She becomes more cautious. She has to watch every move she makes to avoid revealing her true nature.
When Vampire Bella goes to school in Twilight fanfiction, her behavior is quite different. She is more withdrawn. She used to be more involved in school life as a human, but now she keeps to herself. She is also very careful about her reactions. For instance, if there's an accident at school and someone gets hurt, she has to suppress her natural vampire instincts to be drawn to the blood. She might also seem a bit aloof, but it's really just her way of protecting herself and others from her vampire self.
In Twilight fanfiction, Vampire Bella going to school has multiple difficulties. Firstly, her appearance. Even though she tries to blend in, her pale skin and other vampiric features might make her stand out. Secondly, her academic performance. With her new vampire - enhanced mind, she may find it hard to not seem too smart and draw unwanted attention. Thirdly, the relationships. She has to keep her distance from her old human friends in a way that doesn't seem too odd, while also dealing with any new vampire - related relationships that might form at school.
Her relationship with Bella would likely become more complex. As a vampire, she would have different needs and instincts. She might be more protective of Bella in a way that Bella doesn't understand at first. For example, she could sense danger towards Bella that a human wouldn't notice. But at the same time, Bella might be a bit afraid of her sister's new vampire nature, which could create some tension between them.
She might develop a stronger sense of identity. In the original 'Twilight', her identity was often tied to the men in her life. But as the princess of the Volte, she has her own power base and a group that looks up to her. This gives her a new sense of self - worth and purpose that shapes her character in a different way.
The plot changes drastically. For starters, the Cullens might have to deal with the fact that Bella is now bitten by a rogue vampire. They may face some internal conflict about whether to help her or not. Edward's character would be deeply affected as his love for Bella is put to the ultimate test. He has to decide if he can still be with her now that she's been bitten by his enemy.
When Bella is drunk in Twilight fanfiction, her character can become a bit more unpredictable. Her emotions may be heightened, so she could go from being happy and giggly one moment to being sad and crying the next. This change in her emotional state can put a strain on her relationships. For instance, Edward might be confused by her sudden mood swings and not know how to handle her in this new state. Also, her friends like Jessica and Angela might be shocked to see this different side of her and react in various ways, which in turn affects the overall dynamic of the story.
Well, in this fanfiction, Bella might face challenges in hiding her vampire nature at school. For example, she could struggle with controlling her super strength during gym class or her enhanced senses in a crowded cafeteria. Maybe she'll have to deal with other students who are suspicious of her new, more alluring appearance.
His daily routine would be completely different. Instead of going to classes like Potions and Transfiguration, he'd be in Math and History classes. He might feel bored at times because he's used to the more exciting and magical learning at Hogwarts.
In fanfiction, the imprint can lead to a deeper emotional connection. Jacob may understand Bella's feelings and needs on a more profound level. He might be able to sense when she's in distress, even from a distance. This new - found closeness can also make Bella more open to Jacob, and she may start to see him in a different light, not just as a friend but as someone with a special bond to her.
If Bella were a vampire from the beginning, her relationship with Edward would be different. They would be equals in terms of strength and immortality. There might not be the same level of protectiveness from Edward as he wouldn't need to worry about her being so fragile. Their relationship could be more of a partnership in the vampire world.
It also makes her more patient. Vampire children, or even adult vampires she might be mothering in the fanfiction, can be difficult to understand and manage. Bella has to learn to be patient with their different ways of thinking and behaving. For example, if they don't understand human emotions like love in the same way, she has to patiently explain it to them.