Well, if Naruto and Sakura were twins in a fanfiction, their relationship with Sasuke would be quite different. Naruto might be more protective of Sakura as his twin sister. He would be more likely to step in between Sasuke and Sakura if Sasuke ever made Sakura sad or angry. Sakura, on the other hand, would have the support of her twin Naruto. She might be more confident in dealing with Sasuke, knowing she has Naruto by her side. Maybe she would be less desperate for Sasuke's attention as she has a stronger family bond with Naruto.
Well, they'd probably have a stronger initial bond. Instead of starting off as rivals, they might be more like partners from the start. They'd have a natural inclination to look out for each other more directly.
In the hospital setting, Sasuke might initially be his aloof self. But as Sakura takes care of him or they face challenges together, he could start to open up more. For example, if Sakura is overworked, Sasuke might offer a helping hand in small ways, like getting her coffee. This would show his growing affection for her.
Their relationship would likely become more intense. As vampires, their emotions might be heightened. They could become more possessive of each other. For example, Sasuke might be more protective of Sakura, seeing her as his mate in the vampire sense.
The dynamic would be turned upside down. Sasuke would likely become more of an outcast or a loner, feeling rejected. Naruto would be in a difficult position, having to balance his friendship with Sasuke and his new relationship with Sakura. Sakura would be the catalyst for this change, and she would have to face the consequences of her actions, like dealing with the villagers' opinions and the potential backlash from Sasuke's supporters.
The twins would likely have a very loving relationship with Naruto. Naruto, having grown up without parents himself, would be extremely affectionate and dedicated to his children. He would teach them important ninja values and skills, and also share his own experiences with them.
During their travels, they would have to depend on each other. Sasuke might protect Sakura from physical threats, and Sakura would take care of Sasuke when he's injured. This mutual reliance would bring them closer. They'd also have time to talk about their dreams and fears, which would further develop their relationship into a more loving and trusting one.
At the beginning, their relationship might be a bit rocky. Sasuke is used to being alone, and Sakura has to adjust to his way of doing things. However, as they face challenges together, like fighting off enemy ninjas or surviving in harsh environments, they start to bond. Sakura's constant support and her growth as a ninja start to make Sasuke respect her more. Eventually, this respect could lead to a more intimate relationship where they truly open up to each other.
Their relationship could become more strained. Sakura might be afraid of Sasuke after the bite, creating distance between them. Sasuke, on the other hand, could be filled with regret and try to avoid her, which would further complicate their relationship.
Their relationship would likely become more intimate and committed. With a baby on the way, Sasuke would feel a greater sense of responsibility towards Sakura. He might be more protective and stay closer to her.
It would likely become more cooperative. They'd have to communicate more often to take care of the pregnancy - related matters.