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.
He might meet the future versions of Naruto and Sakura. Their relationship with him could be very different in the future, perhaps they are now leaders of the village and Sasuke has to adjust to their new status.
In a Sasuke and Sakura parents fanfiction, it could show how their parents' personalities influenced Sasuke and Sakura. For example, if Sasuke's father was known for his strict discipline, it might explain Sasuke's own drive and determination. And if Sakura's mother was a kind - hearted healer, it could be where Sakura gets her nurturing side from.
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.
Sasuke traveling to the future in the fanfiction would be full of possibilities. He could find that the traditional ninja clans have evolved into something completely different. For example, the Uchiha clan may have developed new and unique powers that are a combination of their Sharingan heritage and future technology. He may also meet versions of himself from different timelines, which would create a very complex and mind - boggling situation as he tries to figure out his place in this new future.