Naruto's personality would experience a significant shift. Darth Vader is a very serious and often dark character. His training would likely make Naruto less impulsive. Naruto might become more reserved and calculating, as he would be exposed to Vader's strategic way of thinking. However, his core values of protecting his friends and his village might still remain, but they could be expressed in a more guarded manner. He may also develop a sense of isolation like Vader, as the training might set him apart from his peers who wouldn't understand his newfound knowledge and power.
His personality might become more brooding. With Darth Vader's influence, Naruto could lose some of his naivete and become more cautious.
His personality could become darker. Darth Vader's influence might make Naruto more brooding and less of the optimistic character he is. He could start to value power more than friendship at times.
His personality would likely become more brooding. Darth Vader's influence might make Harry more withdrawn as he grapples with the new and often dark teachings. He may lose some of his innocence and optimism.
Naruto could become more intimidating. His natural exuberance would be tempered by the imposing nature of Darth Vader's suit. However, he'd probably find a way to still show his kind heart. Maybe he'd use the suit to scare off enemies at first, but then when they least expect it, show his true Naruto self and offer them a chance to change. He'd have to balance the new - found power of the suit's appearance with his own desire to be a hero in his own way.
Naruto's personality would be a complex mix. On one hand, he might become more reserved due to Vader's influence. But on the other hand, his natural inclination towards goodness might cause him to constantly struggle against Vader's darker teachings. He could be a much more conflicted individual, with his usually open - hearted and friendly personality warped by the dark environment he was raised in. He might be more secretive and less trusting of others as well.
Well, Naruto would probably become extremely powerful. Darth Vader's skills in the Force and his combat expertise could be combined with Naruto's chakra powers. Naruto might learn new ways of fighting and gain a darker edge to his character.
Well, Naruto would probably become an extremely powerful ninja with some very unique skills. Darth Vader's training might introduce him to the dark side of the Force, which could be translated into some sort of dark chakra manipulation in the Naruto universe. This could make Naruto's attacks more menacing and unpredictable.
Naruto might become more sly. Since Loki is a trickster, Naruto could pick up some of his devious ways. He may not be as straightforward as he used to be.
His personality might change in several ways. He would probably be more humble as he realizes the vastness of the power he is being exposed to. Also, he could become more of a mentor - like figure to the younger ninjas in Konoha. Since he is getting trained by such a powerful entity, he would have a greater sense of responsibility and would want to pass on his knowledge. He might also become more open - minded, as the Grand Priest's teachings could expose him to new ways of thinking and different cultures if the fanfiction has elements of different universes interacting.
If trained by Darth Vader, Naruto and Hinata's relationship could change in many ways. The shared experience of Vader's intense training would bond them. Naruto might see Hinata in a new light as she adapts to Vader's methods. Hinata could also grow more confident around Naruto. However, there could also be some tension as they both strive to meet Vader's high standards and compete for his approval, but overall, it could lead to a more mature and interdependent relationship.
He might become more cautious. Tsunade is a more calculating ninja compared to some of Naruto's previous mentors. So Naruto could start to think before he leaps, rather than just charging into battle head - first all the time.