Naruto would be devastated. He might blame himself for not being able to protect his son. Sasuke would be angry and would likely go on a hunt for the perpetrator. His friends like Sarada and Mitsuki would be heartbroken. Sarada might vow to become stronger to prevent such a tragedy from happening again.
Well, Naruto would be in a really tough spot. He loves his family and the village, and this situation would be a huge blow to his traditional values. He might struggle to understand how this happened between his son and Hinata. Hinata's family, on the other hand, would be protective of her. Her father would want to ensure that Boruto is taking responsibility. Boruto's friends would also be surprised. Some might be supportive, like Shikadai, who would try to see the good in the situation, while others might distance themselves at first, not sure how to handle this new and rather strange development.
Boruto could be developed by showing his growth in responsibility. For example, in the fanfic, he could take on the task of teaching Himawari a new jutsu. This would not only show his skills but also his patience. Himawari, on the other hand, could be developed by showing her becoming more independent. Maybe she decides to go on a small mission on her own to prove herself to Boruto.
The main characters in Boruto anime story include Boruto Uzumaki, who is on a journey to make his own mark as a ninja different from his father. Sarada Uchiha, with her determination to become Hokage and her Uchiha heritage. Mitsuki, who has an interesting backstory related to Orochimaru. There are also other characters like Naruto Uzumaki, who still plays a significant role in the story as Boruto's father and the Hokage of the Hidden Leaf Village.
Boruto himself is quite interesting. His rebellious nature against the established order of the ninja world yet his underlying good heart makes him a complex character. Then there's Kawaki, with his mysterious past and his connection to Boruto. Sarada, as the daughter of Sasuke and Sakura, also has an interesting mix of her parents' traits.
Naruto is likely to be popular too. Even though it's a Boruto x Sasuke fanfic, Naruto's relationship with both of them is so important. He could play a role in supporting them from the sidelines or even getting involved in a crucial part of the story.
Sasuke is very likely to be involved. He has a close relationship with Naruto and is also an important figure in Boruto's life. His skills and knowledge could be crucial in any adventure or situation that Naruto and Boruto find themselves in. Another character could be Hinata. As Naruto's wife, she would surely be concerned about any strange events involving Naruto. And for Boruto, she is his mother, so she would play a role in any family - related or village - threatening situations.
Sarada could also be a main character. She is strong - willed and intelligent. She could be investigating a case of a missing - nin who is suspected of being involved in some sort of conspiracy against the Uchiha clan. This would give her a chance to show her detective skills and her loyalty to her clan.
No, Boruto is alive in the manga. The plot hasn't led to his death. However, the manga is ongoing, and anything could happen in the later developments.