Well, in these fanfictions, a major theme is the struggle for power. Naruto's new - found power that makes him feared disrupts the existing power balance in the Naruto world. Another common theme is the fear of the unknown. Since Naruto has something different or extraordinary that makes him feared, the other nations don't know what to expect from him. And there's also the theme of self - discovery for Naruto. As he becomes a figure feared by nations, he has to figure out how to deal with this new identity and the power that comes with it.
Well, in some 'Naruto feared by nations' fanfictions, Naruto could be the sole survivor of a great catastrophe that also gave him an overwhelming power. This power is so great that it makes the other nations fear him as they don't understand it. There are also fanfictions where Naruto discovers a long - lost forbidden art that gives him god - like abilities. As a result, the other nations in the Naruto world see him as a huge threat and fear his every move.
In some fanfictions, Naruto might be feared due to his overwhelming power. For example, if he has some new and extremely dangerous jutsu that others can't understand or counter. It could also be because he has changed his personality to be more cold - blooded and less forgiving, which is a departure from his original kind - hearted self in the official story.
Power - ups are a common theme. Since it combines two powerful universes, the characters often gain new and unique abilities. For example, Naruto might get some devil - like powers in the DxD world.
One common theme is the connection to nature. In these stories, animals often play important roles, representing different qualities or serving as spiritual guides. Another theme is the passing down of cultural values and wisdom from one generation to the next.
One common theme is nature. Since the First Nations have a close relationship with nature, their constellations often represent animals like the bear or the deer. Another theme is guidance. The stars are seen as guides for activities such as hunting and traveling.
One common theme is secrecy. Since the Anbu are a secret organization, the fanfictions often revolve around Naruto having to keep his Anbu life a secret from his friends. Another theme is intense training. As an Anbu, Naruto has to be highly skilled, so his training in these fanfictions is usually very tough and extreme.
Power growth is a common theme. Since Naruto is becoming a sage, the fanfictions usually focus on how his power evolves. For example, in many of them, he has to learn to control new types of chakra as a sage.
One common theme is friendship. Naruto is all about making friends and Eevee can be portrayed as a new friend he makes. Another could be the idea of power. Eevee's potential to evolve into different powerful forms can be linked to Naruto's growth as a ninja.
One common theme is the struggle with identity. Naruto, who is known for his bright and positive nature in the original series, has to come to terms with being an assassin, which is a much darker role. Another theme is secrecy. He has to keep his new identity hidden from his friends and loved ones.
A common theme is the exploration of their father - son relationship. Since Minato died when Naruto was born, fanfictions often delve into what could have been if they had more time together. For example, how Minato would have been as a father figure, guiding Naruto in his ninja training and in life in general.