Well, Naruto is a complex character. Initially, he may feel a sense of confusion. He might wonder why he is being forced when he has his own ideas about what he wants to do. He could also feel a bit of fear, not really knowing what being a ninja fully entails. He might be worried about whether he can meet the expectations that come with this forced role.
Naruto would face the challenge of self - discovery. Being forced into the ninja life, he has to figure out if he can actually find something positive in it. He also has to face the danger that comes with being a ninja. With his initial reluctance, he may not be as prepared as those who willingly entered this path. And there are the political aspects within the ninja world that he'll have to navigate, which can be especially difficult when he didn't choose to be part of it.
Well, often in fanfiction, Naruto's growth as a better ninja comes from his increased understanding of the nature of chakra. He might discover new ways to manipulate it, like fusing different types of chakra in a more efficient and powerful way. This could lead to him developing new and stronger ninjutsu, making him a more formidable ninja.
At first, Naruto would be in disbelief. She has always seen Sasuke as a friend or a rival, not a marriage partner. So, she would likely be very vocal about her opposition. She might gather her friends, like Sakura and Kakashi, to support her cause. She could also try to appeal to Sasuke's sense of justice. Since Sasuke has his own code of ethics, he might also not be happy about this forced situation. Naruto could use this to try and find a way to break free from this unwanted marriage.
At first, Naruto might be angry. He's put in a lot of effort to get into the ANBU and prove himself. So being forced out would feel like a slap in the face. He might go on a rant about how unfair it is.
Well, he might be super excited at first. Naruto is always eager to learn new and powerful techniques. Flash Step is a very cool and useful ability, so he'd probably be like a kid in a candy store, full of energy and anticipation, ready to master it as soon as possible.
Naruto might be initially excited. He's always eager to learn new and powerful jutsu, and the Chidori is a very cool and strong one. He probably can't wait to start training and show off to his friends once he masters it.
Well, Kushina could initially be disappointed. But then she might see it as an opportunity to help Naruto find his true passion. She could start introducing him to different things, like maybe some traditional Uzumaki family skills that don't necessarily involve being a ninja in the typical sense. This way, Naruto could still have a sense of purpose and connection to his heritage.
Well, he might be in shock at first. I mean, Sirius is like a godfather to him, so the idea of marrying him is completely out of the ordinary. He could be filled with disbelief and confusion, not knowing how to even begin to process this strange turn of events.
He might become a simple farmer. Without the ninja path, Naruto could focus on growing crops and living a peaceful rural life. He would be away from the battles and politics of the ninja world, and just enjoy the simple pleasures of nature.
It might inspire other writers in the community. Some might see it as an opportunity to fill the gap and start creating their own unique takes on Naruto - related stories. For example, new writers could emerge trying to recreate the kind of stories the 'quitting' writer used to write.