Another theme is sacrifice. Stefan, being the self - sacrificing type, is often shown making great sacrifices for Elena's safety or happiness. This could be giving up his own powers, or facing off against powerful enemies. In some fanfictions, Elena also makes sacrifices for Stefan, showing the depth of their mutual love.
One common theme is the idea of eternal love. Since they are in a supernatural world, their love is often depicted as something that can transcend time and death. For example, in many fanfictions, even if one of them is in danger or seemingly lost, their love remains unwavering.
Love and commitment are very common themes. Since they are married, the fanfictions often explore how they stay true to each other in the face of various difficulties. For example, in many stories, they have to deal with threats from other supernatural beings but their love remains unshaken.
Another theme is the development of characters' emotions over time. As Stefan navigates his love for the two, we see how Elena and Caroline also grow and change in their relationships with him and with each other. For example, in some fanfictions, they might start off as rivals but end up as friends who understand each other's connection to Stefan.
Love and passion are common themes. Writers often focus on the intense emotions that Stefan and Elena have for each other. Another theme could be redemption. Maybe one of them has made mistakes in the past and through their love, they find a way to redeem themselves.
Love and sacrifice are also common themes. Stefan and Damon both love Elena deeply and are willing to make sacrifices for her. This could range from giving up their own power to save her life. And there's also the theme of redemption. Damon, who has a darker past, might be on a path of redemption because of Elena's influence. He tries to be a better person, which creates an interesting dynamic in the fanfics.
There are also fanfictions that focus on the power dynamics between them. As a vampire, Stefan has certain powers, and how that affects their relationship, whether it creates a sense of imbalance or a unique bond, is explored. For instance, Stefan's ability to protect Elena with his vampire strength can be a central plot point in some fanfictions.
One common theme is redemption. Fanfictions often explore Stefan's journey of redemption in relation to Elena, especially considering his past as a vampire with a dark history. For example, in some stories, he tries to make up for his past mistakes to be worthy of Elena's love.
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.
Another theme might be about their self - discovery journey. They both have complex identities, and a fanfiction could explore how they help each other understand their true selves better, whether it's Stefan coming to terms with his Ripper side or Elena understanding her role as a doppelganger in a new way.
I'm sorry, I haven't read this specific fanfiction. But you can try to find it on popular fanfiction websites like Archive of Our Own or Fanfiction.net.
One possibility is that Stefan is under some dark spell or influenced by an evil force. Maybe he kidnaps Elena to protect her from a greater danger that he believes only he can handle, but his actions are misinterpreted. For example, there could be a new vampire hunter in town who has a special weapon that can kill vampires instantly, and Stefan thinks the only way to keep Elena safe is to take her to a hidden location.