One possible plotline could be that Naruto's family is in a difficult situation and they believe they can only support his sister. So, Naruto is left on his own. He then has to struggle to survive in the ninja world without the support of his family. He might become more independent and self - reliant, forging his own path.
Another plotline could be that there is some sort of prophecy or danger related to Naruto, and to protect his sister from it, his family decides to abandon him. Naruto, being the strong - willed character he is, could then strive to prove his worth and show that he can overcome whatever challenges are associated with the prophecy. He might also try to find his family again and make them see his value.
It could be that there was a prophecy related to his sister that made the family think she was more important. For example, a prophecy that she would be the key to saving the village in the future. And in their short - sighted view, they abandoned Naruto to focus all their resources on her.
One possible plotline could be Naruto growing up with a sense of deep abandonment and having to face the world alone. This could lead to him having a much more cynical view of life. He might struggle more with controlling the Kyuubi's power as he has no guidance from Kushina. Another aspect could be his relationships with other characters like Iruka or Sasuke being different. Without Kushina's love, he may be more desperate for any form of connection.
One possible plotline could be Naruto feeling extremely lost and having to find his own way to become stronger without their guidance. He might start to question his own worth and abilities, but then he could meet new allies who help him realize his true potential on his own. For example, he could encounter some other outcast ninja who have their own unique skills and together they form a new kind of ninja team that challenges the traditional ways of the ninja world.
One possible plotline could be Naruto growing up on his own, learning survival skills at a very young age. He might become more cynical towards the idea of family. Another could be that he meets someone who becomes like a surrogate family, and through this relationship, he starts to heal his inner wounds. He could also start to search for the reasons why his family abandoned him, leading to a journey of self - discovery.
Perhaps Naruto, after being abandoned by Minato, falls in with a group of outcasts. Together they form a sort of family of their own. Naruto's natural leadership and kind heart start to shine through as he tries to protect this new family. As he uncovers more about his past and Minato, he has to decide whether to forgive his father or hold on to his anger. This internal struggle could be a major part of the fanfiction.
Perhaps there could be a plot where Naruto's twin sister gets into some kind of trouble, like being kidnapped by an enemy ninja clan. Naruto then goes on a desperate mission to rescue her. During this time, he realizes just how much she means to him. He uses all his skills and the power of his friends to get her back, and in the end, their bond becomes even stronger.
One possible reason could be jealousy. Maybe his sister is jealous of Percy's special abilities or the attention he gets. Another reason might be that she is forced to abandon him due to some external threat or danger that she believes will harm her if she stays with Percy. Or perhaps she has been brainwashed into thinking that Percy is a bad influence or a danger to her.
One possible plotline could be Naruto growing up with his uncle and learning different jutsu from him. His uncle might have a unique style of teaching that helps Naruto develop his skills faster. Maybe his uncle also has some secrets about Naruto's family that he gradually reveals as Naruto gets older.
A possible plotline is that Naruto gets adopted by a group outside the village. He grows up learning their ways and becomes a sort of outcast from Konoha. Then, he could return to the village with a different set of skills and a new perspective. Or, he might develop a vendetta against Konoha for allowing his abandonment and try to take revenge in some way.
Well, sometimes in fanfiction, the author wants to explore the theme of loneliness. So they create a scenario where Naruto's friends abandon him because they are influenced by the village's elders. The elders might spread false rumors about Naruto to maintain their control. His friends, being young and naive, believe these rumors and turn their backs on Naruto, which then leads to Naruto's journey of self - discovery and growth in solitude.