Well, in a fanfic where Naruto joins Orochimaru, perhaps Naruto is tricked by Orochimaru. Orochimaru might promise Naruto a way to control the Nine - Tails better. Naruto, being naive at that moment, follows him. Once with Orochimaru, Naruto discovers Orochimaru's true intentions of using his body. But by then, it's hard to escape. He has to figure out a way to outwit Orochimaru while also dealing with the dark influence of Orochimaru's lair.
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.
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.
One possible plot could be that Naruto, as Orochimaru's son, struggles with his identity. He might have Orochimaru's scientific genius but also Naruto's determination. He could be shunned by the village at first due to Orochimaru's bad reputation. But then, he uses his unique skills to prove himself, perhaps by developing new jutsu that combines Orochimaru's snake - related techniques with Naruto's own chakra - based powers.
Well, one possibility could be that Naruto, with his ninja skills and strong sense of justice, joins Slade for a common goal like fighting a greater evil that neither could face alone. Maybe they team up to take on a powerful, shadowy organization that threatens both their worlds.
Well, one possible plot could be that Naruto, disillusioned with the Hidden Leaf Village after some major betrayal. He might start to see the Akatsuki's goals in a different light. For example, if the village wrongly accuses him of a crime he didn't commit, like they did with Sasuke in some ways. He could then be approached by an Akatsuki member who offers him a place in the group where he feels he can be understood. And Naruto, in his search for a new purpose and a place to belong, decides to join.
In a 'naruto joins obito fanfic', it could start with Naruto being transported to a parallel dimension where Obito has already started his own ninja village. Naruto, seeing the potential in Obito's ideas but also the flaws, decides to join him. He helps Obito to correct his path. For example, Naruto could teach the ninjas in Obito's village about the importance of hope and not giving in to hatred. They could then work together to build a village that is a model for the rest of the ninja world, based on both Obito's and Naruto's ideals.
One possible plot could be that Naruto, disillusioned with the Hidden Leaf Village for some reason, like being wrongly accused or feeling betrayed. He then decides to join the Akatsuki. He might bring in new jutsu and a different way of thinking to the organization. His goal could change from protecting the village to perhaps finding a new way to bring peace in a more radical way.
One possible plot twist could be that Sakura initially joins Orochimaru to gain more power to protect her friends, but she soon discovers that Orochimaru has ulterior motives regarding her unique chakra abilities. For example, he might want to use her as a vessel for some dark jutsu. Another twist could be that Orochimaru's henchmen start to develop loyalty towards Sakura instead of him because of her strong will and medical skills. This could lead to a split within Orochimaru's group, with some siding with Sakura and others remaining with Orochimaru.
Maybe in this fanfic, Naruto has been influenced by some dark force or a traumatic event that makes him turn to Orochimaru. Orochimaru, seeing Naruto's potential, convinces him to work together. Naruto's tasks could involve helping Orochimaru in his experiments. However, as time passes, Naruto realizes the true evil nature of Orochimaru and has to struggle between the loyalty he feels due to the power he's gained and his own moral compass.
Well, it could be that Naruto, feeling neglected in his own village, decides to seek a new start in Kumo. Maybe he meets some unique characters there who accept him for who he is and he begins to train in their style of jutsu, thus becoming a stronger shinobi in a new environment.
In this fanfic, it could be that Naruto is on a mission to bridge the gap between the major villages and the smaller ones like Amegakure. He teams up with Konan as she has a deep connection to Amegakure. Naruto's presence in Amegakure could attract other powerful shinobi to join them. They could then form an alliance within Amegakure that is based on equality and mutual respect, and start to change the perception of Amegakure in the shinobi world.