To make a 'Naruto takes life' fanfic unique, you could set it in an alternate universe. For example, a world where the ninja code is different and taking life is more common or even expected in certain situations. Naruto would then have to navigate this new moral landscape.
You could make it unique by focusing on the emotional and psychological impact on Naruto in a very different way. Instead of the typical guilt, maybe he becomes numb to it at first and then slowly realizes the true weight of what he's done later on. This would be a different take on the common theme.
Another way to make it unique is to involve other characters in a more in - depth way. For instance, Sasuke could be the one who has to deal with Naruto taking a life, and their relationship could be strained or transformed in unexpected ways. It could also explore how the village as a whole reacts to Naruto's actions, not just Naruto's own internal struggle.
One way to make it unique is to give a different backstory to their relationship. For example, what if they had a childhood encounter that they both forgot but subconsciously affects their feelings now? In terms of the 'lemon' aspect, instead of the common physical intimacy, it could be more about the emotional and mental connection that is so intense it feels like a physical attraction. And for the overall story, involve some unexpected characters. Maybe Tenten has a role to play in bringing them together or creating some misunderstandings that add drama to the story.
You can make a Naruto noose fanfiction unique by changing the context of the noose. Instead of it being a normal noose, make it a noose made of chakra strings. This gives it a Naruto - like twist.
To make it unique, you could give Goku some of Sakura's characteristics and vice versa. For example, Goku could be more in touch with his emotions like Sakura, or Sakura could have Goku's love for fighting and food. This role - reversal of sorts can add a fresh twist.
To make a Naruto gender - swap fanfiction unique, you can change the character dynamics. For example, if Naruto is female, how does that change her relationship with Kakashi? Maybe Kakashi is more protective or has different training methods for her. Also, you can focus on different aspects of the ninja world that were not explored as much in the original. Such as the role of female ninjas in different clans.
A bullied Tony Stark fanfic can be made unique by exploring different aspects of his character. Maybe he has a hidden talent that the bullies accidentally bring out. Or you could make the fanfic a period piece, set it in the past or future in a very distinct way. For example, in a steampunk - like world where his technology is a mix of old - fashioned gears and advanced science. Also, the way the bullying is resolved can be unique. Instead of him using his tech to fight back, he could use his charm and wit to outsmart the bullies and turn them into his friends.
Use an unusual setting. For example, set it in a post - apocalyptic world where Britney Spears has to use handcuffs as a tool for survival, like handcuffing a raider to a pole to keep her safe. This would be very different from typical fanfic settings.
To make it unique, you could also play with the time period. Set the fanfic in an alternate timeline where Gotham is a more magical place. Baby Robin could have some sort of latent magical ability that he's not aware of, and Batman has to figure out how to deal with this new aspect while also protecting Robin from those who might want to use his power for evil. This would add an element of mystery and the supernatural to the fanfic.
A 'naruto blind fanfic' can be unique by changing the power dynamics. Since Naruto is blind, his usual combat style relying on visual cues has to change. Maybe he becomes a master of genjutsu that affects the opponent's other senses instead of sight.
A 'naruto scars fanfic' can be unique by giving the scar a special power. For instance, the scar could be the key to unlocking a hidden jutsu or a connection to a long - lost clan. This would set it apart from typical fanfics.
To make it unique, focus on the power dynamics between them. Maybe the female shinigami has powers that Naruto doesn't understand at first, and he has to learn to work with her in a different way. And instead of a typical love - at - first - sight scenario, have their relationship develop slowly over many adventures. Have them argue and disagree on things like how to handle enemies, and then gradually come to understand and respect each other's viewpoints, which then leads to a deeper and more unique form of love.