Another theme could be exploring alternative relationships for the other characters without Yuki's interference. So, the fanfiction might focus on how other characters' storylines develop when Yuki is not in the picture in a positive way as she was originally.
There could also be authors who are more interested in creating drama and conflict. Bashing Yuki can create a lot of drama within the story, as she is a central character in 'Vampire Knight'. So, they use her as a tool to generate more interesting and controversial storylines.
In many of these fanfictions, a common theme is the reaction of the vampire society to Yuki's pregnancy. Since vampires have different values and traditions compared to humans, this can create a lot of interesting plot twists. Another theme could be Yuki's struggle to adapt to her new situation while still being involved in the power struggles and secrets within the Vampire Knight world. Some fanfictions also explore how her pregnancy might change the power balance among the different factions in the story.
The theme of identity is also prevalent. Zero is constantly trying to figure out who he is now that he is part vampire. Yuki too has an identity crisis as she is caught between the human and vampire worlds. Fanfictions often delve into how they come to terms with their new identities, whether they accept them or try to change them, and how it affects their relationship with each other and those around them.
A common theme is the exploration of unrequited love. Since Yuki has complex relationships with other characters in the original Vampire Knight story, fanfictions often play with the idea of Hanabusa loving Yuki from afar while she is preoccupied with others. This creates a lot of emotional tension.
One common theme is the love triangle between Zero, Yuki, and Kaname. Many fanfictions explore how Zero and Yuki's relationship develops in the midst of this complex situation.
Common themes in Yuki x Zero fanfiction include their emotional connection. Despite their differences, they have a deep emotional bond. There's also the theme of self - discovery. Through their relationship, both Yuki and Zero can learn more about themselves. For example, Zero may discover a softer side of himself because of Yuki, and Yuki may find more strength in her identity through her connection with Zero.
One popular theme is the complex relationship between Yuki and Zero. Their relationship is filled with tension, as Zero is a vampire hunter and Yuki has a connection to the vampire world. Another theme could be Yuki's struggle with her identity, being caught between the human and vampire worlds.
One common element is the exploration of Yuki's dual nature. The OC often interacts with Yuki in a way that either emphasizes or challenges her vampire - human duality. Another element is the setting of Cross Academy. The fanfictions usually keep the school as the main backdrop for the interactions between the OC and Yuki.
The themes usually revolve around their relationship. One is the theme of protection. Kaname is always very protective of Yuki, and this is often explored in fanfics. Another is the theme of discovery. Yuki discovers more about herself and her feelings for Kaname as the story progresses. And there's also the theme of forbidden love. Since their relationship is complex due to their different species, this adds an element of the forbidden which is a common theme in many fanfics.
In some cases, the Yuki OC fanfiction can be a form of self - insertion for the writer. They create an OC that they can project their own feelings and experiences onto. This can lead to very emotional and personal stories that might explore themes like love, friendship, and self - discovery in the context of the Vampire Knight universe.