I think young Sasuke would have a very intense reaction. He was so consumed by his hatred for Itachi at that young age. A Sasuke vs Itachi fanfiction would be like a trigger for him. He would be eager to see how the fictional fight is portrayed. If Sasuke in the fanfiction is shown as strong, it might fuel his own ego and make him strive even harder to become powerful. However, if the fanfiction shows Itachi as superior, it could enrage him. He might feel that it undermines his own goal of defeating Itachi and he might even want to find the writer to correct their 'wrong' view.
The Uzumaki family might be a bit shocked at first. But Naruto's kind - hearted nature could make them eventually come around. His mother Kushina might be more accepting as she always wanted Naruto to be happy. As for Sasuke's family, well, it's a bit more complicated. Since Sasuke is the last of the Uchiha, his family's traditional values might be a hurdle. However, if Sasuke is determined, he might be able to convince any remaining family members or those who care about the Uchiha legacy that his relationship with Naruto is a positive thing.
Well, a number of fans are divided. Some feel that the insults are a form of character assassination for Sasuke, as they view him as a more complex and redeemable character than one who would just randomly insult Sakura. Others, though, might see it as a way to explore the darker side of their relationship and how Sakura can grow from being insulted and become an even stronger character.
He could also be initially confused. Sasuke has known Sakura for a long time, and this unexpected act from her would leave him wondering about her motives. He may hold back his anger for a while to hear her out and understand why she did such a thing.
Sakura would probably be initially very angry. She has strong feelings for Sasuke, but kidnapping is a very extreme act. So she would likely fight back, using her medical ninjutsu skills and combat abilities to try and escape.
Sakura might initially be very angry. She has her own strength and pride, and being kidnapped by Sasuke, someone she once cared for deeply, would be a huge blow to her self - esteem. She could try to fight back immediately, using her medical ninjutsu skills and combat training to attempt an escape.
Kakashi would be more reserved but still show his support. He might give Sasuke some advice on being a father based on his own experiences with his team. Shikamaru would be practical, thinking about how the baby will affect the village's future and offering some logical solutions to any potential problems that might come up.
At first, Hinata's reaction might be one of shock and disbelief. She has probably never expected Sasuke to do such a thing. However, she is a strong - willed character deep down. So, she might start to plan her escape. She could use her knowledge of the ninja world and her own family's techniques. She might also try to find out if Sasuke has any allies or if there are other forces at work. She could try to turn the situation around and make Sasuke realize that what he is doing is wrong by appealing to his better nature or by using her own skills to outwit him.
Naruto would probably be really angry at first. He's a free - spirited person who doesn't like being forced into things. So he'd likely try to fight back right away, yelling at Sasuke about what he's doing.
Sakura might be heartbroken. She's been in love with Sasuke for so long. She could initially go into denial, thinking it's just a temporary thing. Then she might get angry and vow to prove herself to Sasuke, perhaps by becoming an even stronger ninja.