Perhaps in this fanfiction, Naruto breaks a seal or a power that was related to Kushina. It could be a power that was passed down from her, but Naruto, in his journey to become stronger and more independent, decides to break it. This could have significant consequences for the plot, such as changing his abilities, his relationships with other characters, and his understanding of his heritage.
Well, Naruto might break a bond with Kushina in the fanfiction. Maybe he finds out some dark secret about her that makes him question their relationship.
Naruto might first be in denial. He would find it hard to believe that his mother would break a promise to him. But as the truth sinks in, he could become angry. He might lash out, either physically or verbally, at those around him who remind him of the broken promise. Eventually, he would probably turn this pain into motivation to prove himself despite the setback.
Another aspect could be that the fanfiction delves into how Kushina's presence affects Naruto's relationships with others. For instance, his relationship with Sasuke could be different. With a strong maternal figure in his life, Naruto might be more stable emotionally and be able to approach Sasuke in a more understanding way, which could potentially change the whole dynamic of their rivalry and friendship.
Perhaps Kushina promised to teach Naruto a certain jutsu or pass on some important family knowledge. Breaking this promise could set Naruto on a different path in his ninja training. He might have to seek out other sources or develop his own techniques, which could make his journey more difficult and filled with self - discovery.
In some fanfictions, the authors might take creative liberties and create alternate universes where Naruto and Kushina interact in different scenarios. For example, they could be on a joint mission together, and through that, we see their personalities shine. Kushina's fiery nature and Naruto's determination would make for an interesting dynamic.
One possible fanfiction could be about Kushina finding Naruto in a situation where he's lost in a forest. Maybe she uses her unique chakra sensing abilities to track him down. It could be a heartwarming story of a mother reuniting with her son.
In certain fanfic concepts, Naruto could have found a special relic or artifact. This relic might have the power to reverse death. Since Naruto is always on adventures and exploring different places, he might stumble upon such an item and use it to revive Kushina. It could also be related to the Uzumaki clan's secrets that he uncovers which enables him to bring his mother back.
Minato could be a common character. Since he was Kushina's husband in the original story, his presence might add some interesting dynamics to the harem scenario. Another could be Jiraiya. His connection to Naruto and his reputation as a bit of a ladies' man could make for an interesting addition to the story.
One possible reason could be for Naruto's protection. Maybe she thought by banishing him from a certain place or situation, she could keep him away from a hidden danger that she knew about. For example, there might be a powerful enemy targeting Naruto specifically, and she believed that by making him leave, he would be harder to find.