Well, a prevalent theme is the idea of fate and how they are drawn to each other despite all the odds. Also, the theme of secrecy and the forbidden love aspect is quite common. Since Elena is part of the Mystic Falls gang and Klaus is an enemy in many ways, hiding their relationship from others is often explored in these fanfictions. And of course, there's the theme of sacrifice, where either Elena or Klaus has to sacrifice something for their love.
In Vampire Diaries Elena and Klaus love fanfiction, a common theme is power dynamics. Klaus is extremely powerful, and Elena is a human - turned - vampire. How this power imbalance affects their relationship is often delved into. Additionally, the theme of loyalty comes up a lot. Elena has loyalty to her friends in Mystic Falls, and Klaus has his own loyalties to his family. How these loyalties clash or are reconciled in the context of their love is a popular theme.
Sure. A lot of fans have written great fanfictions about Elena and Klaus' love. Some focus on the forbidden aspect of their relationship, like how Elena is supposed to be with the Salvatore brothers but has this unexpected connection with Klaus. It adds a new layer of drama and romance to the Vampire Diaries world.
There are fanfictions where Elena and Klaus are thrown into an alternate universe. In this universe, they are the only two vampires left and have to figure out how to survive and repopulate the vampire race. This forces them to work together closely and, over time, they develop feelings for each other that are far from the hatred they initially had in the original Vampire Diaries storyline.
One idea could be that Klaus, after being away for a long time, returns to Mystic Falls and finds Elena in a difficult situation. He decides to help her out of a sense of an old, unspoken connection. As they spend time together, they start to understand each other better and a relationship begins to form.
Love is also a common theme. It could be romantic love for her character or platonic love within the family. In some fanfictions, Klaus's sister falls in love with a character from the show, and this love story is intertwined with her relationship with Klaus. For instance, in 'Love and Blood', her love interest is a werewolf, which creates a lot of drama considering the vampire - werewolf dynamic in the Vampire Diaries.
One common theme is the power dynamic. Kol is an ancient and powerful vampire, while Elena is a human - turned - vampire with her own strength. Another theme is the exploration of the unknown. Since Kol has a different personality compared to the other vampires Elena has interacted with, it's like she's stepping into uncharted territory with him. Also, redemption can be a theme, as Kol might seek redemption through his relationship with Elena, or Elena might see the potential for good in Kol.
One common theme is friendship. Since they were friends before any romantic feelings came into play, many fanfictions explore how that strong friendship foundation can either support or complicate a romantic relationship between them.
One common theme could be her struggle with PTSD. After the abuse, Elena might constantly relive the trauma, which could be shown through nightmares or flashbacks. Another theme could be her isolation. She may push away her friends, like Stefan and Damon, because she doesn't want them to see her as weak or damaged. Also, there could be a theme of revenge. Elena might seek to get back at her abuser in some way, either through direct confrontation or more devious means.
One common theme is protection. Alaric often acts as a protector figure for Elena in fanfiction, much like he did in the show. Another theme is mentorship, as Alaric can be seen guiding Elena through the complex world of the supernatural.
One common theme is the reaction of her love interests. For example, Damon might become extremely protective and vengeful when Elena is hurt. Another theme is her own strength in the face of pain. She often has to dig deep within herself to survive the injury.
One common theme could be criticizing Elena's actions regarding her relationships. For example, some fanfictions might bash her for being indecisive between Stefan and Damon. Another theme could be her role in the supernatural events in Mystic Falls. Maybe she's seen as too self - centered in some stories, always putting her own needs and desires above others when it comes to dealing with vampires, werewolves and witches. Also, her character development might be a target, with fanfictions suggesting she didn't grow or change in a positive way as the series progressed.