It could be an orphan who has been living on the streets of the Hidden Leaf village. This child might have some hidden potential, like being a descendant of a powerful ninja clan but unaware of their heritage.
The theme of survival is often present. Being lost in the Naruto world can be dangerous, so characters have to find ways to survive. They might have to deal with hostile ninja clans or dangerous beasts. Another common theme is the search for a way back. Whether it's back to their own time, place, or to their friends, the character is constantly striving to return to what they consider 'home' in the Naruto universe.
It could be about Naruto finding and reclaiming a lost child within the Naruto universe. Maybe it's a story where Naruto stumbles upon a child who has lost their way, either literally in the Hidden Leaf village or metaphorically in terms of their ninja path, and Naruto takes it upon himself to help the child find their place again.
One great 'Naruto Lost Tower' fanfiction is 'Time's Echo in the Lost Tower'. It delves deep into Naruto's emotions as he navigates the mysteries of the Lost Tower. The author does an amazing job of exploring Naruto's character growth during this adventure, and the plot twists keep you on the edge of your seat.
A 'lost naruto fanfiction' might involve Naruto being lost in an alternate reality where the Akatsuki are the good guys. He is completely confused at first, but as he spends time there, he starts to understand their motives. He has to decide whether to try and change this reality back to what he knows or accept the new order. It could be a story full of moral dilemmas and exciting battles.
The Hokage, like Kakashi or Tsunade, could also be important characters in this fanfiction. They would have to deal with the political implications of Naruto being a lost prince. Their reactions could range from trying to protect Naruto and use his new status for the good of the village, to being worried about how it will disrupt the existing power structure.
One common theme is loneliness. Naruto already felt lonely in the original story, but losing his family in fanfiction magnifies this. Another theme is revenge. He might be more driven to seek revenge against those who he believes are responsible for his family's death. Also, self - discovery is a big theme. Without his family, he has to figure out who he really is on his own.
It could be about various things. Maybe it focuses on an alternate story within the Naruto Shippuden: The Lost Tower setting. It might explore different relationships between characters that were not fully developed in the original movie. For example, it could expand on the backstory of some minor characters or create new adventures for Naruto and his friends in that particular time and place.
It could be about a character getting lost in some sort of green, perhaps forest - like or oceanic - like areas in the Naruto universe. Maybe it's a story of self - discovery as the character battles the unknown elements of these green seas.
Naruto might develop a deeper understanding of sacrifice. His lost arm is a physical reminder of the risks he takes in battle. This could lead to him being more cautious while still maintaining his fearless attitude when it comes to protecting what he loves. He also may become more empathetic towards others who have physical disabilities or losses.