She could initially be angry and feel betrayed. Elena might try to win Damon back at first, thinking it's a mistake. But as time goes on, she might realize that Damon's choice was based on something real and start to accept it, while also going through a process of self - discovery to figure out who she is without Damon.
Elena might be heartbroken. She probably expected Damon to always be there for her, so his choice of Bonnie would come as a shock.
One possible reason could be that Bonnie has a unique strength and independence. She's a powerful witch, and Damon might be attracted to that power. Also, Bonnie has always been there for him in tough situations, more so than Elena in some ways.
This change would also have an impact on the other characters. Stefan, for example, might be caught in the middle. He has his own relationship with Damon and also cares about Elena. The fanfiction could create a whole new set of alliances and rivalries. Characters from the 'Twilight' series might also be involved in some way, further complicating the relationships. Overall, it would be a big upheaval in the existing relationship dynamics.
One possible reason could be that Bella has a certain allure or mystery that Damon finds more captivating than Elena. Maybe Bella represents a new and different kind of challenge for him.
Elena would probably be terrified at first. She's a human in a world full of powerful supernatural beings. Being kidnapped by Damon would mean she's in a very vulnerable position. She might initially try to fight back or escape, using any opportunity that presents itself.
She could be terrified at first. After all, Klaus is a very powerful and dangerous vampire. But Elena is also a strong - willed character. So she might quickly gather her courage and start looking for ways to escape.
Their relationship becomes more serious and committed. With a baby on the way, they have to think about more than just themselves.
Damon might initially be shocked and angry. He has always had feelings for Elena, and seeing Stefan marry both her and Caroline could make him feel betrayed. He might lash out and try to cause trouble for their relationship at first.
Stefan would be extremely worried and angry. As Elena's other love interest, he has a deep connection with her. He would immediately start looking for her, using all his vampire skills and resources. He would probably suspect Damon right away, given their history of rivalry over Elena.
Elena might show her jealousy by being overly critical of Bella. For example, she could constantly find fault in Bella's actions or decisions in the fanfiction.
Elena would likely be angry. She has her own agency and doesn't like being controlled. If Stefan kidnapped her, she would fight back. She might use her knowledge of the supernatural world and her relationships with other characters to try to escape. For example, she could try to call out to Damon telepathically if they have some sort of connection in the story.