A Naruto fanfiction can be sad when it delves into the sacrifices Naruto has to make. He gives up so much of his personal life and relationships for the sake of the village and his friends. If a story highlights how he loses his close friends, like Sasuke in some darker interpretations, it can be extremely sad. Additionally, if it shows Naruto being misunderstood by the people he's trying to protect, that also adds a layer of sadness. For instance, if the villagers still don't trust him despite all his efforts, it can be a very tragic situation for Naruto.
Well, Kurama's sad story in Naruto Shippuden is complex. He was feared by the villagers in the Hidden Leaf because of his power. When he was sealed into Naruto, he was angry and tried to take over Naruto's body multiple times. His past was filled with being hunted and then trapped. It wasn't until he started to understand Naruto's will and dreams that he began to change. Naruto's unwavering determination and kindness towards him slowly melted his cold heart.
One sad story in Naruto is about Sasuke. His entire clan was massacred when he was young. He had to live with this trauma and the thirst for revenge. He left his friends in Konoha, like Naruto who considered him a brother, to seek power from Orochimaru. This led to a long separation and many battles between them.
Loss is a very common theme. This could be the loss of a friend, like Sasuke leaving Naruto. It creates a deep sense of sadness as Naruto has to deal with the emptiness.
'Abandoned Hope' is also great. It focuses on Naruto's feelings of abandonment as a child. The fanfic paints a very sad picture of his early days, with him constantly longing for acceptance and love. It's a heart - wrenching read as it shows how Naruto's positive attitude is a mask for his deep - seated pain.
One aspect of Naruto's sad childhood in fanfiction could be his loneliness. He was shunned by the villagers because of the Nine - Tails inside him. In many fanfictions, authors explore how he coped with this isolation, like finding solace in small acts of kindness from a few people, such as Iruka - sensei.
The death of Neji is also a very sad story in Naruto. Neji was a strong and important character. His sacrifice during the Fourth Great Ninja War was unexpected and heart - wrenching. Naruto was deeply affected by it as Neji was his comrade. It was a tragic moment that added to the overall sadness in the story.
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.
Communication is key. If Naruto finally realizes Hinata's love and they sit down and talk about their feelings, it could start to mend things. Naruto could share his own insecurities that made him blind to her love before.
One possible plot could be Naruto spending his birthday alone in his apartment. All his friends are out on a mission or too busy with their own lives. He looks at old pictures and回忆起 his lonely childhood birthdays, which makes him sad. He starts to question his place among his friends and whether he really matters to them.