Haku should definitely be included. Since Haku was Zabuza's loyal follower, his presence can add depth to the story. He could act as a mediator between Naruto and Zabuza at times. Also, Kakashi can be a great addition. His history with Zabuza makes for an interesting dynamic, and his mentoring of Naruto can play a role in how Naruto interacts with Zabuza.
Zabuza could be quite cold to Naruto at the beginning. He's not exactly the warm - and - fuzzy type. But when Naruto shows his skills and tells his story of being banished unjustly, Zabuza might empathize on some level. He might not show it openly, but he could start to protect Naruto in his own way, perhaps because he sees a bit of his younger self in Naruto who was also wronged by the ninja system.
He could learn Zabuza's signature water - style jutsu, like the Hidden Mist Technique. This would give Naruto an advantage in terms of creating diversions and hiding his movements during battles.
Zabuza could be portrayed as more of a mentor figure. Instead of just being a ruthless assassin, he could be shown guiding Naruto in some aspects of combat or strategy. Maybe he survived his encounter with Kakashi and had a change of heart, and now he imparts his knowledge to Naruto who is now a sensei himself.
On a more practical level, Naruto's skills might be misused. Instead of using his power to protect Konoha and the people he cares about, he's using it for Zabuza's self - centered motives. This could also make him a target for other ninja who oppose Zabuza. So not only is he in danger from the people he used to call friends, but also from new enemies. And if he ever tries to break free from Zabuza, he might face severe retaliation from Zabuza himself, which could be life - threatening.
Sasuke would probably be very suspicious at first. He doesn't trust easily and seeing Naruto with Zabuza, an enemy in his eyes, would make him question Naruto's motives. Kakashi, on the other hand, might be more open - minded. He would likely keep an eye on the situation to make sure Naruto isn't being led astray but also recognize that Naruto has a way of changing people for the better.
Well, Naruto is a very impressionable character. His idolization of Zabuza might make him more open to using unorthodox or morally grey techniques. He could start to question the black - and - white view of good and evil that he initially had. Maybe he would see the value in Zabuza's loyalty to Haku, which could in turn strengthen Naruto's own bonds with his friends.
Well, it could be due to some sort of mind - control jutsu. Maybe Zabuza uses a special technique that he learned in the Hidden Mist Village to make Naruto do his bidding.
One possible consequence could be that Naruto gains a new and powerful weapon. This sword might have unique abilities that could enhance his combat skills. He could use it to intimidate his enemies or as a last - resort weapon when his regular jutsu are ineffective.