The theme of hope against all odds is also present. Despite his sad childhood, Naruto in fanfiction always has that glimmer of hope that things will get better. He believes in himself and his future, even when no one else does, and this is something that fanfic authors like to emphasize.
Loss is often seen. It could be the loss of a loved one, like a parent or a sibling. This creates a void in the child's life that is hard to fill. Also, bullying at school is a theme. Being constantly picked on by peers can make a child's childhood very sad.
Unfulfilled dreams can also be a theme. Naruto has always dreamed of becoming Hokage to gain the respect and recognition of the village. If in a fanfiction, something prevents him from achieving this dream, like an unexpected injury or a political conspiracy, he would be extremely sad. He has put so much effort and hope into this dream, and to see it slip away would be a huge blow to him.
Friendship is a common theme. In many fanfictions, it shows how Naruto and Sasuke's bond began as kids. It was a unique friendship, full of both competition and mutual understanding.
Common themes in such fanfictions include the exploration of Naruto's pain. His horrible childhood was filled with pain from being orphaned and not having a family. This pain can be a central theme, showing how it affects his actions and relationships. Another theme is the idea of resilience. Naruto had to be strong in the face of a difficult childhood, and fanfictions may expand on how he builds that resilience. And there's often the theme of hope. Despite all the bad things in his childhood, Naruto always had a glimmer of hope, and this can be a significant part of these fanfictions, showing how that hope sustains him through his struggles.
One common theme is loss. It could be the loss of a loved one, like a grandparent or a pet. Another theme is loneliness, such as when a child is bullied and has no friends to turn to. Also, disappointment can be a theme, like when a child has a big dream but their family can't support it due to financial reasons.
Unrequited love is a common theme. Often, characters in the harem have feelings for Naruto that are not reciprocated, leading to sadness. Another theme is sacrifice. Some characters might sacrifice their own happiness for the sake of the group or Naruto, which is really sad.
Betrayal can also be a big theme. Maybe in fanfiction, Naruto is betrayed by someone he thought was a close friend, adding to his already heavy burden of sadness. This could be a new character or an existing one taking a different path in the story.
One common theme is isolation. Since Naruto had a bad childhood, fanfictions often focus on how he was alone as a child. Another theme is the search for identity. He didn't have his parents, so he's constantly trying to figure out who he is in these stories. And revenge can also be a theme. Some fanfictions might explore if Naruto would seek revenge against those who made his childhood miserable.
One common theme is the power of friendship. Their bond helps them both grow and overcome their respective traumas. For example, Naruto's friendship gives Gaara a reason to believe in himself more.
One common theme is loss. This could be the loss of a loved one like a grandparent or a pet. For example, when a grandparent who used to spoil the child with love and stories passes away, it leaves a big void in the child's heart. Another theme is loneliness. Maybe the child moved to a new place and had trouble making friends. They would spend a lot of time alone and feel really sad about it.