One possible plot could be that Klaus believes Bonnie has the key to a powerful spell that could help him gain ultimate power. So he kidnaps her. He whisks her away to a remote island. There, he tries to persuade her to help him, using both threats and false promises. He might start off being cruel but then gradually start to have some strange respect for her as she resists him.
Maybe Damon could save her. He's always been protective of those he cares about and he's not afraid to take on Klaus.
Another plot twist might be that Klaus was forced to kidnap his mate by an external force, like a more powerful enemy who threatened Klaus's life or the lives of his loved ones if he didn't. This would add a layer of complexity to Klaus's actions and make the readers re - evaluate their initial perception of him as a simple kidnapper.
Well, one possibility is that Elena's friends would immediately start a search party. Damon, for instance, would be furious and stop at nothing to find her. He might enlist the help of Stefan and Bonnie. They could use Bonnie's magic to try and track Klaus' whereabouts.
The baby could also have a special connection to the spirit world. Bonnie, with her witch powers, and Klaus, with his long and complex history, could find themselves on a journey to understand this connection. They might meet different spirits who either offer guidance or pose a danger to the baby as it grows up.
Well, a possible plot could be that they marry as a political move in the supernatural world. Klaus, being a powerful vampire, and Bonnie, a strong witch, their union could shift the power balance. Then, they might face challenges from other supernatural factions who oppose their union. Also, a plot where they get married due to a magical bond that was accidentally created, and they have to figure out how to make their relationship work while dealing with their own personal issues and the reactions of their families and friends.
Elijah could be on their side. He is Klaus' brother and might understand the importance of the baby, especially if he sees it as a way to keep Klaus in line or to bring about a new era of peace among the different supernatural species. He could use his diplomatic skills to protect the baby from threats.
I'm not sure specifically as it depends on the particular fanfiction. It could be a story where a character named Kol kidnaps Bonnie within the universe of the show or book that the fanfiction is based on. Maybe it's part of a complex plot involving magic, power struggles, or personal vendettas.
One plot idea could be that Bonnie and Klaus travel back to a time when the Original family was first created. They could witness the making of the first vampires and how it all started. This would give them a chance to change certain things that might affect the present they come from.
This type of fanfiction often dives into the psychological aspects of the characters. The kidnapped mate may experience a range of emotions such as fear, anger, and confusion at first. As the story progresses, they might start to see Klaus in a different light. The writer could also introduce other characters who react to this situation, either trying to rescue the mate or siding with Klaus, which adds more layers to the story.
Another theme is the protection of the unborn child. Given the dangerous supernatural world they live in, both Bonnie and Klaus are usually depicted as being extremely protective. They will go to great lengths to keep their baby safe from all the threats out there.