In some fanfictions, Team 7 might hurt Naruto through their words. For example, Sasuke could say something really mean about Naruto's lack of skills compared to his own in the beginning. Sakura might also be dismissive of Naruto's feelings for her in a hurtful way, which could make Naruto feel isolated within the team.
Sasuke might become more withdrawn. He was always in a sort of rivalry with Naruto, and without Naruto there, he could lose some of his motivation to get stronger. Sakura would be devastated. She cared about Naruto, and his leaving would make her question what went wrong. Kakashi would also feel a sense of failure as a teacher.
At first, Naruto would be extremely hurt. He has always considered Team 7 as his family, so their betrayal would be a huge blow. He might go into a state of shock and disbelief.
The writer can focus on Naruto's emotions. Show his shock and disbelief when the hurt occurs. For example, if Sasuke attacks him, describe how Naruto's eyes widen in horror, unable to believe that his friend would do such a thing. Use internal monologue to let the readers know how broken Naruto feels inside. Another way is to show the physical pain in detail, like if Sakura uses her medical skills to harm rather than heal Naruto, describe the pain as it courses through his body.
In some fanfictions, Sakura might accidentally hurt Naruto during a training session. Maybe she uses a new jutsu she's not fully mastered and it goes wrong, hitting Naruto instead of the target.
Well, in some Narusaku fanfictions, Sakura might hurt Naruto emotionally by choosing Sasuke over him repeatedly. This can make Naruto feel rejected and unloved, causing him pain.
In some Sasunaru fanfictions, Sakura might hurt Naruto emotionally. For example, if she chooses Sasuke over Naruto in a very cruel way, it can break Naruto's heart. She could say mean things about his dreams or his past as an orphan, which would deeply wound him.
Well, the team's reaction can vary depending on the specific circumstances in the fanfiction. Sometimes they are angry, especially if they think the injury was preventable. They'll do whatever it takes to get revenge on the cause of Keith's hurt if it was due to an enemy attack. And they'll also be there for Keith during his recovery, sharing stories, and trying to keep his spirits up so he can heal faster.
Well, it could make the team more protective. Sasuke might feel a stronger sense of rivalry as he wants to be the best in the team even with Naruto in this new role. Sakura would probably be very motherly, always fussing over Naruto. And Kakashi would have to adjust his teaching methods to accommodate Naruto's new situation.
Naruto would probably be extremely hurt and confused at first. He would try to talk to his teammates, to understand why they are doing this. He might plead with them, asking them to remember their past together. But when he realizes they won't listen, he could become angry. Naruto has a strong will, so he would likely decide to prove his innocence on his own, vowing to show Team 7 that they are wrong.
He could also get angry. Naruto has a strong sense of justice and loyalty. So, being betrayed might fuel his anger, and he could set out to prove his innocence on his own. He might go on a journey to find evidence that clears his name and also to become stronger so that he can face his former teammates if they become enemies. He might also start to rely more on other friends outside of Team 7, like Shikamaru or Rock Lee, who might believe in him from the start.