It could be members of the Akatsuki. Despite being antagonists in the original series, in the fanfiction they might have a change of heart. Maybe Pain, after seeing Naruto's resolve, decides to become his friend. Or it could be Orochimaru's former subordinates who see a different path through Naruto.
Well, without friends, Naruto might become more self - reliant. He'd have to rely solely on himself for training and getting stronger. He might also grow to be more reserved as he doesn't have friends to share his thoughts and feelings with. This could make him more of a lone wolf type, focusing only on his goals like becoming Hokage without the distractions or support of comrades.
One possible plotline could be Naruto becoming a sort of outcast ninja. He would focus all his energy on solo missions and self - improvement, perhaps trying to prove to the village that he doesn't need friends to be a great ninja. Another could be that he gets involved in a darker side of the ninja world, as without friends to keep him on the right path, he might be more vulnerable to negative influences.
Sasuke would likely be a bit more reserved in his reaction. He might see the cybernetics as a potential advantage for Naruto but also as a sign of Naruto relying too much on technology rather than his own natural skills. However, if he saw that the cybernetics made Naruto stronger and more capable of fighting their common enemies, he would probably come to accept it over time.
Well, it could be about Naruto befriending characters from the so - called 'other side' which might be enemies at first. For example, he could make friends with some of the rogue ninjas. They might start by having a common goal, like protecting a certain village from a greater threat. And through that shared experience, they form an unlikely bond.
If Naruto has leukemia in a fanfiction, his friends' reactions would be complex. For example, Kiba might be angry at the situation, feeling that it's unfair to Naruto. He would try to find ways to make Naruto feel better, like taking him on walks with Akamaru. Rock Lee would be inspired by Naruto's fight against the disease, seeing it as another form of training. Tenten would help by getting any items or herbs that might be useful for Naruto's treatment. And all of them together would form a strong support network for Naruto, constantly reminding him that he's not alone in this fight.
Sakura might be initially suspicious. She is a smart girl and would wonder about the butler's intentions. She might keep a close eye on him to make sure he doesn't harm Naruto in any way.
His friends like Shikamaru would likely find the whole situation tiresome at first. He'd be thinking 'What a drag, now we have to deal with Naruto and his pacifier.' But then he might start to see the humor in it and use it as a way to tease Naruto in a friendly way. Choji would probably be more sympathetic and offer Naruto some snacks to go with his pacifier, seeing it as something that makes Naruto a bit more vulnerable and in need of comfort.
Sakura would probably be the first to jump into action. As a medical ninja, she'd immediately start examining Naruto and try to figure out the cause of the fever. She might be worried but also very focused on treating him.
Sakura would likely be very concerned. She's a medical ninja, so she'd first check Naruto's physical condition to make sure there's no underlying medical issue causing the panic attack. Then, she'd try to calm him down by speaking softly and reassuringly, reminding him of all the times he's overcome difficulties.