Family dynamics is another key theme. There are often struggles and joys within the new family structure. The OC might have to deal with Klaus's complex family history and how it impacts their new family with the baby.
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.
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 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 common theme is family. Since Klaus comes from a complex family in the Vampire Diaries universe, many fanfics about baby Klaus explore his family relationships. Another theme is his emerging powers. Writers often like to play with how his powers might have started to show when he was a baby.
One common theme could be protection. With Klaus being a powerful but also very much hunted character, protecting the baby from his enemies would be crucial. Another theme might be family. How the baby fits into the already complex family structure of the Originals.
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 love. The love between Legolas and the OC is central, and it extends to their love for their baby. It shows how their relationship grows stronger with the addition of the new family member.
Often, there could be a plot about protecting the baby. Klaus, with his complex past and many enemies, would need to keep the baby safe from those who might want to harm it to get to him.
A theme that frequently shows up is redemption. Klaus, being a complex and often villainous character, may be on a path to redemption in some fanfictions, with Stefan either helping or hindering. Also, power dynamics play a role. Klaus is very powerful, and Stefan has his own set of abilities, so how they interact in terms of power is a common theme. For example, in some stories, Stefan has to find ways to level the playing field when dealing with Klaus.
One common theme is redemption. When Klaus is hurt, it can be a starting point for him to seek redemption for his past wrongs. Another theme is vulnerability. It shows a side of Klaus that we don't always see, as he's usually portrayed as strong. For example, in some fanfictions, his hurt might make him more open to forming new relationships or mending old ones.