There might be a fanfiction where Naruto's feeling of being neglected makes him question the values of the ninja world. In this 'evil Naruto' scenario, he could start to target the shinobi system itself. He would use his intelligence and combat skills, which he developed despite the neglect, to expose the flaws in the system. For example, he might target the way the villages treat their jinchuriki. His actions would be seen as 'evil' by those in power, but to some, he could be a revolutionary trying to change a broken system.
In fanfiction, the 'evil Naruto neglected' concept often starts with Naruto being overlooked or mistreated in Konoha. This neglect can be emotional, like not getting the support he needs, or physical, such as not getting proper training. This then causes a shift in his character. He becomes disillusioned with the village and its values. His anger and resentment build up, and he starts to act out in ways that are considered 'evil' by the standards of the ninja world. For example, he might use his powers to get revenge on those who wronged him.
In such fanfictions, it often creates a dark and complex storyline. Naruto's 'evil' turn could be a result of the neglect. This can lead to him seeking power in different ways, perhaps even turning against the village. It might also make for some interesting character development as he battles his inner demons while facing the outside world that once shunned him.
Well, one possible interesting plot could be the exploration of a darker Naruto who has been pushed to the edge by neglect. Maybe he forms unexpected alliances with characters usually considered antagonists in the original story, like Orochimaru, but for different motives than in the canon. He might be seeking power not just for himself, but to expose the flaws in the ninja system that led to his neglect.
The villagers themselves could be the main antagonists. Since Naruto has been neglected, their continued mistrust and hostility towards him could drive his 'evil' turn. They represent the status quo that has failed Naruto, and he might see them as the source of his problems.
One common theme is isolation. Naruto feels alone due to his family's neglect, which pushes him towards evil. Another is revenge. He may seek to get back at those who ignored him or his family. Power - hunger is also often seen as he tries to gain strength to prove himself, since his family didn't give him the love and support he needed.
Perhaps he's been influenced by someone who gives him bad advice. For example, if someone tells him that natural talent is enough and training is overrated. Also, he could be dealing with some personal problems, like a conflict within his family or among his friends that takes up all his time and mental energy, causing him to neglect training.
He might start to rely on his friends more. For example, Sasuke and Sakura could become his main source of emotional support. He would focus on training with them and sharing his feelings, which in turn helps him to grow stronger and more independent.
In Naruto, the Jinchuuriki were often treated poorly. In fanfiction, this neglect can be explored in many ways. One common approach is to focus on the emotional and psychological impact on the Jinchuuriki. For example, they might feel isolated from the rest of the village due to the fear and prejudice associated with the tailed beasts within them. This can lead to some really interesting character development stories in fanfiction.
In a fanfiction, perhaps neglected Naruto runs away from Konoha and ends up in the same area as Yugito. Yugito, having also faced her own share of hardships, takes Naruto under her wing. They bond over their experiences, and Yugito helps Naruto to better understand his chakra nature by sharing her knowledge of the tailed beasts' chakra. This could lead to Naruto developing new abilities and a newfound confidence.