A common theme is the power dynamic. Klaus is a powerful character, and exploring how the oc wife fits into that power structure, whether she challenges it or submits to it in some ways. Another theme is love against all odds. Given Klaus's nature, it's often about how their love overcomes his dark side and the obstacles in their world.
One theme that frequently shows up is the oc wife's discovery of Klaus's true nature. It could be a slow realization or a sudden shock, and then how she copes with it. Also, family acceptance is a theme. How does Klaus's family accept or not accept the oc wife? And vice versa, how does the oc wife interact with his family members? There are often a lot of emotional and relationship - based themes in these fanfictions.
One common theme is friendship. Often, the oc forms a deep and unexpected friendship with Klaus. Another theme is redemption. The oc might be involved in Klaus's journey towards redemption. For example, in some fanfictions, the oc helps Klaus face his past wrongs.
A sense of identity is a big theme as well. Growing up as Klaus's daughter, she has to figure out who she is on her own. Is she just defined by her father? Or does she create her own identity? These are the kinds of questions that are often explored in this type of fanfiction, which makes it really engaging for readers who are interested in character - driven stories.
Love is a very common theme. The love between Klaus and the OC is often explored, especially how it deepens with the arrival of a baby. It's about their journey of falling in love all over again as they take on the role of parents.
Another theme might be Klaus's reaction to the pregnancy. Some fictions explore whether he is protective, indifferent, or even hostile at first. His complex character adds a lot of depth to this kind of storyline.
One common theme is the struggle for acceptance. The OC daughter often has to deal with Klaus's complex personality and the whole vampire - werewolf - witch world she's born into. Another theme is family loyalty. Despite the challenges, she usually shows great loyalty to Klaus and the rest of the Mikaelson family.
One common theme is the discovery of love. Usually, the OC and Loki start off in a somewhat unexpected way, like in a situation where they initially clash but then gradually fall in love. For example, they might meet during a battle or a political intrigue in Asgard.
One common theme is the power of love to change Loki. In many of these fanfictions, the OC's love helps Loki to become a better version of himself, or at least to see things from a different perspective.
One common theme is the exploration of a complex relationship. Since Hannibal has such a dark and intricate personality, how his oc wife deals with that is often explored. For example, themes of love and fear in the relationship.
Another common theme is the adjustment to the Naruto world. Since the oc wife is an original creation, she has to adapt to the unique culture, powers, and politics of the Naruto universe. This often creates interesting plotlines as she tries to fit in while also being with Sasuke.
One common theme is the struggle of maintaining a relationship in the face of Batman's secret identity. The oc wife often has to deal with his disappearances and the secrecy.