There is also 'OC's Adventure in Highschool DxD'. This story stands out because the OC is not just a bystander but actively changes the course of events in the Highschool DxD world. It has exciting plot twists and the development of the OC's powers over time is really fascinating.
Well, some storylines involve the OC dragon having a special bond with one of the main characters from Highschool DxD. This bond could be based on a shared goal, like finding a powerful artifact that is important to both the dragon and the character. It could also be a more emotional bond, like the OC dragon helping a character through a difficult time. There are also storylines where the OC dragon is an outcast from their own dragon clan and has to prove themselves in the world of Highschool DxD.
In Highschool DxD OC fanfiction, the 'Power - Up' trope is quite common. Your OC starts with a certain level of power and then, through training, battles, or special encounters, they gain more power and become stronger. The 'Redemption' trope can also be used. If your OC has made mistakes in the past or has a dark history, they can strive to redeem themselves throughout the story. Also, the 'Chosen One' trope works well. Your OC could be the one chosen to save the supernatural world from a great threat, like an impending war between devils, angels, and fallen angels. This gives them a sense of purpose and importance in the story.
One popular Highschool DxD fanfiction might be those that explore the different relationships between the characters in new and interesting ways. For example, some fanfictions could focus on the growth of Issei's character outside of the main plot events of the original work.
One popular fanfiction might be those that explore Vali's backstory more in - depth. For example, stories could detail his training and how he became so powerful.
In these fanfictions, the 'loner - with - a - heart - of - gold' trope is seen a lot. The OC mercenary acts tough and independent on the outside but has a kind heart deep down. The 'rivalry' trope is another one. They might have a rivalry with another character, which could be over power, status, or a love interest. And the 'hidden - potential' trope is also popular. The mercenary initially seems like an ordinary fighter but then reveals amazing hidden powers as the story progresses.
A great trope is the 'unexpected power - up'. Your female OC might be in a difficult situation, and suddenly, she discovers a new power within herself that helps her turn the tables. The 'protector' trope is also good. She feels the need to protect someone or something in the Highschool DxD world, like a group of innocent humans or a sacred place. And the 'identity crisis' trope can add an interesting layer to her character. She might be confused about whether she belongs to the devil side or the angel side, or something else entirely, and this internal struggle can drive the story forward.
One interesting 'oc x highschool dxd fanfiction' story could be about an OC who is a transfer student with a mysterious power. They quickly become involved with the main characters from Highschool DxD. Their power might attract the attention of the devils and angels in the story, leading to all sorts of adventures and challenges.
One interesting story could be about an OC who has a unique power that helps the Gremory group in a new and unexpected way. For example, an OC with the power to manipulate time slightly, which they use to gain an edge in battles against their enemies.
Some 'oc the gamer highschool dxd fanfiction' focus on the relationships the OC forms. Since they come from a 'gamer' background, they might approach relationships in a different way compared to the regular characters in High School DxD. This can lead to some really interesting character dynamics and story developments.
One popular 'highschool dxd diablo fanfiction' story could be one where Diablo's powers are incorporated into the High School DxD universe in a unique way. For example, he might use his demonic powers to help the main characters in High School DxD overcome a powerful enemy. However, it really depends on different authors' creativity.