One possible plot could be that Naruto discovers a way to travel back in time and decides to save his mother, Kushina. As he gets to know her better during this time - saving her from threats and sharing his future knowledge with her - their relationship deepens into love, and they end up getting married. It could also involve Naruto having to deal with the consequences of changing the past in terms of how it affects the future he came from.
Well, in some fanfictions of 'naruto marries kushina', there could be a plot where Naruto somehow travels back in time. This allows him to meet Kushina in her younger days. He then uses his knowledge from the future to win her heart in a very unique way. Maybe he shows her all the great things that will happen to their son in the future, which makes Kushina fall for him.
Naruto could develop a stronger sense of responsibility. He is marrying Kushina, so he has to take care of her and think about their future. This might lead to him being more cautious in his actions. Kushina, on the other hand, may develop a more open - minded attitude. She might start to accept new ideas and ways of life that Naruto brings to her.
One way to write it could be to have Naruto somehow gain the ability to time travel. Maybe through a powerful jutsu gone wrong. He then travels back in time and meets a young Kushina. He already has feelings for her because of his motherly connection to her in his own time. He could start by helping her out in small ways, and over time, they develop a romantic relationship that leads to marriage.
A significant difference would be the power dynamics. In the original, Naruto gains power through his own hard work, training, and the power of the Nine - Tails. In a fanfiction where he marries Kushina, there could be new power - sharing elements. Maybe they combine their Uzumaki chakra in unique ways. Also, the social aspect is different. In the original, Naruto is seen as an orphan trying to find his place. Here, he is part of a powerful couple. This changes how the other characters interact with him and how the story progresses in terms of village politics and alliances.
In a time travel fanfiction where Naruto marries Kushina, the impact on the Naruto world would be multi - faceted. Genetically, it's a very strange situation. But if we look past that, politically, their union could bring about peace faster. Since Naruto has the ideals of the future and Kushina has the influence of her clan in the past. Socially, it would shock many. People would have to adjust to this new relationship. And in terms of the ninja arts, Naruto could teach Kushina some future techniques, and she could pass on her unique skills to him, changing the way battles are fought in that time period.
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.
It could be Sasuke's sister, if there was one in the fanfiction world. She might share some of Sasuke's traits but also have her own unique personality that attracts Naruto.
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.