Bella would be heartbroken. She has put so much trust in Edward, and this act of cheating would make her question everything. She might become angry and lash out at both Edward and Tanya. She could also become very sad and isolate herself from others.
There might be some very inappropriate and non - canonical fan - created works out there that might have such disturbing content, but it's not something that should be promoted. The Twilight saga is known for its vampire - human love story, not this kind of improper relationship.
One interesting Bella Twilight fanfic could be one that explores Bella's life if she had different vampire powers. For example, instead of the typical vampire abilities in the original story, she might have the power to control the elements, which would completely change the dynamic of her relationships with Edward and the other vampires. Another could be a fanfic that focuses on Bella's friendship with Jacob from a different angle, like if they had met under different circumstances before the events of the main story.
In such a fanfiction, it could change the entire dynamic of Bella's relationship with the other characters. Maybe she'd be more confident and powerful from the start.
Well, she might face a late fee first of all. The water company could send her a warning notice. And it could also cause some inconvenience in her daily life, like not being able to use water properly for things like taking a bath or washing dishes. In the context of the Twilight fanfic, it could add an element of chaos to her already complex life among vampires and werewolves.
A major theme is the idea of breaking away from the expected. In the Twilight series, Bella's relationships were mostly centered around Edward and Jacob. In fanfictions with Garrett, it's about her branching out. Also, there's often a theme of self - discovery. As Bella interacts with Garrett, she discovers new sides of herself. This can be seen in many such fanfictions where their conversations or experiences lead Bella to reevaluate her beliefs and desires. For example, in some fics, Garrett introduces Bella to a different vampire culture, which makes her question her understanding of vampires in general.
Another one might be 'The Alternate Bella in Twilight'. Here, the OC Bella could interact with the other characters in unique ways. Maybe she forms different relationships with Edward, Jacob, or the other vampires and werewolves. It's interesting to see how the author weaves a new narrative while still keeping the essence of the Twilight world.