Well, Naruto would likely be one of them. He has a big heart and would surely want to help his fellow villagers. Sakura could also be involved as she is a skilled medical ninja. She could use her medical knowledge to diagnose and treat their illness.
One possible plot could be that while they are sick, their comrades in Konoha come together to take care of them. Maybe Naruto brings them some of his favorite ramen, thinking it might cheer them up and help them get better.
A common theme is friendship. Kotetsu and Izumo are often depicted as having a strong bond in fanfics. Another theme is their loyalty to Konoha. Their role as guards and their commitment to the village are frequently explored.
Well, it could be about Kotetsu and Izumo facing a really tough mission that turns into a nightmare. Maybe they get trapped in a genjutsu created by a powerful enemy. In this genjutsu, they relive their worst memories, like failing important missions in the past. And they have to find a way to break free together, relying on their friendship and the skills they've developed over time.
Another jutsu Naruto could learn is a defensive one. Given that Kotetsu and Izumo have to protect themselves and others, they might teach Naruto a jutsu that creates a stronger shield or barrier. This would enhance Naruto's survivability in battles, especially against powerful opponents. It could be a jutsu that combines chakra control and some form of elemental manipulation, which Naruto can then adapt to his own style with his large chakra reserves.
One popular 'naruto kotetsu and izumo fanfic' is 'Kotetsu and Izumo's Unseen Missions'. It delves into their daily tasks in Konoha that are often overlooked in the main series. Another great one could be 'The Bond of Kotetsu and Izumo' which focuses on their friendship and how it has developed over the years.
It could be a rogue ninja who has a vendetta against Konoha. This ninja might target Kotetsu and Izumo specifically because they are guards of the village gates. They see them as easy targets to start their revenge plan against Konoha.
Well, Naruto might incorporate more teamwork - based tactics into his combat style. Since Kotetsu and Izumo are used to working together, they could instill in Naruto the importance of coordinating with his allies. He could start using moves that complement his teammates' abilities more often, and be more aware of his position in a group fight.
Another interesting one is 'Kotetsu's Training Days'. This fanfiction delves deep into Kotetsu's training regime. It shows how he overcomes difficulties, learns new jutsu, and forges strong bonds with his training partners. It gives a great insight into his character development.
One common theme is loyalty. Kotetsu is often depicted as being extremely loyal to the Hidden Leaf Village, and fanfictions explore this loyalty further, like in situations where he has to choose between the village and his personal beliefs.