He could become more determined. If the fanfiction shows immortals achieving great things, Naruto may strive harder to achieve his own goals, thinking that if immortals can do it, so can he. Also, his sense of humor might come into play. He could be making jokes about the strange things in the fanfiction to his friends, but at the same time, be secretly thinking about how some of it could be useful.
Naruto might become more curious. Since he's reading about immortality, a concept quite different from his normal ninja life, he'll want to explore more about such ideas.
Reading the fanfiction could make Naruto more open - minded. He's used to the traditional ninja ways, but this fanfiction about immortality could expose him to new ways of thinking. He may start to question some of the long - held beliefs in the ninja world. For instance, if the fanfiction presents a different view on life and death compared to what he's been taught, he might have to reevaluate his own views. This could lead to some internal conflict at first, but in the long run, it could make him a more well - rounded and adaptable ninja.
His core Naruto - like personality of being determined and never - giving - up would still be there. But he might become more refined and elegant like the elves. He would probably have more patience due to the elven influence. His boisterousness might be toned down a bit, but he would still be the energetic Naruto at heart, just with a more elven - like exterior in terms of behavior.
Naruto's personality might become more calm and centered. Yoda could teach him to control his impulsiveness. So instead of rushing into things, he'd think more before acting.
Naruto might become more secretive. Growing up in the Snake Clan, which is often associated with secrecy and hidden motives, he could pick up on their ways of not revealing too much about himself or his plans. For instance, instead of being as open and brash as in the original series, he would be more guarded in his conversations.
He could become more protective. Since Kiva's powers are powerful, Naruto might feel a greater sense of responsibility to protect his village and friends. He might also be more secretive about his new powers, at least until he fully understands them. And his sense of humor might change a bit, becoming a bit darker or more sarcastic as he gets used to his new identity as someone with Kiva - like abilities.
Naruto's personality might still shine through even as an Arrancar. He's always been determined and kind - hearted. However, he could become a bit more solitary at first as he adjusts to his new form and powers. The Arrancar nature might make him more cautious in some ways, but his basic values of friendship and protecting the weak would remain. He might also develop a bit of an edge, as Arrancars are often seen as more menacing, but it would be a surface change. Deep down, he'd still be the Naruto who wants to bring peace and joy to his village.
Naruto's personality could change in several ways. He has always been determined, but now with the magma - related powers, he might become more assertive. He could also be more protective, seeing his new powers as a way to safeguard his friends and village even more. However, he might also face some inner struggles. The power of the Magu Magu no mi could make him feel different from his comrades, and he might have to deal with feelings of isolation at times.
On the other hand, his abandonment could fuel his determination in a different way. He might be even more driven to prove himself, not just to the village that shunned him as an orphan, but also to himself. He could see his abandonment as a reason to show that he doesn't need anyone's pity or help, and become an even stronger ninja as a result.
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.
Naruto might become a bit more confident and cocky. Shego is often shown as self - assured, and having her powers could make Naruto feel more powerful. He might start showing off a bit more during battles.
Naruto's personality might become more serious. Since Asura Otsutsuki is from an ancient and powerful clan, his influence could make Naruto more aware of the greater responsibilities and the bigger picture in the ninja world.