Sasuke could be a popular character. He might be involved in the story in a way that either helps or hinders the situation where Naruto hurts Kakashi. For example, if Sasuke tries to stop Naruto from doing something stupid that would hurt Kakashi.
One common theme could be Naruto making a mistake that physically or emotionally hurts Kakashi. For example, he might accidentally use a new jutsu that backfires and injures Kakashi. Another theme could be Naruto's actions causing Kakashi to feel betrayed, like if Naruto were to side with an enemy temporarily.
Well, there could be. Fanfiction writers love to explore unique and unexpected relationships. Since Naruto and Kakashi are both popular characters in the Naruto universe, some writers might come up with such a plot for the sake of creativity and exploring different storylines. But it's not a part of the official Naruto story.
Another reason could be related to Kakashi's past actions. If there are some secrets or things Kakashi did in the past that come to light and Naruto doesn't like them, he could snap at Kakashi. Naruto has a strong sense of justice and loyalty, so if he feels betrayed or misled by Kakashi, his reaction could be to snap.
They are popular because the relationship between Obito and Kakashi is complex. Their history as friends turned enemies creates a lot of drama. Fans are interested in exploring how Obito's actions impact Kakashi.
One good 'Obito Hurts Kakashi' fanfiction could be 'The Pain of Betrayal'. In it, Obito's actions deeply wound Kakashi both physically and emotionally. Another might be 'Fractured Bonds' where Obito's choices lead to Kakashi's internal turmoil. There's also 'Shadows of the Past' which explores how Obito's actions haunt Kakashi over time.
Kakashi might be initially surprised. But then, he would probably use it as a teaching moment for Naruto. He could say something like 'Naruto, stealing is not the way of a ninja.' And then give him a punishment like extra training.
The story could develop with other characters getting involved. For example, Sasuke might hear about what happened and come back to the village to confront Tsunade. This would create a lot of tension and drama in the fanfiction.
One possible reason could be that Kakashi is preoccupied with other important matters in the village. Maybe he has some top - secret missions or tasks assigned by the Hokage that demand his full attention, leaving him with little time to focus on Naruto.
One reason could be that he sees Naruto as a younger version of himself in some ways. Both have had their share of loneliness and challenges growing up. Kakashi may want to prevent Naruto from going through the same pain he did. Another reason is Naruto's importance to the village. As the jinchuriki of the Nine - Tails, Naruto is a key asset. Kakashi, being a loyal ninja, wants to protect the village's future which is tied to Naruto.