Yes, there might be such fanfics in the vast Naruto fanfic community. Some fanfic writers like to create alternative scenarios where the characters' identities are swapped or unexpected events like the main character's death occur. These fanfics often explore different aspects of the Naruto universe and the characters within it.
He would be filled with rage. Naruto has a strong sense of justice and the fact that someone took Hinata away from him would fuel his anger. He would vow to find and punish whoever was responsible. He might even become reckless in his pursuit of vengeance, endangering himself and those around him. His friends would have to step in to try and bring him back to his senses.
There could be a scenario where Naruto sacrifices himself to save Boruto or the entire Hidden Leaf Village from a catastrophic event like a massive attack by an unknown and dangerous force. He might use all his chakra to protect the village, leaving him with no energy to survive.
I'm not entirely sure which specific fanfiction this refers to. But if Naruto were to die and become like Kushina, it could be a very interesting concept. Maybe it involves some sort of reincarnation or magic. It could potentially explore Naruto's connection to his mother in a much deeper way, like inheriting her abilities or personality traits. However, without reading the actual fanfiction, it's hard to say exactly what would happen.
I'm not sure specifically as there could be many different versions of such a fanfic. But generally, it might involve Naruto facing some overwhelming danger in the Wave arc that leads to his death, perhaps a more powerful enemy than in the original story or a failed mission that costs him his life.
Fanfictions about Naruto being neglected and nearly dying can be quite intense. Some might depict him being pushed to the brink by the lack of support from the village. For example, he could be deprived of proper training or basic necessities. However, these situations usually lead to Naruto's character growth in a different way than in the original series. He might form unexpected alliances with outcasts or find new powers within himself.
Well, I'm not sure about a single highly recommended one. But in general, in these fanfictions, Naruto's death for Sakura can lead to many different plot developments. It could make Sakura stronger, or it could drive a wedge between her and other characters who might blame her in some way for Naruto's sacrifice.
He would be filled with a deep sense of grief. Naruto has always cared about Hinata, and her death would be like a part of him has been ripped away. He might isolate himself for a while, blaming himself for not being able to protect her. But eventually, he would use his pain as motivation to get stronger and fight against whatever caused her death.
In the Naruto series, Naruto doesn't have a biological sister in the original story. So in this fanfiction, the author probably creates a new character to be his sister. It could be an original character with unique abilities and a complex backstory that leads to the situation where Naruto dies by her hand.
In such a fanfiction, Naruto could die in various ways. Maybe his sister is somehow possessed and attacks him fatally. Or there could be a situation where she accidentally causes his death during a fight due to a lack of control over her power.