The fanfiction deviates significantly. In the original, Bella's feelings for the Cullens are mostly positive or at least intrigued. However, in this fanfiction, her hatred might stem from different plot developments. For example, in the original, the Cullens are presented as somewhat heroic and mysterious in a positive way. But in the fanfiction, new events could be introduced that make Bella see them in a bad light, like they might be involved in some sort of unethical activities that change her perception completely.
In the original Twilight story, Bella is initially attracted to the Cullens, especially Edward. But in this fanfiction where she starts to hate them, it's a complete contrast. It shows a different side of Bella's character, one that is more critical and less forgiving. In the original, she is more likely to overlook their flaws because of her love for Edward. Here, she focuses on the negative aspects.
In the original 'Twilight' story, Bella is in love with Edward and her relationship with Jacob is more of a complex friendship. So, this fanfiction completely changes the nature of those relationships by introducing the idea of cheating. It goes against the moral and relationship framework established in the original.
In the original Twilight story, Bella has a main relationship with Edward and Jacob, and the idea of the whole pack imprinting on her is completely new. It deviates by adding a whole new level of complexity to Bella's relationships. Instead of just having the love triangle situation, she now has a connection with multiple members of the pack.
The original series focuses on the love story between Bella and Edward and the family dynamics within the Cullens. The 'Rosalie Kills Bella' fanfiction completely changes the narrative by introducing a very different kind of conflict. It takes away the central love story aspect and replaces it with a more sinister plotline. Rosalie's character in the original is complex but not murderous towards Bella, while the fanfiction rewrites her in a more extreme way.
Well, it could be due to the way the Cullens interact with the other people in Forks. If Bella notices that they are being manipulative or using their powers in a way that she doesn't like to influence the townspeople, that could make her start to hate them. Also, if there is some kind of power struggle within the Cullen family that starts to affect Bella negatively, like she gets caught in the middle of it or she sees how it's causing harm to those she cares about, she might turn against them.
The original 'Twilight' has Bella in a relationship with Edward and having a different kind of future. In this fanfiction, the relationship with Jacob changes the whole trajectory. Instead of the vampire - human relationship as the central focus, it's now a werewolf - human relationship that leads to pregnancy, which is a huge deviation.
In the original Twilight plot, Bella is a normal human who becomes a vampire. With Bella having wings in the fanfiction, it could change the whole dynamic of her relationships. For example, Edward might be more protective of her because of this new and potentially dangerous aspect of her. Also, her interactions with other vampires and werewolves would be different. She could use her wings to escape or attack, which is not something in the original plot.
In the original Twilight, Bella is a normal human girl. But in 'bella witch twilight fanfiction', she has witch powers. This completely changes the dynamic. For example, instead of always being the damsel in distress, she can be a powerful force. She can use magic to fight off enemies rather than relying on the Cullens all the time.
In some fanfictions, the Cullens might hate Bella because of jealousy. Maybe other vampires are jealous of the attention she gets from Edward. Another reason could be that she brings too much danger to their family. Her presence could attract unwanted attention from other vampires or vampire hunters, which puts the Cullens at risk.
In the original Twilight series, Bella doesn't have cancer. So, in 'bella cancer twilight fanfiction', there is an added element of mortality and human vulnerability. It changes the dynamic of her relationship with Edward as they face a very real and often fatal human illness.
The fanfiction might deviate from the original by focusing on their married life more intensely. In the original Twilight, a lot of the story was about their courtship and the challenges they faced getting together. In 'the perfect wife' fanfic, it could be about how they make their marriage work. There might be new characters introduced who are part of their married life, like vampire neighbors or family members that we didn't see much in the original.