Well, perhaps a plot twist could be that an old enemy resurfaces but this time they target Hinata to get to Naruto. This forces Naruto to not only protect his new wife but also figure out why this enemy is after her specifically. It could also add a layer of drama if Hinata decides to take matters into her own hands and train secretly to be able to defend herself and Naruto better. Or, there could be a political plot twist where their marriage causes unrest in the ninja world because of Hinata's family status and Naruto's position as a hero, leading to them having to fight against those who oppose their union.
One interesting plot twist could be that Naruto initially thought he was only in love with Hinata, but during a dangerous mission where Hanabi's life was on the line, he realized he had deeper feelings for her as well. Another could be that there is a prophecy that foretells of a union between the Uzumaki, Hinata, and Hanabi which would bring great power and peace to the ninja world, forcing the characters to consider this unconventional relationship.
A plot twist could be that Sakura and Hinata actually team up against Naruto in some way. Perhaps they realize that Naruto is being pushed into a relationship by the village elders for political reasons. So, they decide to fake a relationship between themselves to make Naruto see that he should be free to choose his own path and not be pressured into a marriage. This would turn the typical love triangle on its head.
One possible plot twist could be that during their training, they accidentally discover a new and powerful jutsu. Maybe it's a jutsu that combines their unique abilities. Naruto's chakra control could be enhanced by Hinata's gentle fist style in an unexpected way, leading to a whole new form of attack or defense.
Well, a plot twist might be that when Naruto arrives to save Hinata, he finds out that Hinata has already made a deal with the Kumo ninjas for the sake of Konoha. So Naruto has to figure out how to honor Hinata's decision while still protecting her. Also, it could be that the Kumo situation is just a cover - up for a much larger conspiracy involving other villages. And there's a chance that the person Naruto thought was Hinata in danger was actually a clone, and the real Hinata is in an even more dangerous situation elsewhere.
A plot twist could also be that Temari discovers a long - lost relative who has a dark past and tries to use Naruto's influence for evil purposes. Temari would be torn between family loyalty and her love for Naruto, and Naruto would have to help her make the right decision while also protecting their relationship and the villages.
A possible plot twist could be that the demon Naruto marries is actually a reincarnation of an ancient and powerful being, which brings a whole new level of danger and mystery to the story.
Another plot twist could be that Naruto's own chakra has an unexpected effect on the vampire. Perhaps it changes the vampire in some way, either making them more powerful or causing some sort of internal struggle within them. This would then have a big impact on their relationship as they both have to figure out how to deal with this new situation.
Their married life would be full of love and support. Naruto, being the energetic and passionate person he is, would always bring excitement to their home. Hinata, on the other hand, would be the calm and nurturing presence. They would train together, and Naruto would learn more about Hinata's gentle side, while Hinata would see Naruto's determination up close. They'd also have to deal with normal couple things like cooking together (though Naruto might burn a few things at first), and just enjoying each other's company at home.
One of my favorite plot twists in Naruto Road to Ninja Hinata fanfiction is when Hinata gets a power - up that no one expected. It completely changes the dynamic of her character and how she interacts with others. Suddenly, she's not just the shy Hinata we know, but a force to be reckoned with.
One possible plot twist could be that Naruto and Hinata have to quickly learn to control their newfound Jinchuuriki powers. Maybe they are suddenly thrust into a situation where an ancient evil is awakened and only their combined Jinchuuriki abilities can stop it. For example, they might discover that there is a hidden prophecy about two Jinchuuriki working together to save the world.