A possible plot is that Naruto is constantly bullied because of his neglected state and his unknown bloodline. As he grows, he starts to show signs of his bloodline powers, which attracts the attention of both friends and foes. His journey then becomes about controlling his powers and dealing with the past neglect of his parents while also facing the new challenges that come with his revealed bloodline.
The angel bloodline might be neglected in the fanfiction due to the lack of connection to the existing Naruto lore. In the Naruto world, there are already established power systems and lineages. If the angel bloodline is not carefully tied to these existing elements, it may be pushed to the side. Additionally, the writer might be saving it for a big reveal later in the story, so it appears neglected in the early parts.
One possible story could be that Naruto discovers his unique bloodline abilities later in life and realizes that his parents' neglect was partly due to fearing his power. He then has to come to terms with this and learn to control his abilities on his own.
In fanfiction, Naruto having the Rinnegan and being neglected by parents can lead to some really interesting character development. It could make him more self - reliant and distrustful at first. He might have to learn to harness the power of the Rinnegan on his own, without any parental guidance. This could result in him making some mistakes along the way but also growing stronger in unique ways.
One possible reason could be that the author wants to focus on Naruto's growth through his own hard work and determination rather than relying on his bloodline. It adds more drama and makes his achievements seem more earned.
One possible scenario in such a fanfiction could be that Naruto's parents are preoccupied with their shinobi duties. They might be constantly on missions for the Hidden Leaf Village, leaving Naruto at home with caretakers who don't really pay him much attention. This could lead to Naruto feeling lonely and isolated, just as he did in the original story when he thought he had no family.
Another possible ability could be purification. The angel bloodline might be able to purify corrupted chakra or evil spirits. In the Naruto universe, there are many instances of dark forces and cursed chakra. A character with this bloodline could be the key to cleansing such malevolent entities. For example, they could purify a village that has been infected by a dark curse or a powerful demon's influence.
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.
One plot twist could be that Naruto discovers his parents had a very good reason for their neglect, like they were protecting him from a greater danger. Another could be that the village elders knew about the neglect but did nothing, and Naruto has to confront them. Or perhaps Naruto finds out he has a secret power that was the cause of his parents' seeming neglect, as they were afraid of what he could do.
One way could be through a sudden discovery during a dangerous mission. Maybe he gets injured and his body's natural response activates some latent aspect of his bloodline.