Well, when Naruto gets sick in fanfics, his friends react in really endearing ways. Sasuke, who has a complex relationship with Naruto, shows his care in a more subtle way. He might sit quietly in the corner of the room, but his presence is reassuring. Sakura is more hands - on. She scolds Naruto for overworking himself and then gets to work on making him better. Choji might bring Naruto some of his favorite snacks, thinking that good food will help him recover faster. And Ino, she uses her knowledge of plants to find some natural remedies for Naruto's illness. They all come together in their own ways to support Naruto during his time of sickness.
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.
Sakura, being a medic - ninja, would likely be very concerned and immediately start trying to diagnose and treat Naruto. She might be constantly by his side, using her medical skills to ease his symptoms.
His friends would most likely be very worried. They would gather around him, trying to figure out what was wrong. Percy might use his water powers to cool Leo down if he had a fever. Annabeth would be researching in the library, looking for any information on demigod illnesses. Hazel could use her powers to sense if there was any dark magic involved in Leo's sickness.
Well, Betty will be super worried. She's always had a soft spot for Archie. She might skip her own activities to stay by his side, constantly checking his temperature and making sure he's comfortable. Jughead, on the other hand, will try to keep things light. He'll tell Archie stories about the latest strange things he's seen in Riverdale to distract him from his illness. Veronica will be more of the practical one. She'll call in doctors or specialists, using her family's influence to ensure Archie gets the best care possible. All in all, his friends will rally around him.
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.
Sakura, being a medical ninja, would immediately start examining Naruto. She'd be very worried and use all her skills to try and diagnose the illness. Sasuke, on the other hand, might not show his concern openly but would be constantly on edge. He might secretly look for ways to help Naruto get better. Shikamaru would probably start thinking of strategies to keep the village safe while Naruto is sick.
His friends would most likely be very concerned. They would probably bring him things like food and medicine. TK might pray for his quick recovery.
Raven would probably be the first to sense that something was wrong with Beast Boy. She'd be quiet about it at first, but she'd start keeping a closer eye on him. Maybe she'd make him some herbal tea that she believes has healing properties.
His other friends like Shikamaru would think of the most practical solutions. He might calculate the risks of continuing the mission with a sick Naruto and come up with a plan. Maybe he'd suggest splitting the group, with some staying to take care of Naruto and others proceeding with the mission - related tasks that can't be postponed.
The teachers, especially Aizawa, would also be worried. Aizawa might give Bakugou special permission to skip classes or training until he's recovered. He'd also keep an eye on Bakugou's progress and make sure he's taking care of himself.