One possible plot could be that Naruto meets Zabuza's apprentice during a mission. The apprentice, having grown up with Zabuza's teachings, initially has a rather cold and ruthless attitude. Naruto, with his usual optimistic and friendly nature, tries to befriend the apprentice. This could lead to the apprentice slowly changing their views on life and friendship, and perhaps they end up joining Naruto on his journey to protect the village.
One possible plot could be Naruto learning Zabuza's unique water jutsu techniques. For example, he might master the Hidden Mist Jutsu which Zabuza was famous for. This would give Naruto an edge in combat, especially in stealthy attacks.
One possible plot could be that Naruto uses his shadow clones in a really unexpected and spooky way to scare Zabuza. For example, he could make the clones appear out of thin air in a dark and misty forest where Zabuza is. The clones could make strange noises and movements that Zabuza has never seen before, making him feel uneasy. Since Zabuza is used to being the one who instills fear in others, Naruto's sudden scare tactics would throw him off balance.
A really interesting plot twist could be that Zabuza has a hidden past or connection to Naruto's family. For instance, perhaps he knew Naruto's father in a different context than what was previously known. This could change Naruto's whole perspective on his family and his place in the ninja world. Or, Zabuza could have been given a secret mission long ago related to Naruto that he never fully completed, and now raising Naruto becomes a way to fulfill that mission. This would add a whole new layer of mystery and depth to the fanfic.
Another plot could be that Zabuza's sword ends up in the hands of an enemy of Konoha. Konoha sends a team of ninjas, including some of the younger generation like Naruto and his friends, to retrieve it. Along the way, they learn about Zabuza's legacy and the true strength of the sword. They have to battle the enemy who has already started to unlock some of the sword's powers, but in the end, they manage to get it back and decide what to do with such a dangerous weapon.
At first, the apprentice might see Naruto as an enemy or at least a nuisance. However, Naruto's determination and his ability to never give up could intrigue the apprentice. As they are forced to work together on various tasks, they would start to understand each other better. Naruto could learn about the apprentice's loyalty to Zabuza and the apprentice could learn about Naruto's loyalty to his friends and village. This mutual understanding would lead to a deeper relationship.
One possible plot twist could be that Zabuza's training methods lead Naruto to develop a darker side. Naruto might start to question his own values as Zabuza's more ruthless ways of fighting seep into his mindset. For example, he could become more willing to use underhanded tactics in battles, which would shock his friends.
One possible plot could be that Naruto, under Zabuza's training, learns new and unique water - style jutsu. Zabuza, being a master of silent killing, could teach Naruto stealth techniques. Naruto might also gain a different perspective on the shinobi world from Zabuza, who has a more ruthless view compared to his usual teachers. This could lead to internal conflicts within Naruto as he tries to balance his own values with the new knowledge.
The plot could involve the apprentice learning Ibiki's interrogation techniques. Maybe they start with basic training like how to read body language during an interrogation. For example, learning to notice when a suspect is lying by small twitches or changes in eye movement.
One possible plot could be that Naruto, through some strange twist of fate or magic, forms an unexpected bond with Zabuza. Maybe they start off as enemies as in the original story but then gradually come to understand each other. Naruto's positive and determined attitude might start to influence Zabuza, and they could end up teaming up against common foes in the ninja world.
One possible plot could be that Naruto's kid discovers their own unique ninja abilities. Maybe they struggle at first to live up to Naruto's legacy but then find their own path. For example, they might be more interested in healing jutsu rather than combat like Naruto was.