It could strengthen his relationships. His teammates might be initially wary, but as they see Naruto use explosion alchemy to protect them and complete difficult missions, they grow to trust him even more. For instance, if they are in a battle against a tough opponent and Naruto's new skill saves them, it deepens their bond.
It might change the dynamics completely. Maybe one of his teammates is jealous of Naruto's new ability. This jealousy could lead to friction within the team. On the other hand, another teammate could be inspired by Naruto and try to learn a new skill themselves, creating a more competitive yet positive environment within the team.
With Shikamaru, Naruto's early Rasengan might make Shikamaru more interested in teaming up with him. Shikamaru is smart and he would recognize the potential of having Naruto with his powerful jutsu on their side for missions. So they could form a stronger bond based on mutual respect for each other's abilities.
It could improve his relationship with Sasuke. Since Chidori was Sasuke's signature move for a long time, Naruto learning it might show Sasuke that Naruto respects his skills and is willing to incorporate them into his own fighting style. This could lead to a more positive and equal relationship between them. Also, Kakashi might see Naruto in a new light. He trained Sasuke in Chidori, and seeing Naruto master it too could make him realize Naruto's determination and growth even more.
His relationship with Sasuke could change significantly. Sasuke might see Naruto's newfound ability as a threat or, on the other hand, it could be a motivation for him to get stronger. Naruto might use the Hiraishin no Jutsu to try and keep an eye on Sasuke, which could either annoy Sasuke or make him secretly respect Naruto's determination.
His relationship with Sasuke might become more competitive. Sasuke, seeing Naruto learn such a powerful technique, would strive to become stronger too. This could lead to more intense sparring sessions between them and a bit of friendly rivalry.
In fanfiction, Naruto learning Juken would be an interesting development. Juken is not just about physical strikes but also about chakra control. Naruto has always been working on his chakra control, and learning Juken would be another step in that journey. It could open up new ways for him to interact with other characters. For example, he might be able to use Juken to help heal allies by manipulating their chakra in a different way. Also, it would make his battles more dynamic as he would have an alternative to his regular ninjutsu and taijutsu moves, and his opponents would have to adapt to this new threat.
Well, it would be a huge blow to his friendships. Naruto's friends are drawn to his big heart and strong emotions. An emotionless Naruto would not respond in the same warm way. He might not share in their joys or sorrows. Sakura, for instance, would miss his determination and the way he used to encourage her. His friends would have to work hard to reach out to him, but they may also start to drift apart because the emotional connection is no longer there.
It could make him very distrustful at first. He might have a hard time believing that others truly care about him. For instance, when his friends try to be nice, he might think they have ulterior motives.
Well, his friends would likely be very confused and hurt. They know Naruto as a determined and kind - hearted person. If he's brainwashed, they might initially try to reach out to him, thinking it's just a temporary state. But as time goes on, they could become distrustful if he starts to act against them. Sasuke, for example, might be even more conflicted, seeing Naruto in such a different state. And Sakura would be heartbroken, as Naruto has always been a source of hope and friendship for her.
Well, his friends might start to feel like he's drifting away. Since he's hiding his strength, he can't fully participate in training or battles as they expect. For example, Sakura might think Naruto is being lazy or not trying hard enough, which could create some tension between them.
His malnourishment could make his friends worry more about him. For example, Sakura might start to be more motherly towards Naruto, constantly trying to get him to eat proper meals. His relationship with Sasuke could also change as Sasuke might initially look down on Naruto for being weak because of the malnourishment, but then as he sees Naruto's determination to overcome it, he gains a new respect for him.