Sakura would be devastated. She has always had deep feelings for Naruto, whether it was friendship or something more. She would probably throw herself into her medical work even more, trying to find a way to bring him back, even if it was impossible. Shikamaru, being one of Naruto's friends, would be solemn. He might use his intelligence to figure out what really happened to Naruto, and he would be the one to come up with a plan to deal with the aftermath.
Some Naruto characters would likely be very confident in a Highschool of the Dead - Rei fanfiction setting. For example, Naruto himself would probably jump right into action against the zombies. He'd see it as another challenge to overcome and would use his Rasengan or other jutsus without hesitation. Sasuke, on the other hand, would be more calculating. He'd analyze the situation of the zombie apocalypse and the role of Rei and others before making a move.
Initially, Naruto could be filled with anger. He might feel like all his efforts to protect the village and be accepted were in vain. However, his strong will and belief in himself would likely kick in. He could decide to train even harder, not just to prove his innocence but also to become strong enough to face whatever force was behind his betrayal. He might also start to question the values of the village he once held so dear.
If Naruto was an Ajin in a fanfiction, the characters in Naruto would have a mix of reactions. Hinata would be concerned for Naruto's well - being. She might be a bit scared at first because of his new and strange abilities, but still stand by him. The villagers, who have had a rocky relationship with Naruto in the past, might be afraid of him all over again. They could see his Ajin powers as a threat. On the other hand, Naruto's close friends like Shikamaru would try to understand what's going on and help Naruto control his powers if they can.
Gray would be angry and sad at the same time. He was Natsu's rival but also his friend. He might lash out at first, blaming the situation or other people. But then he would turn his anger into a determination to find out what really happened to Natsu and seek justice if there was foul play involved. And he would also be there for Lucy and the other guild members, trying to keep them strong.
Sakura would be extremely worried. She would probably try to gather the other members of Team 7, like Sasuke and Kakashi, to go after them. Sasuke might be a bit more hesitant at first, but his loyalty to Naruto would eventually make him join the search. Kakashi, on the other hand, would be more strategic. He would try to figure out Minato's motives first and then plan the rescue mission accordingly.
The characters in 'Naruto' would be deeply affected if Naruto dies at birth in fanfiction. Jiraiya would be one of the most affected. He saw Naruto as his protege and the hope for the future. Without Naruto, Jiraiya might lose his enthusiasm for training and spreading his teachings. Tsunade would also be saddened as she had a connection to Naruto through her relationship with Jiraiya and Minato. The Rookie 9, Naruto's friends, would have a completely different dynamic. They might not form as tight a group without Naruto's energetic and positive influence. And the Sannin, as a whole, would have their relationships and legacies altered without Naruto in the picture.
Sakura might be a bit surprised at first, but then she would be happy for Naruto. She has always been his friend and would see that he is happy with Shikamaru. Kakashi would probably be very supportive. He has seen both Naruto and Shikamaru grow up and would understand their connection. Sasuke, on the other hand, might not show much emotion on the surface, but deep down he would be okay with it as long as Naruto is happy.
Sakura might be a bit surprised at first, but she would ultimately be happy for Naruto. She has grown past her initial crush on him and would see that Pakura makes him happy. Kakashi would probably be very supportive, seeing it as another step in Naruto's growth and a positive development for the ninja world. Sasuke might be more reserved in his reaction, but deep down he would understand Naruto's choice and respect it.
Sasuke might be initially dismissive but secretly concerned. He would probably keep an eye on Naruto from a distance, not wanting to show too much emotion. Sakura, on the other hand, would be more openly worried and would try to use her medical skills to figure out if there's something physically wrong with Naruto.
Sasuke would be deeply affected. He would probably feel guilty for not being there to save Naruto. At the same time, he would vow to uphold Naruto's ideals and make the ninja world a better place, as a way to honor his friend's sacrifice.