One interesting plot idea could be Kakashi getting transported into a different Naruto timeline where all the villains have joined forces. He'd have to use his Sharingan and vast combat experience to survive and find a way to stop them. Another could be Naruto and Kakashi swapping bodies for a while. This would lead to some comical situations as Naruto tries to act like Kakashi and vice versa. Also, a crossover where Kakashi is sent to a parallel universe where Naruto doesn't exist, and he has to train a new group of ninja in the ways of Konoha.
One plot could be a crossover where Kakashi is given a new mission by the Hokage. He has to go to a far - off land to retrieve a powerful artifact. Naruto, being his eager self, convinces Kakashi to let him come along. Along the way, they meet new and strange ninja tribes. These tribes have unique jutsu that Kakashi and Naruto have to learn in order to defeat the guardians of the artifact. Another interesting plot is that a time - traveling device sends Kakashi back to when Naruto was a child. Kakashi has to make sure that Naruto's early life doesn't get derailed by any unseen threats while also trying not to change the future too much.
A great plot for Naruto Kakashi crossover fanfiction could be Kakashi going on a mission in a hidden land that is filled with dark magic. Naruto secretly follows him, and they end up having to face a powerful dark wizard together. Since Naruto doesn't know much about this type of magic, Kakashi has to teach him quickly while also fighting off the wizard's minions. Another idea is that Kakashi and Naruto are both sucked into a genjutsu world created by an ancient enemy. In this world, they have to relive their worst nightmares and break free to defeat the enemy who trapped them there.
A possible plot is that Naruto discovers a hidden power within Kakashi that even Kakashi was unaware of. This discovery leads them on a journey to explore the origin of this power. Maybe it's related to an ancient clan. As they dig deeper, their relationship grows stronger and they face many challenges together from enemies who also want this power.
One idea could be a story where young Kakashi has to protect a young Naruto from a group of rogue ninjas. It could show Kakashi's early skills and Naruto's innocent yet determined nature.
A really interesting plot for 'kakashi and naruto family fanfiction' could be that Kakashi accidentally stumbles upon a secret power within Naruto's family that has been dormant for generations. He then helps them unlock and control this power. Along the way, they form a stronger bond as a family. And as Kakashi is involved, he also rediscovers some of his own values and beliefs through this process.
One plot idea could be that the female Naruto has a special training session with Kakashi. During this, she discovers a new jutsu that Kakashi has been secretly working on. He decides to teach it to her because he sees her potential. This new jutsu then becomes crucial in a future battle against a powerful enemy.
One idea could be that little Naruto gets lost in the forest and Kakashi has to find him. Along the way, Kakashi discovers Naruto's secret hiding place filled with his dreams and wishes written on little scrolls.
One idea is that an enemy targets Kakashi's Sharingan and Naruto has to protect it. Along the way, Naruto learns more about the Sharingan's capabilities and how to use it against the enemy. This would be a great opportunity for Naruto to grow as a ninja and for their friendship to deepen.
One idea could be that Female Kakashi is assigned to train Naruto in a special jutsu. During their training, they discover a long - forgotten scroll that contains a powerful technique. As they work together to master it, they face challenges from other ninja who want the scroll for themselves.
One idea could be a crossover with the Harry Potter universe. Kakashi could be a visiting wizard from another dimension, teaching the students at Hogwarts some of his ninja skills. Another could be a crossover with the Avengers. Kakashi's stealth and combat skills would make him a great addition to the team, and it would be interesting to see how he interacts with the likes of Iron Man and Captain America. A third idea might be a crossover with the Lord of the Rings. Kakashi could be a ranger in Middle - earth, using his Sharingan to detect the presence of orcs and other dark forces.
Another plot could involve Naruto training a group of new genin in the same strict yet effective way that Kakashi trained him and his friends. Along the way, he discovers that one of the genin has a hidden power similar to his own, and they bond over their shared experiences of being different. This story could show Naruto's growth as a teacher and as a ninja who is now emulating Kakashi.
One interesting plot idea could be Kakashi traveling back in time to before the Uchiha massacre. He could try to prevent it, which would completely change the future of the Naruto world. Maybe he'd have to face off against Danzo and his schemes early on.