Naruto's reaction could be complex. Since he has his own feelings for Sakura, this situation could stir up a lot inside him. He might initially be a bit hesitant in how to approach her because he doesn't want to overstep any boundaries. But in the end, his natural instinct to help a friend would take over. He would listen attentively to Sakura, his eyes full of determination to make her feel better, and use his own unique way of thinking to give her advice or just be a shoulder to cry on.
Sakura may react with a sense of urgency. She would drop whatever she was doing and rush to Naruto's side. She'd be worried that something truly terrible has happened. If Naruto is hesitant to talk, Sakura might just sit quietly with him, waiting for him to open up. This would show her patience and understanding, and also how much she values Naruto as a friend.
Well, Naruto might try to comfort Sakura. He's always been there for his friends. He could use his own experiences of feeling lonely or left out to relate to her and tell her that things will get better.
Naruto might be very forgiving right away. He has always had a big heart and cared deeply for Sakura, so he could just accept the apology with a big grin and say it's all in the past.
Naruto could also feel a deep sense of hurt. After all, he has been through a lot with Sakura. In the face of her betrayal, he might start to question his own judgment of people. However, being Naruto, he would not give up easily. He might try to find a way to redeem Sakura or at least make her see the error of her ways. He would draw on his own experiences of being ostracized in the past and use that to try to understand her actions and find a solution.
In the long run, this confrontation could be a turning point. If they overcome their differences, it could lead to a deeper and more mature relationship. For example, they might start to respect each other's views more and work together more effectively in future adventures.
She might be heartbroken. Sakura could initially be in shock and then fall into a deep sadness. She may blame herself for Naruto's leaving, thinking that she could have done something differently.
At first, Naruto might be extremely shocked. He trusts Sakura as a teammate and friend, so being kidnapped by her would be completely unexpected. He would likely try to talk to her, asking her why she's doing this.
He may try to talk to Sakura and understand her reasons. Naruto is a character who believes in the goodness of people. So, instead of getting angry immediately, he would likely want to resolve the issue. He could also become determined to prove himself to Sakura, that whatever she thinks he has done wrong, he is actually not that person.
However, in other cases, Naruto could be hesitant. He might have grown so used to their friendship that the idea of a romantic relationship with Sakura is a bit overwhelming. He could take a step back and say something like 'Sakura, this is really unexpected. I need some time to think about this.' This would then lead to a more complex exploration of their relationship in the fanfiction.
He may also choose to defend himself without really fighting back. Naruto values Sakura as a friend and teammate, so he would be reluctant to harm her. He might just try to dodge her attacks and keep talking to her, hoping to snap her out of it.