Well, one possible plot could be that Naruto grows up in the Marvel universe with Tony Stark as his father. He might inherit some of Stark's technological genius along with his own ninja skills. Maybe he uses his chakra to power up some of Stark's suits in unique ways, creating a new kind of superhero hybrid.
Well, often there's the theme of identity. As an original character who is the son of Brandon Stark, he has to figure out his place in the world. There could also be themes related to honor, like how he upholds the Stark honor in difficult situations. Maybe he has to deal with the dark side of the political games in Westeros while still staying true to his family's code. And sometimes, themes of love and friendship also play a part, like how he forms relationships with other characters in the story.
There could be some characters from outside the North as well. For example, a wandering knight who is impressed by Harry's courage and Stark - like qualities. Or perhaps a foreign noble who has heard of the Starks' reputation and sees Harry as a means to gain influence in the Westeros. These unexpected allies could bring new perspectives and resources to Harry's cause.
Well, it could make the son grow up feeling unloved and insecure. He might become withdrawn, always seeking approval but never quite believing he's worthy. This could lead to him having problems in relationships later in life, constantly doubting others' intentions towards him.
There could be a plot where Tony's past mistakes come back to haunt him, and he's worried about how it will affect Peter. He might try to distance himself from Peter to protect him, but Peter doesn't understand and feels rejected. This would lead to a rift between them. However, in the end, they would reconcile as they realize how much they mean to each other as father and son.
Yes, in certain fanfiction stories. This concept can bring a lot of changes to the existing Marvel narrative. For example, it could change how Peter inherits Stark's technology. Instead of just being a mentee, he could be the rightful heir. It also might affect how other characters interact with Peter. They could view him as more of a significant figure in the Stark legacy, and it could create more complex story arcs involving family secrets and power inheritance.
I'm not sure about specific 'oc son of brandon stark fanfiction' off the top of my head. However, if you join some Game of Thrones or Stark - related fan communities on social media platforms like Reddit or Discord, you can ask the members there. They are often very knowledgeable and can point you to some really good fanfictions in this area. They might even have written some themselves.