One common theme is the relationship between Serafall and other characters from the series. This could be her interactions with the main protagonist or other devils. Another theme is her power and how it's portrayed in different storylines. Sometimes, there are also themes related to her role in the devil society and how she might change or influence it in the fanfictions.
Love and relationships can be a theme as well. Whether it's a platonic love among friends or a more romantic interest, it often plays a role in the fanfiction. Sometimes Serafall might have a crush on another character or be the object of someone else's affection, which can lead to all sorts of interesting storylines.
Serafall herself has a unique personality. She's cute and powerful at the same time. Fanfiction writers can develop her character further, for example, by exploring her relationships with other characters in more depth. This makes the fanfictions about her very appealing to readers.
There might be a fanfiction where Issei accidentally stumbles into one of Serafall's secret training grounds. Serafall is initially angry but then realizes Issei's potential. She decides to train him in some unique devil magic. This leads to a series of comical and at the same time, character - building events as Issei tries to master the new skills while dealing with Serafall's unpredictable nature.
Romance is a huge theme as well. It could be between a Shinto - inspired character and one of the main characters from Highschool DxD. For example, a love story between a kitsune (a common Shinto - related creature in fanfictions) and Issei. The cultural differences between Shinto and the other elements in the story can add an interesting dynamic to the romantic relationships.
One common theme is her growth and development. Since she is a strong character in the series, fanfictions often explore how she can become even more powerful or gain new abilities. Another theme is relationships. This could be her relationships with other characters from the show, like forming new friendships or even romantic relationships.
Another theme is her growth in power. Many fanfictions explore how Asia becomes stronger and how that affects her relationships with other characters like Issei. For example, in some stories, as she gains power, she also gains more confidence and is able to stand up for herself more. It's really interesting to see how her character develops in different ways in these fan - created stories.
One common theme is power. Ophis being a very powerful character, many fanfictions explore how her power is perceived and used in different situations within the high school setting.
One common theme is family loyalty. Since the Sitri family is an important part of the Highschool DxD universe, many fanfictions explore the bonds and loyalty within the family. For example, a Sitri character might go to great lengths to protect their family's honor or secrets.
One common theme is power - up. Siegfried is often depicted as getting stronger or unlocking new abilities. This ties in with the overall power - fantasy aspect of the Highschool DxD universe.
Power - up themes are common. The Juggernaut is a very powerful entity in the Highschool DxD universe in fanfictions. So often the stories revolve around the protagonist either obtaining Juggernaut - like powers or using Juggernaut powers in new and exciting ways.