Perhaps in this fanfiction, Naruto has some sort of special power or transformation that he unlocks just in time to face Orochimaru. It could be related to his Nine - Tails chakra in a new and unique way. He uses this power to break through Orochimaru's defenses and save Hiruzen. Naruto might also use his knowledge of Orochimaru's weaknesses that he has learned either from Jiraiya or from his own past encounters with Orochimaru's minions.
Naruto would be deeply hurt. He has grown up with so little love and acceptance in the village, and Hiruzen was one of the few people he thought cared for him. His reaction could involve a lot of self - reflection. He might question his own worth and what he has done wrong. But ultimately, his positive nature would take over. He would try to understand Hiruzen's reasons, even if he didn't agree with them. And he would strive to find a way to reconcile and make Hiruzen see that he is not a threat.
Sakura would be heartbroken. She'd likely spend hours upon hours by Naruto's side, trying to jog his memory with stories of their adventures together. She might even get a bit overbearing in her attempts. Sasuke, who has his own complex relationship with Naruto, would be conflicted. He'd see Naruto's forgetfulness as a sign of weakness at first but then realize the importance of their bond. Kakashi, being the experienced leader, would start by observing Naruto carefully to see exactly how much he has forgotten and then start a systematic process of helping him remember.
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.
Sasuke would likely be devastated. Despite their past differences, Naruto was his rival and in a way, his closest friend. He might go into a deep state of regret and isolation. Sakura would be heart - broken. She loved Naruto, and his death would be a huge blow to her. She might become more withdrawn and focus all her energy on her medical ninjutsu. Kakashi would be filled with a sense of failure. He was Naruto's teacher, and he would feel responsible for not being able to protect him.
Sasuke might initially be indifferent on the surface, but deep down he would feel a sense of loss. He has always had a rivalry with Naruto, and Naruto's departure would mean an end to that dynamic. Sakura would be devastated. She has grown to care about Naruto as a friend and teammate, and his leaving would leave a big hole in the team.
Sakura could react with fear at first. After all, Orochimaru is a very dangerous and unpredictable character. But then she might gather her courage and try to use her strength to break free. She could use her punches, which are quite powerful, to hit Orochimaru's snake body.
Naruto would be angry. He's not the type to just accept being kidnapped. He'd immediately start looking for ways to escape. He might try to use his ninja skills to break free from whatever restraints Orochimaru has put on him.
Sakura would be worried sick. She might immediately inform Kakashi sensei and the rest of the village. Then, she would probably want to be part of the rescue mission. Sakura has grown stronger over time and would use her medical ninjutsu and combat skills to help save Naruto. She would also be constantly worried about Naruto's well - being and would encourage the others to move faster.