It's a very strange concept for a fanfic. Naruto is known for his strong bonds with his friends. In the Naruto universe, friendship is a major theme. So for him to get revenge on his friends would mean something really bad must have happened. It could be an interesting fanfic if the writer can come up with a really good backstory to justify it. For example, if his friends were somehow mind - controlled and did things that hurt Naruto deeply. But overall, it's not something we'd expect from the Naruto we know.
In most 'Naruto gets sick' fanfics, his friends are very concerned. For example, Sakura will immediately start using her medical skills to diagnose and treat him. Sasuke, although he may not show it outwardly as much, will stay by Naruto's side and keep a watchful eye. Shikamaru might come up with plans to make Naruto more comfortable during his illness. And Hinata, she would be really worried and would probably bring Naruto some home - cooked food to help him regain his strength.
His friends would most likely rally around him. Kiba might use his dog Akamaru to scout the area and make sure there are no other immediate threats. Hinata would be really worried and would try to use her Byakugan to see if there are any hidden enemies or if Naruto has any internal injuries. Choji would offer some of his food to Naruto to give him strength, as his clan's food can have special effects on a ninja's body.
I think Naruto's friends would be quite shocked. For the more traditional ninja like Neji (if he were still alive in this fanfic), he would see the gun as an abomination to the ninja way. However, Naruto's closest friends like Kiba would be more open - minded. Kiba might see it as a cool new weapon and want to see what it can do. But overall, they would all be concerned about how Naruto got the gun and what it means for their world of ninjas.
In a fanfic, Naruto could be driven to get revenge on his friends if there was a prophecy or some sort of fated event that made him believe they were going to be his downfall. Also, if his friends made a deal with an evil force to gain power at the expense of Naruto or his loved ones, he might feel the need to take revenge. Another factor could be extreme jealousy. If Naruto's friends suddenly got all the attention and recognition that he felt he deserved, and they flaunted it in a mean - spirited way, it could push him over the edge.
One possible plot could be that Naruto discovers his friends have been secretly working with an enemy. They might have been promised power or something valuable in return for betraying Naruto. Maybe they spread false rumors about Naruto, turning the village against him.
Naruto would likely become more distrustful at first. He's always been so open and trusting of his friends, so this betrayal would shatter that. He might become more withdrawn, constantly second - guessing people's motives.
In such a fanfic, the plot might involve Naruto finally realizing the unjust treatment he received from the villagers in his past. He could start by using his powerful ninja skills, which he has honed over the years. Maybe he begins with small acts of disruption, like causing minor chaos during village festivals. Then, as his revenge plan unfolds, he might target the village's infrastructure, such as disabling the security systems. However, this would likely be a complex story as Naruto also has friends in the village who would try to stop him and make him see reason.
One common theme is betrayal. Naruto might feel that Konoha has betrayed him in some way, like hiding important information or not standing up for him when he needed it. This sense of betrayal then drives his revenge.
In the fanfiction, Naruto might think his family abandoned him on purpose. So, he starts to seek revenge. He could train hard to become extremely powerful. Along the way, he meets some people who try to convince him that revenge is not the answer. But his anger is so strong that he doesn't listen at first. Eventually, he might come across some evidence that shows his family had no choice but to leave him, which makes him question his revenge mission.