One possible reason could be that his sisters have some special abilities or qualities that overshadow Naruto in his family's eyes. Maybe they are prodigies in ninja skills from a young age, and the family focuses all their attention on them. Another reason might be that Naruto has some sort of accident or incident in his childhood that makes the family see him as a disappointment, so they start to neglect him.
Perhaps the family blames Naruto for something that isn't really his fault. Maybe there was an attack on the family, and Naruto was the only one present at the time, even though he was too young to do anything. The family, in their grief and confusion, wrongly holds Naruto responsible and starts to neglect him. Or it could be that Naruto has a different personality from his family. His more rambunctious and independent nature might not be liked by his family who prefer more docile and traditional behavior like his sisters, leading to his neglect.
It could also be due to some family curse or prophecy. In the Naruto universe, there are often strange powers and curses. Maybe there was a prophecy that said Naruto's family had to keep their distance from him to protect him from some greater evil. So, they chose to neglect him in order to keep him safe, even if it was a difficult choice.
Maybe there are secrets in the family. For example, his parents might be involved in some dangerous and secretive missions that require them to keep their distance from Naruto to protect him, but Naruto misinterprets it as neglect.
One possible reason could be jealousy. If Naruto has the rare Mokuton ability, his family might be jealous of his potential power and neglect him out of spite.
One possible reason could be that they are too focused on their own problems or duties. Maybe they are involved in some important shinobi business that takes up all their time and attention, causing them to overlook Naruto.
One reason could be that his siblings have some special abilities or talents that overshadow Naruto. In the ninja world, those with unique powers often get more attention. So, if his siblings possess something extraordinary, Naruto might be pushed to the side.
In Naruto fanfiction, family neglect can be shown in various ways. For example, Naruto's own upbringing was filled with neglect as he was shunned by the villagers. Fanfictions might expand on this by having his family, if they were alive, also be cold or distant. It could be that his parents, if alive, were too caught up in their shinobi duties to give him proper attention.
One possible reason could be that they are too involved in their own shinobi duties. The world of ninjas is full of dangerous missions, and they might be constantly away on important tasks, leaving Naruto feeling neglected.
For Naruto, the consequence of family neglect in fanfiction could be a deep - seated loneliness. He might have trust issues, always doubting if people really care about him or just using him. It can also make him more reckless in battle, as he doesn't have that family support system to hold him back from taking unnecessary risks.
Well, Percy is often neglected in fanfiction because he doesn't have the same kind of popularity as the main characters. In the books, he's not part of the core group that goes on the big adventures. He's more into the rules and regulations of the wizarding world. Fanfic writers usually prefer to write about characters who are more involved in the action - like Harry facing Voldemort. Percy's role in the official story is more of a background one in terms of the main plot, so it's easier for him to be overlooked in fan - created stories.
One possible reason could be his own missions and responsibilities. Jiraiya is often away on important spy missions or gathering information for the Hidden Leaf. He might be so caught up in these tasks that he unintentionally neglects Naruto.