Maybe the shapeshifting power is a result of a forbidden jutsu that was sealed away long ago. As Naruto uses it more, he starts to unlock memories from the past that change his perception of the ninja world. For example, he could discover that the so - called 'evil' ninja in history were actually victims of a greater conspiracy. This would completely change his view on what it means to be a ninja and how he should use his powers.
A possible plot twist is that Naruto's new dark powers attract a group of powerful dark - sided ninjas who want to use him as a weapon. But Naruto resists and has to find a way to get rid of these powers without losing his life or his identity. He might also learn that there is a hidden, positive side to these dark powers that can be harnessed for good if he can overcome the initial darkness associated with them.
I haven't read this specific fanfiction yet. But generally, in a Naruto fanfiction with a 'Shapeshifting Master of Darkness' concept, it could explore Naruto having new and dark powers. Maybe he can transform into powerful and shadowy forms to fight enemies. It might also involve a new, darker side of the Naruto universe.
One possible plot twist could be that Naruto's control over light and darkness is initially seen as a great power, but it actually comes with a hidden curse. For example, every time he uses it too much, he starts to lose his memories related to his friends and his village. This would add a great deal of internal conflict for Naruto as he has to balance using his power to protect those he loves while also not losing his connection to them.
Maybe Naruto has the ability to deceive even the all - seeing Sage Mode. He could use this to his advantage during battles or important diplomatic meetings. For example, he could make enemies believe he is in a much weaker state than he actually is, only to turn the tables when they least expect it. This would add a whole new layer of strategy to his character.
Maybe Naruto discovers a dark secret about his family or the village's origin that shatters his beliefs. For instance, if he finds out that his father was involved in something immoral and the village covered it up. This realization could make him feel betrayed and start to embrace darker powers in his anger and confusion. He might then use these powers to take revenge or to change the village in a more forceful and less benevolent way.
In 'naruto controls the darkness' fanfiction, it could also be that Naruto is exposed to a dark energy source accidentally. This energy starts to influence his thoughts and actions in negative ways at first. But being Naruto, he doesn't give in. He uses his strong willpower and the positive relationships he has with his friends like Sasuke, Sakura, and others to find a way to control this new dark power. He might have to face some of his own demons from his past, like the loneliness he felt as a child or the times he failed to protect his friends, and use these experiences to better understand and control the darkness within him.
The plot might involve Naruto exploring the darker aspects of his world. Maybe he discovers a hidden organization within Konoha that has been dabbling in dark jutsu. This could lead to him having to make difficult choices between loyalty to his village and uncovering the truth.
In a 'naruto controls darkness fanfiction', perhaps Naruto initially struggles with this new power. He's a hero associated with light and positive energy, so controlling darkness could be seen as a corruption. But then he realizes he can use it for good, like infiltrating dark organizations by blending in with their dark - themed jutsus.
One common plot twist is the discovery of a new and powerful ninjutsu that changes the power dynamics. For example, Naruto might find a long - lost ninjutsu that gives him an edge over his enemies. Another twist could be a character turning out to be a traitor. Maybe someone Naruto trusted all along is actually working for the enemy. And sometimes, there's a twist where a character's ninjutsu has an unexpected side effect that they have to deal with.
The plot might center around Harry being the master of darkness as a way to subvert the prophecy. Instead of being the 'Chosen One' in the typical light - against - dark way, he uses the knowledge of the dark arts to understand and outwit Voldemort. He could be learning long - forgotten spells from the darkest corners of Hogwarts library and using them to his advantage.
In a Naruto is Vergil fanfiction, it could be that Naruto's connection to Vergil is through a dream - like realm. Every time Naruto sleeps, he enters a world where he meets Vergil and learns from him. Over time, Naruto starts to incorporate Vergil's values into his own. He becomes more focused on power for the sake of protecting those he loves in a more 'Vergil - esque' way, which means he might be willing to make some sacrifices that he wouldn't have considered before, like sacrificing some of his own personal relationships for the greater good of the village.