One possible antagonist could be Orochimaru. He has always been interested in Naruto for his Nine - Tails power, so it would make sense for him to be a threat that Kakashi has to protect Naruto from.
When Naruto saves Kakashi, it often shows his growth in terms of leadership. He has to take charge of the situation, which is different from his earlier, more impulsive self. For example, if he has to organize a rescue mission, he learns to plan and delegate tasks to others.
Well, it could be that in the fanfic, Kakashi saves Naruto from a trap set by Orochimaru. Kakashi arrives just in time, using his lightning - style jutsu to break through Orochimaru's defenses and snatch Naruto away from the clutches of danger. This would create a tense and exciting moment in the story.
One possible antagonist could be the Akatsuki members. They are always looking for strong opponents or valuable information. Maybe they target Iruka because they think he has some knowledge about Naruto that they can use, and Kakashi has to stop them.
In such a fanfiction, perhaps Kakashi might save Iruka from a dangerous enemy like Orochimaru's minions. Kakashi, with his Sharingan and powerful jutsu, could arrive just in time to fend off the attackers.
In some fanfictions, Naruto saves Kakashi from the brink of death. For instance, Kakashi could be poisoned by a rare and deadly toxin. Naruto, with his determination, goes on a quest to find the antidote. He overcomes many obstacles, battles different creatures, and finally retrieves the antidote to save Kakashi. This showcases Naruto's loyalty and his growth as a shinobi.
The moment when Kakashi actually reaches Naruto and stops him from harming himself is crucial. He could use his speed and strength to grab Naruto's hands if he was about to use a weapon on himself. Kakashi's presence alone at that moment can be a shock to Naruto, making him pause and re - consider.
It might also make Kakashi more protective of Naruto in the future. He realizes how important Naruto is not just to the village but also to him personally. So, he may be more involved in Naruto's training and growth.
The key events could start with the villagers gathering around Naruto with malicious intent. Kakashi, being perceptive, senses the danger and hurries to the location. Once there, he uses his reputation as a powerful ninja to try and diffuse the situation. But the villagers, blinded by their prejudice, don't back down easily. So, Kakashi has to take physical action. He might use his ninja tools to create a barrier between Naruto and the villagers. As they try to break through, he then takes Naruto and jumps onto the rooftops, starting a chase sequence. During this chase, Kakashi has to constantly protect Naruto from attacks while also finding a way to lose the pursuers. Eventually, they reach a safe haven, which could be a place only Kakashi knows about, and this marks the end of the immediate danger for Naruto.
The appeal lies in the dynamic between Kakashi and Sakura. Kakashi is a highly skilled and respected ninja, and seeing him come to Sakura's rescue plays into the idea of the strong protecting the vulnerable. It also shows their relationship, which can be explored in different ways in fanfiction.