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.
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.
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 common theme is the clash of ideals. Sakura, who represents the new generation of Konoha ninjas with their more positive and community - oriented values, often clashes with Zabuza, who was a ruthless assassin. This contrast creates interesting dynamics in the stories.
In most traditional 'Naruto' lore, Naruto has no relation to Zabuza. However, in fanfiction, the author can create any alternate reality they like. So, it's possible for Naruto to be Zabuza's son in some fan - made stories. But this goes against the original story's character backgrounds and relationships.
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.
One popular sakura and zabuza fanfiction is 'The Unlikely Bond'. In this story, Sakura, instead of being just a medic - ninja, finds herself in a situation where she has to team up with Zabuza. Their interactions start off rocky but gradually they come to understand and respect each other. It's a really interesting take on their characters.
You can start by looking on fanfiction.net. It has a large collection of Naruto - related fanfictions, including those with Zabuza crossovers. Another good place is Archive of Our Own (AO3). It has a wide range of fan - created works, and you're likely to find some interesting Zabuza crossover fanfictions there.