In these types of fanfics, a theme could be the loss of hope. The usually optimistic Naruto world is turned on its head, and Naruto himself might experience a loss of the hope that was so characteristic of him. This could lead to a more nihilistic view of the world within the fanfic, with characters having to grapple with a much darker reality than in the original story.
Often, in such a 'naruto goes very dark fanfic', a possible theme is the corruption of power. Naruto could be depicted as being influenced by power in a negative way, leading to a downward spiral in his character. Also, the theme of betrayal might be present, where friends turn on each other in this darker version of the story.
One common theme is betrayal. For example, Naruto might feel betrayed by the village or his friends, which leads him to go dark. Another theme is power corruption. If Naruto gains too much power too quickly, it could corrupt him and send him down a dark path.
It could be an evil version of Sasuke. In the original story, Sasuke had his dark moments, and in a very dark fanfic, he could be fully consumed by evil and oppose Naruto in a much more malevolent way.
A frequent theme is the struggle against a common dark enemy. In these fanfics, Naruto and Sasuke may put aside their differences in a much darker and more dangerous world. They have to rely on each other's skills, which are also often enhanced or altered in the dark fanfic scenario. This can lead to some intense battle scenes and moments of grudging respect between them. Also, the theme of redemption might be there. Even if they have fallen into dark paths, they might seek a way back to the light through their bond.
One common theme could be the struggle with inner darkness. Naruto might be facing his own demons or a darker side of his power, much like the idea of a 'battousai' who has a more violent and uncontrolled aspect. Another theme could be isolation. As he delves into the darker parts of his character, he may find himself isolated from his friends and the village.
Common themes in 'naruto the dark night fanfic' include secrecy. The night provides a cover for secrets, and Naruto could be uncovering secrets about his friends, enemies or the village. There's also the theme of struggle. The night can make it harder for Naruto to fight or make decisions. And finally, there's the theme of the power of the night. It can be a source of power for Naruto or his enemies, which creates an interesting dynamic in the fanfic.
Power corruption is a common theme. Since Naruto has godlike powers in these fics, there's often a struggle with how much power he should use and whether it changes him for the worse.
One common theme is self - discovery. Naruto might be exploring his more feminine side as part of understanding himself better. For instance, he could be realizing that having feminine traits like being nurturing doesn't make him any less of a strong shinobi.
One popular 'naruto goes dark fanfic' is 'The Darkening of Naruto'. It shows Naruto taking a more cynical path due to the harsh treatment he received in the village. Another could be 'Naruto's Shadowed Path' where he is influenced by dark forces and his personality changes drastically.
Power is a common theme. Since Naruto is 'dark godlike', power dynamics play a big role. Also, love and relationships within the harem are common. Each girl in the harem has a different kind of relationship with Naruto, be it based on admiration, friendship turned into love, etc.
Well, often there's the theme of conflict. Given that Indra has his own set of beliefs and Naruto, even in his 'dark' form, would have his own. There could be an internal struggle within Dark Naruto about whether to follow Indra's path completely or carve out his own. Family also can be a theme. Naruto's family has always been important, and in a fanfic with Indra involved, it could be about how Indra's influence either affects Naruto's relationship with his family or how Naruto's family tries to bring him back from his 'dark' state. And of course, friendship. Maybe Dark Naruto meets new allies or has a strained relationship with his old friends, all while Indra's influence looms in the background.