Other ninja from different villages would be quite curious. They might not understand the relationship between Gaara and Naruto at first. Some might see it as a weakness in Naruto, that he needs someone to protect him so much. But as they get to know more, they could come to respect the bond. For example, Neji might initially be skeptical, but after seeing how it actually helps Naruto in some ways, he could change his view. And characters like Shikamaru would just find the whole situation a bit of a headache, as it adds another layer of complexity to the group dynamics.
Sakura might be a bit annoyed at first. She's used to Naruto being independent and always charging forward, and Gaara's overprotectiveness could seem like it's getting in the way. Kakashi, on the other hand, would probably be more understanding. He'd see the value in Naruto having someone looking out for him, but he might also try to encourage Gaara to let Naruto grow on his own a bit. Sasuke could have a very negative reaction. He might see it as Gaara trying to steal Naruto away from him in a sense, especially if he has his own unresolved feelings towards Naruto.
Maybe it's because Gaara sees a lot of himself in Naruto. They both had difficult pasts and were kind of loners at first. Gaara wants to protect Naruto from the pain he once endured.
Well, it could change the storyline in many ways. For one, Naruto would have an even stronger support system. Gaara, being overprotective, might prevent Naruto from getting into some of the more dangerous situations he usually jumps into. This could potentially slow down Naruto's growth in terms of combat experience as he'd be shielded from some threats. But on the other hand, it could also give Naruto more emotional stability, which could in turn help him better control his chakra and learn new jutsus faster. Gaara's presence as an overprotective brother could also affect how the other characters interact with Naruto. Some might be more cautious around him because they know Gaara is watching over him like a hawk.
Sakura might be worried about Naruto. She could try to comfort him and encourage him not to give up. She might also be angry at Jiraiya for abandoning Naruto, seeing how much Naruto has been through already. Kakashi, on the other hand, would probably step in more as a mentor. He has his own way of teaching, and he'd want to make sure Naruto doesn't go astray.
Hinata would be heartbroken. She loves Naruto deeply. Her world would shatter. She might try to find out the truth behind his death, not believing that his friends could do such a thing without a good reason. And she would probably hold a grudge against those involved.
One possible plotline could be Naruto protecting his younger sibling from the threats of rogue ninjas. He would use his skills and influence in the ninja world to keep them safe, perhaps even training them secretly to ensure they can defend themselves. Another plotline might involve Naruto dealing with a political situation where his sibling is in danger due to their relation to him. He has to navigate the complex world of ninja politics to safeguard his family.
He might start to compare the fanfiction world too much with the real Naruto story, which could lead to some confusion. For example, if a fanfiction has a completely different view of a character's personality, he may struggle to separate it from the original.
One situation could be in battle. Gaara might shield Naruto from incoming attacks, using his sand powers without hesitation. For example, if an enemy ninja throws a powerful jutsu at Naruto, Gaara quickly forms a sand barrier around him to protect him.
For the other shinobi in the Hidden Leaf Village, Gaara's protectiveness towards Naruto could change their perception of Gaara. They might start to trust him more and see him as an ally rather than just a former enemy. This could lead to more cooperation between the Sand Village and the Leaf Village. For the younger generation of shinobi, like Boruto and his friends, they could look up to Gaara as an example of loyalty and brotherhood. Gaara's actions towards Naruto could inspire them to be more protective of their own friends and comrades.
His overprotectiveness towards his sibling might make his friends a bit cautious. They might not want to involve Naruto's sibling in any dangerous missions or activities for fear of angering Naruto. For example, Kakashi might be more hesitant to let Naruto's sibling go on a mission with the team.
Many characters would have interesting reactions. Tsunade would likely see it as an opportunity for Naruto to grow and diversify his skills. She might allocate some resources for his sword training. Jiraiya, if he were still alive, would probably be proud and see it as another step in Naruto's journey to become a great ninja. Gaara might view it as a sign of Naruto's ever - expanding power and be even more determined to keep up with him in terms of strength. And the Akatsuki members, if they knew, would probably start to re - evaluate Naruto as a more serious threat now that he has a new and dangerous weapon at his disposal.