Perhaps an old member of a forgotten clan who was exiled because of his dark blood. He returns with a vendetta against the village that shunned him. He sees Naruto as a symbol of everything he hates and tries to destroy him. The main antagonist could also manipulate other ninja to turn against Naruto by spreading fear about his dark blood.
In a 'dark blood Naruto fanfic', the dark blood could give the wielder the ability to see the darkest secrets of others. Naruto, with his new power, uncovers a conspiracy within the ninja world that is far more dangerous than anyone thought. He has to use this power, which is feared by many, to save the world while also dealing with those who want to stop him because of his 'dark' ability.
Maybe he discovers some dark secrets in the Blood Prison. These secrets could be about the corruption of the ninja world or some hidden evils related to powerful people. This new knowledge might make him lose faith in the system he once believed in, leading to his transformation into a darker version of himself.
In this type of fanfiction, the plot can be really diverse. It might start with Naruto being sent to the Blood Prison for some false accusations. Once there, he encounters various characters, some of whom are trying to kill him, while others might become his allies. The Blood Prison setting allows for a lot of exploration of Naruto's character in a darker context. It could also involve Naruto having to use his skills in new and creative ways to survive, and perhaps there's a build - up to a big showdown against the main villain or the corrupt forces running the prison.
There are indeed alternatives. Some fanfics might explore the relationships between Naruto and other characters in the Blood Prison context. For example, they could depict how Naruto interacts with the guards or other prisoners in a way that promotes the values of the Naruto universe, such as perseverance, loyalty, and friendship. It's important to avoid the offensive ones and seek out the positive fan - created stories.
He might become more cynical. Instead of seeing the good in people like he used to, he starts to suspect everyone's motives. For example, he may no longer trust his friends easily.
First, re - imagine their backstories. For Naruto, you could focus on how his lonely childhood could have made him bitter instead of hopeful. For Tenten, think about how her lack of spotlight in the original series might have led to envy and a darker path. Then, create a new plot that involves them in morally grey situations.
The main character is Naruto, as it's a Naruto - centered fanfiction. But in the Blood Prison setting, there could be other key characters. For example, the warden of the prison who might be a cruel or mysterious figure. Also, there could be a fellow inmate who has a special connection with Naruto, either as a friend or a rival. These characters play important roles in driving the story forward in the context of the dark and dangerous Blood Prison.
Naruto might also use his blood control to enhance his physical abilities. For example, he could increase the oxygen - carrying capacity of his blood to boost his stamina. Or he could control the blood flow to his muscles to increase their strength momentarily. This would make him an even more formidable opponent in combat, and these applications would make for some really interesting scenarios in the fanfic.
I'm not entirely sure specifically what 'naruto the dark fanfic' is about as there could be many different interpretations. It might be a fan - made story that takes a darker turn on the Naruto plot, perhaps exploring more complex and negative aspects of the Naruto universe like darker character motives or more tragic events.