She could also try to reason with Kai. Elena is a smart and empathetic character, so she might try to understand his motives and use that to her advantage to get free. For example, if Kai has some sort of vendetta against her friends, she could offer an alternative solution to whatever problem he has.
Elena would probably be terrified at first. She might try to fight back or escape immediately. After all, Kai has a reputation for being dangerous.
Over time, if she realizes that Kai isn't going to harm her right away, Elena might become more defiant. She would use her wits to try and outsmart Kai, constantly looking for weaknesses in his plan or his character. And she would never stop thinking about how to get back to her friends and loved ones.
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.
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.
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 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.
The Salvatore brothers, Stefan and Damon, are the most likely candidates. They both have a strong connection to Elena and would stop at nothing to rescue her. Stefan's sense of chivalry and Damon's fierce protectiveness would drive them to track down Katherine and get Elena back.
She's likely to be defiant at first. Elena has a strong will, so she would probably resist Klaus's orders and try to escape.
Elena might be heartbroken. She probably expected Damon to always be there for her, so his choice of Bonnie would come as a shock.
Elena's friends and family might be a bit wary at first. After all, Elijah is from a different world. Her aunt Jenna might be concerned about the implications of this marriage for Elena's future. However, her friends like Bonnie and Caroline could come around once they see how much Elijah loves Elena. For Elijah's family, some might be happy to see him find love, while others, who are more traditional or power - hungry, might see Elena as an outsider and try to break them up.
The Salvatores would probably be shocked. Damon might be initially angry, thinking Elijah has taken advantage of Elena. Stefan, on the other hand, would be more concerned about Elena's well - being and the implications of a half - vampire, half - something - else baby. He'd want to make sure she's safe.
Their friends might be shocked at first. Damon, for example, might be a bit jealous as he had feelings for Elena in the past. But he would also probably be protective. Bonnie would likely use her magic to ensure the pregnancy goes smoothly and help protect Elena from any supernatural threats. Stefan would be supportive, seeing it as a new chapter in Elena's life.