Naruto would likely be more conflicted. Instead of his usual cheerful self, he'd constantly struggle with the idea of being associated with 'evil'. He might be more withdrawn at first, not sure how to handle this new identity.
A really interesting plot twist could be that the whole concept of 'evil' is a facade. Naruto, as the godson of what is thought to be evil, might find out that Sarutobi was actually in league with this 'evil' all along. They were working together to bring about a new order in the ninja world. But as Naruto grows, he has to decide whether this new order is truly good or just another form of tyranny. He could then use his unique position to either support or oppose Sarutobi and the so - called 'evil'.
In a fanfiction where Naruto is in the Akatsuki, his character would grow in terms of understanding different perspectives. He'd interact with characters who have very different backgrounds and motives from his friends in Konoha. His sense of loyalty would be tested as he'd be in a group that is generally considered the enemy. This could lead to him becoming more independent in his decision - making, rather than relying on the approval of his village. He might also become more calculating, as the Akatsuki often have to plan their moves carefully to avoid detection and achieve their goals.
His relationships with his peers would be different. For example, if he was adopted into a well - respected shinobi family, some characters who looked down on him before might treat him with more respect, and this would impact how he interacts with them. He might be less likely to seek attention through pranks.
In this kind of fanfic, Naruto's character development would be significant. Initially, he'd be full of anger and resentment towards Sarutobi and Konoha. But as he faces the challenges of the outside world, he realizes that there are bigger issues at play. His experience outside the village would make him more empathetic towards those who are also ostracized. He'd become a more well - rounded character, not just a loud - mouthed ninja from Konoha. His relationships with others would change too. He'd form deeper bonds with those who accept him during his exile, and these relationships would shape his future actions and decisions. He might also start to question the whole ninja system, which could lead to him trying to change it when he has the chance to return to Konoha.
Naruto would likely be more confident. With Sarutobi as his adopted father, he would have a strong support system. He might not be as brash as in the original story, as Sarutobi's teachings would instill more discipline in him.
Naruto would become more disciplined. Sarutobi is a strict teacher, so Naruto would have to follow rules more closely. This would make him less impulsive in battle.
Naruto's character might become more conflicted. His usual positive and straightforward view of the world could be challenged. He might start to question his own ninja way more often, as Pein's extreme methods would force him to re - evaluate his beliefs about how to achieve peace.
He might be more mature earlier. Since he would have more time to experience life in the village, he could be less impulsive. For instance, he might not pull as many pranks as in the original story.
Naruto's character might develop a more diplomatic side. The Senju were often involved in negotiations and maintaining peace. So, he could be more inclined to talk things out rather than jump into battle right away. He would still have his energetic and determined side, but with a touch of Senju wisdom. For example, when dealing with other villages or clans, he would use his Senju heritage to build bridges and find common ground rather than just relying on his strength as a ninja.
Suppose the teacher was from a different culture within the Naruto world. Naruto would be exposed to new values and ways of thinking. He might become more empathetic towards other cultures and incorporate elements of that culture into his ninja way. This could make him a more well - rounded and diplomatic shinobi in addition to being stronger in combat.