Well, it depends on the specific fanfiction. There are numerous fanfictions out there with different interpretations of Naruto. Some might focus on his regular ninja skills and not turn him into a super soldier, but in others, he could be given super - strength, super - speed, and other qualities typical of a super soldier to make for an interesting and unique story.
One main theme is loyalty. Just like in the original Naruto series, in 'naruto soldier fanfic', the characters, especially those in the role of soldiers, show loyalty to their village, comrades, and leaders. For example, Naruto might be depicted as a soldier who would do anything to protect Konoha.
His speed is another characteristic. Naruto could move at blinding speeds, making it almost impossible for opponents to track him. In some fanfictions, he can zip around the battlefield so fast that he appears as a blur, dodging attacks effortlessly and launching his own counterattacks in an instant.
In this fanfiction, Naruto might have the same kind of combat skills as the Winter Soldier. He could be stealthy and efficient in combat, using his ninja skills in new and unexpected ways. For example, his shadow clones could be used to create distractions like the Winter Soldier's misdirection tactics. And his journey to break free from the control that has been imposed on him would be an interesting plot point.
One common theme is transformation. Naruto often transforms from a regular ninja into a more disciplined soldier, which brings about changes in his behavior and relationships. Another theme is loyalty, as he has to show loyalty to his new military - like group.
One interesting 'Naruto Soldier' fanfiction could be about a new type of ninja soldier created in the Naruto universe with unique powers. They might have special jutsu combinations that no one has seen before, like a mix of water and lightning jutsu to create a powerful electric - charged water attack.
His soldier - like behavior could initially cause some distance. His friends might be a bit intimidated because soldiers are often associated with strict discipline. However, as they get used to it, they would realize that Naruto is still the same person deep down. He just has a new sense of duty that can actually help protect them all in the long run.
The US soldier could be a reincarnation of a powerful ninja in the Naruto universe. They start to have strange dreams about the Naruto world and gradually discover their past life. With their modern - day military knowledge and the latent ninja powers from their reincarnated self, they can make a big impact. For instance, they might introduce new forms of weaponry or training methods to the ninja, which could be a fresh take in the fanfic.
It's possible that there are other original characters created for the fanfiction as well. For example, there could be a mentor figure for the soldier of fortune, someone who has been in the business of being a soldier for a long time and imparts their wisdom and skills to the main character. Or there could be a rival soldier of fortune who is constantly trying to outdo the main character in various missions and challenges.
Another theme is the struggle for identity. When Naruto is a child soldier, he may question his purpose and who he really is. Is he just a weapon for the village, or is there more to him? This internal conflict can be a major part of these fanfictions.