and Sakura, he'd be among Sound ninjas. His training might take a different turn too, perhaps learning more brutal and underhanded techniques. This could also lead to a different set of battles and power dynamics in the story.