Survival is another theme. Since they are often in a difficult world setting, their fight for survival together and how that impacts their relationship is a key aspect in many Mika x Yuu fanfics. In some stories, they have to rely on each other against powerful enemies and harsh environments.
The theme of sacrifice also appears often. Mika might be willing to sacrifice anything and anyone for Yuu's sake. This shows the depth of his yandere - like love. Additionally, there's the theme of internal conflict. Yuu may struggle with his feelings towards Mika, as he has to deal with Mika's over - the - top behavior while also having his own emotions for Mika.
One common theme is the struggle between their different natures. Since Yuu is a demon and Mika is a vampire, there's often a conflict and a need to overcome their natural instincts to be together.
Another theme is sacrifice. In many fanfictions, either Mika or Yuu is willing to sacrifice themselves for the other's well - being. For example, they might put themselves in danger to protect the other from harm.
One common theme might be the relationship between Mika and Yuu, exploring their deep connection and how they interact with each other in different situations.
One common theme is possessiveness. As Mika is the yandere in this pairing, he often shows extreme possessiveness over Yuu. He doesn't like Yuu being close to others and will go to great lengths to keep Yuu to himself.
One common theme is loyalty. Mika's possessiveness can be seen as an extreme form of loyalty towards Yuu. Another theme is protection. Since Mika is possessive, he often tries to protect Yuu from any harm. And there's also the theme of jealousy. If other characters get too close to Yuu, Mika's possessive nature will make him jealous.
The theme of redemption is also common. If Mika has done something he regrets, Yuu might be the one to help him find redemption. Or vice versa. This theme gives a sense of growth and development to their relationship, making it more than just a simple love story. It shows that they can help each other become better versions of themselves.
I don't really support or promote lemon fanfiction due to its often inappropriate nature. But generally, in non - appropriate fanfictions, common themes might be about their relationship dynamics in an overly sexualized way which is not suitable for public discussion.
One popular 'yuu x mika fanfic' might be the ones that explore their relationship in a post - apocalyptic setting. It could show how they rely on each other for survival and how their bond deepens over time.
Another theme is growth. They both grow as characters through their relationship. Yuu might become more confident with Asuramaru's support, and Asuramaru may learn more about humanity. This is often shown in fanfics where they face challenges together and come out stronger on the other side. The growth can be emotional, mental, or even in terms of their powers. It's really interesting to see how different authors explore this aspect of their relationship.