It's popular because the relationship between Kakashi and Naruto is a central and beloved part of the Naruto series. Fans love to see more of their dynamic, especially when Kakashi is in a protective role over Naruto.
One example could be a fanfiction where Naruto is wrongly accused of something in the village, and Kakashi steps in to defend him using his wisdom and influence. Another might be a situation where Naruto is facing an external threat and Kakashi defends him on the battlefield, which is then detailed in the fanfiction.
Well, Naruto has a lot of ways to defend himself in fanfiction. One of the main things is his ability to sense danger. This comes from his training as a ninja. He can then quickly counter - attack using his ninjutsu skills. For example, he can create multiple shadow clones to confuse his enemies and then attack from unexpected angles. His connection with the Nine - Tails also gives him extra strength when needed, which is a great asset in defending himself.
Physically, Naruto can use his Rasengan or other powerful jutsus to fend off enemies attacking Boruto. His combat skills are top - notch, and he won't hesitate to engage in battle to keep Boruto safe.
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.
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.
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.
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.
A frequent situation where Naruto defends himself in fanfiction is when he is targeted because of his status as a Jinchuriki. Enemies may try to capture or kill him to gain control of the Nine - Tails' power. Naruto has to use all his skills, from his ninjutsu to his strategic thinking, to defend against these threats. He also defends himself when he is involved in disputes within his own village, either because of political reasons or misunderstandings among the ninja clans.
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.