Naruto's character would transform in multiple ways. Firstly, he'd be more of an enigma to others. His ability to eat souls would set him apart. He'd have to grapple with the moral implications, which could make him more introspective. Joining the Mist would expose him to different values and fighting styles. He might become more stealthy and calculating, adapting to the Mist's ninja culture. At the same time, he might struggle to hold on to his original values of friendship and loyalty, constantly at war with the dark side that his soul - eating ability represents.
His character would change drastically. He'd no longer be the pure - hearted ninja we know. The act of eating souls might make him more power - hungry. In the Mist Village, he could be influenced by their more cut - throat ways. He might start to see the world in a more cynical light, using his power for personal gain rather than for the good of others like he used to.
He might become more secretive. Naruto is usually an open - book, but in the mafia, he'd have to hide his intentions and actions. So he'd develop a more guarded personality.
Naruto may become more serious and stealthy. ANBU work requires a certain level of secrecy and discipline, which could tone down his usual exuberant personality.
Well, it could be about a dark version of Naruto having the power or the need to consume souls. Maybe it's a twisted take on his character where he's no longer the hero we know, but a being driven by some dark force to feed on souls for power or survival.
Perhaps in the 'naruto eats souls fanfiction', Naruto is cursed by an evil force. This curse makes him uncontrollably eat souls. He then has to struggle to find a way to break the curse while dealing with the consequences of having eaten souls, like the anger of the spirits' friends or families.
His character could change in several ways. Firstly, he'd likely become more stealthy. In the ANBU, being able to move without being detected is crucial. Also, he might become more cynical. The ANBU deals with some dark stuff, and that could make Naruto question the world around him more. He may still hold onto his core values of protecting his friends and the village, but he'd view things from a more jaded perspective. He'd also have to be more calculating in his actions, thinking several steps ahead like the other ANBU members.
His character could become more stealthy. Since the Hidden Mist Village is known for its assassins, Naruto might pick up some of their skills and become more proficient in covert operations. This would add a new dimension to his fighting style.
The power dynamics could shift. In fanfiction, new powers could be introduced to Naruto, making him even more powerful. This would change how he is perceived in the Naruto universe and how he interacts with other characters like Sasuke and Sakura.
Obviously Naruto himself would be a main character, in his dark form. There might also be other characters like Sasuke. Sasuke might be in a position of either trying to stop Naruto or joining him in his dark deeds. And Sakura could also be there, perhaps as a voice of reason trying to bring Naruto back from the darkness.
It could be a powerful spirit that is enraged by Naruto's soul - eating. This spirit might have been protecting the souls in the first place and now sees Naruto as a great threat.
One possibility is that Naruto could bring a new sense of unity to Mist Village. His never - give - up attitude and ability to make friends might inspire the shinobi there. He could also learn unique Mist Village jutsu and combine them with his own skills, creating new and powerful fighting styles.