He might need to find a powerful ninja who can repair or reinforce the seal. For instance, someone like Jiraiya or Tsunade could potentially help.
Naruto could survive a damaged seal in a fanfic by relying on his own willpower. He has a strong spirit and has overcome many difficulties before. He could try to suppress the Nine - Tails' chakra on his own while seeking help. Also, he might discover some hidden power or technique within himself that can counteract the negative effects of the damaged seal.
In a fanfic, if Naruto's seal gets damaged, he might lose control over the Nine - Tails' power. This could lead to sudden and uncontrollable outbursts of chakra. For example, he could accidentally harm his friends or destroy the surrounding area during a fight.
It's also possible that Naruto uses his strong willpower. We know Naruto has an unbreakable spirit. He could use that determination to resist the effects of the seal until it eventually breaks. He might enter a state of deep meditation or concentration and focus his chakra in a way that overpowers the seal.
Well, these fanfics can explore character development by delving into Naruto's past traumas. Say he was bullied as a child in the fanfic. As he faces these old emotional wounds, he could learn to forgive or find new ways to interact with others. It might also make him more cautious or more open - minded depending on how he deals with it. This all shows his development as a character.
Harry could try to communicate with the entities in the seal. By making allies, they might help him survive. For example, if he befriends a chakra - based spirit, it could guide him on how to get the resources he needs, like food (in a spiritual sense perhaps) or a safe place to stay within the seal.
Kakashi could also be of assistance. With his Sharingan, he might be able to analyze the seal and figure out its weak points. Then he could guide Naruto on how to target those weak points and break the seal.
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.
His character would likely become more complex. With the Sharinegan, he'd have to deal with new responsibilities and a different kind of power. He might become more introspective as he tries to understand the origin and purpose of this new ability.
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.
At first, Naruto is likely to be confused and hurt. He has always considered the Leaf village his home and the villagers his family, so being banished would be a huge shock. He might feel betrayed.