Maybe the OC is a descendant of an ancient race that was once closely associated with the power of Divine Dividing. They come to the high school to find out more about their heritage and end up getting involved in the power struggles between the different factions in the DxD world. This could involve making alliances and enemies along the way.
Another fanfiction concept could be that the OC has a unique form of the Divine Dividing that doesn't just split power but also can split time or space in a limited way. This would make them a very interesting character as they try to figure out how to use this power for good while also keeping it a secret from those who might misuse it.
The OC's abilities related to Divine Dividing could be developed in different ways. They could start with basic power - splitting physical objects. As the story progresses, they learn to split intangible things like magical barriers or even the auras of other powerful beings. This growth in power can be tied to their emotional and mental development throughout the fanfiction.
One idea could be to create an OC who has a Sharingan that has unique abilities. For example, instead of just the normal powers like predicting movements, it could have the ability to see through illusions created by devils in the Highschool DxD universe. The character could be a transfer student, perhaps from a hidden clan that has a connection to both the Naruto world (where Sharingan is from) and the Highschool DxD world. Their backstory could involve some sort of experiment or curse that led to them having the Sharingan.
One idea could be that the OC with the Vritra Gear has to hide its true power at first. Maybe they are new to the school and don't want to draw too much attention. As the story progresses, they gradually reveal their abilities during battles against other supernatural beings.
You could write about an OC who is a half - angel, half - devil. Their internal struggle between the two natures and how they fit into the world of Highschool Dxd, trying to find their place among the devils, angels and fallen angels. It could explore themes of identity and acceptance.
An interesting OC for a Highschool DxD fanfiction could be a half - angel, half - devil. Their internal struggle between the two natures would make for a great character arc. They could be trying to find their place in the world where angels and devils have their own agendas, and they don't fully belong to either side.
A good plot idea could be that the OC Dragon God has to hide their true identity in the high school. They are there to find a certain magical item that is hidden in the school. As they search, they get involved with the main characters and have to deal with the normal high school drama as well as the supernatural threats that come their way.
An OC (Original Character) in a Highschool DxD fanfiction having the Rinnegan could be an extremely powerful and unique addition. The Rinnegan, from the Naruto universe, brings a whole set of abilities like the Six Paths powers. In the context of Highschool DxD, this OC could use these powers in various ways. For example, the ability to see chakra could be translated into seeing the magical energy in the DxD world. They could use the gravitational powers of the Rinnegan to manipulate the environment during battles against devils, angels, or fallen angels. It would make for a very interesting and overpowered character in the Highschool DxD fanfiction setting.
Well, you could create an OC that has the power of prophecy. This OC in the 'Highschool DxD' fanfiction would know about future events and could either try to prevent disasters or manipulate them to their advantage. Maybe the OC is a godlike figure who comes from a different dimension where the rules of power are much different. They introduce new forms of magic or combat techniques that the characters in Highschool DxD have never seen before.
One idea could be creating an OC who has a unique power related to time manipulation. This OC could use their power to turn back time during battles in the 'Highschool DxD' universe, catching opponents off - guard. Another idea is an OC with a power based on sound. They could use sonic waves for offense and defense, like creating a sonic shield or a powerful sonic blast.
Well, for creating an OC (Original Character) as a Dragon God in a Highschool DxD fanfiction, first think about their powers. A Dragon God could have the power of elemental manipulation, like controlling fire or ice. Their appearance could be a mix of human and dragon features. Maybe they have dragon wings that can be hidden at will. Another important aspect is their backstory. They could be an ancient being that has just awakened in the modern Highschool DxD world.