In this kind of fanfiction, Mizuki might save Naruto from a dangerous enemy attack. Maybe he uses his own skills to fight off the attackers who are about to harm Naruto.
Kakashi could also be a common character. He is Iruka's colleague and they both play important roles in Naruto's life. In time travel scenarios, Kakashi might be involved in helping Iruka adjust to the time - shifted situation or they could work together on a mission that is affected by Iruka's time travel.
It's possible that Mizuki has had a change of heart. He might have seen the error of his ways in the original story and now wants to make amends by saving Naruto. He could have reflected on how his actions in the past were wrong and this is his way of redeeming himself. In this fanfiction, he might be trying to create a new, positive relationship with Naruto based on mutual respect and friendship.
Well, in the fanfiction, Iruka may be protective by constantly checking on Naruto's well - being. He could ensure Naruto has enough to eat, is getting proper training, and is not being bullied by other villagers. He might also be protective in the sense that he gives Naruto extra attention and guidance in his ninja training, more so than he would for other students.
I really liked 'Mizuki's Redemption Arc'. In this fanfic, Mizuki realizes the error of his ways after his initial betrayal. The author does a wonderful job of writing Naruto's reaction to Mizuki's attempts at redemption. It's a heartwarming story that shows the power of forgiveness in the Naruto universe.
One scenario could be when some villagers start to be mean to Naruto. Iruka steps in and scolds them, telling them Naruto is just a kid. Another could be during a training exercise that gets a bit too dangerous for Naruto, and Iruka quickly intervenes.
It also improves Naruto's skills a great deal. He becomes better at combat and using his ninja techniques. For example, his Rasengan might be more powerful or more easily controllable after Iruka's training. Moreover, Naruto's confidence grows under Iruka's guidance. He no longer doubts himself as much and is more willing to take on challenges.
Physically, Iruka takes care of Naruto's symptoms. If Naruto has a cough, Iruka might make him herbal tea to soothe his throat. If Naruto has a fever, he uses cold compresses to bring the temperature down. He monitors Naruto's condition closely and adjusts his care accordingly, making sure Naruto is on the road to recovery as quickly as possible.