One common theme is loyalty. Both Levi and Mikasa are extremely loyal characters in the original story, and this is often explored further in fanfics. For example, they might show loyalty to each other in ways that weren't shown in the original series.
Survival is another theme. Given the post - apocalyptic setting of their world, many fanfics will center around them trying to survive together. They use their skills, Levi's combat expertise and Mikasa's strength, to get through various hardships.
One common theme is trust. Given their respective personalities, they both have to learn to trust each other in many fanfictions. For example, in stories where they are on a dangerous mission together, they need to trust the other's combat skills and decision - making abilities.
A common theme is loyalty. Both Mikasa and Levi are known for their loyalty in the original story, and in fanfictions, this loyalty often extends to their relationship with each other, whether it's loyalty on the battlefield or in more personal situations.
Well, family and future are often themes. They have to think about how to raise the child in a world filled with threats. Also, there might be a theme of hope. The pregnancy could symbolize a new beginning and hope for a better future in a rather gloomy world they live in.
One common theme is the exploration of their mutual respect. They both have strong personalities and in fanfictions, it's often shown how they come to respect each other's skills and decisions more deeply.
One common theme is 'Overcoming Trauma'. Both Levi and Mikasa have had difficult pasts, and in many fanfictions, their love helps them heal from their traumas. For example, they might find comfort in each other after a particularly tough battle.
One common theme is friendship. Despite their different backgrounds and personalities, they form strong bonds. For example, in many fanfics, they rely on each other during battles.
One common theme is family. The appearance of a baby makes Levi and Mikasa form a sort of family unit, and the fanfictions explore how they adapt to this new family dynamic.
Another theme is the fight against evil. Just like in the original Levi and Mikasa story and in Harry Potter, they are often pitted against dark forces. This theme of good vs. evil shows how they use their unique skills and abilities, a combination of their original and newfound magical powers, to protect Hogwarts and its inhabitants.
One common theme is growth. It shows how Mikasa grew from a child into the strong character she is. Another theme is family. Her family's influence on her as a child is often explored. For example, how her parents' teachings stayed with her.
Another theme is self - discovery. In some fanfics, both Christa and Mikasa go through a journey of understanding themselves better while being in each other's company. For example, they might learn about their own strengths and weaknesses through the experiences they share in the fanfic.