She could also try to reason with Itachi. Sakura is intelligent and might try to understand his motives. She may ask him why he is doing this and try to find a way to negotiate her release. If she realizes that Itachi has a valid reason, she might even cooperate with him to some extent.
Sakura might initially be terrified. She would probably try to fight back using her combat skills and medical ninjutsu to defend herself. Since she is a strong - willed character, she won't go down without a fight.
Sakura would probably be angry at herself for being captured. She's a proud ninja. So she would start looking for weaknesses in Itachi's hold on her. Maybe she would try to engage him in conversation to find out his motives, all the while formulating a plan to break free. She could also try to send out some sort of signal to her comrades if possible.
Sakura would probably be initially terrified. She would try to use her medical ninjutsu skills to defend herself or at least slow Itachi down. If she realizes she can't overpower him physically, she might try to talk to him, asking him why he's doing this.
Sakura would probably be scared at first. But then, being the strong - willed character she is, she might start to talk back to Itachi. She could say something like 'You don't want to do this, Itachi. I know you have your reasons, but this is wrong.' She would try to use her words to defuse the situation.
She might be a bit confused at first. After all, Itachi has a very complex and somewhat dark past. But she could also grow to understand her father's perspective as she learns more about Itachi herself.
There would be other fans who might be intrigued. They like to explore different 'what - if' scenarios in fanfiction. They would see it as a creative way to explore the characters in a new light, even if it goes against the canon. However, they would also be aware that it's just a fictional alternative and not the real Naruto story.
She might be surprised at first. After all, Naruto isn't known for his singing usually. But then she could be touched if she realizes the song is for her and about their relationship, whether it's friendship or something more.
Sakura would probably be horrified. She knows Orochimaru's reputation for being cruel and power - hungry. She would immediately reject any offer from him and get ready to fight if necessary. After all, she has grown into a strong kunoichi and won't be easily intimidated.
Sakura might be heartbroken at first. She has always been in love with Sasuke and to find out he's cheating would shatter her world. She could become withdrawn and focus more on her medical ninjutsu as a way to cope.
Kakashi, as their sensei, would be disappointed. He would hope that they could resolve their differences maturely. He might offer some advice based on his own experiences in relationships, but ultimately it would be up to Itachi and Sakura to decide whether to take it or not.
She would be heartbroken. Sakura has known Naruto for a long time, and his death would shatter her world. She may become more withdrawn and serious. In the long run, she could use her pain as motivation to become stronger. Maybe she would train harder than ever before to make sure that no one else has to suffer the way Naruto did. She might also start to see Naruto in a different light, realizing all the things she took for granted when he was alive.