Naruto would probably become more serious. Shisui was a serious - minded ninja. His training might make Naruto less impulsive and more calculated in his actions.
His character could change in terms of his view of friendship and loyalty. Shisui was very loyal to his clan and the village. Through his training, Naruto might gain a deeper understanding of what it means to be truly loyal and how to balance different loyalties. He could also become more empathetic towards the Uchiha clan's situation. This would add more depth to his character as he already has a strong sense of justice and friendship. He would be more complex, not just a simple - minded, enthusiastic ninja but also a more thoughtful and understanding one.
Naruto's character would likely become more cynical. Orochimaru's ways are full of deceit and self - gain, and Naruto, being around that, would start to question the ideals he once held. His usually bright and optimistic personality might be clouded with a sense of distrust and a more cut - throat attitude.
Naruto's character would likely become more serious and focused. Training with Shisui and the Sharingan would demand a lot of concentration, so he'd have to tone down his wilder side. He might also become more strategic in combat, as the Sharingan gives insights into opponents' moves.
Naruto would become more cunning. Orochimaru is a very sly character, and his training would likely rub off on Naruto. Naruto would no longer be as straightforward in his battles and interactions. He might start to think several steps ahead, like Orochimaru does.
Naruto would likely become more secretive. Since Orochimaru's training methods are often not in line with Konoha's values, Naruto would have to hide what he's learning. He might also become more distrustful of others as Orochimaru could instill in him the idea that everyone is out to get him for his newfound power.
He'd probably become more adaptable. Naruto is already flexible in combat, but RWBY's diverse combat styles would force him to be even more so. His personality might also become more open - minded as he experiences the different cultures and ways of thinking in the RWBY world.
If Naruto is trained by Deathstroke in fanfiction, his character would change in multiple ways. For one, he might lose some of his naivete. Deathstroke's world is a harsh one, and Naruto would have to adapt. He could become more calculating and less likely to jump into a fight without thinking. His relationships with his friends might also change. He might start to keep them at a bit of a distance, not wanting to put them in danger as a result of his new, more dangerous fighting style.
Naruto's character would become more serious. Sephiroth's training is no joke and Naruto would have to focus more. He might lose some of his naivete and become more worldly.
Naruto's character could change in several ways if trained by Kisame in fanfiction. Firstly, his confidence might take on a different form. Instead of the boisterous and sometimes over - the - top confidence he has, it could become a more subdued and internalized self - assurance. His relationships with his friends in Konoha might also be affected. He might feel a bit of an outsider now that he has been trained by an enemy. Emotionally, he could become more guarded, as Kisame is not one to show much emotion. And in terms of his fighting style, he might adopt a more stealthy and patient approach, which is very different from his usual in - your - face style.
Naruto would likely become more stealthy. Itachi is known for his stealth and if he trains Naruto, Naruto would pick up some of those skills. He might start to rely less on his brash and straightforward fighting style and incorporate more subtlety.
Naruto would likely become more serious. Madara's influence would probably make him less impulsive. For instance, he would think twice before charging into battle without a proper plan.