First, give your OC a unique backstory related to the Red Dragon Emperor power. Maybe they didn't inherit it in the traditional way, or there was some sort of prophecy involved. Second, define their personality traits clearly. Are they more hot - headed like Issei in some ways, or are they calmer and more calculating? Third, think about their goals. It could be something as simple as becoming the strongest in the school or something more complex like uniting all the different supernatural races. And don't forget to give them some flaws, like being overly confident at times which can get them into trouble.
One popular storyline could be the OC's struggle to control the power of the Red Dragon Emperor. For example, they might face challenges in taming the intense and sometimes uncontrollable power within them. Another could be their relationships with the existing characters from Highschool DxD. They might form alliances or rivalries with Rias and her peerage. Also, a story could revolve around the OC uncovering secrets related to the Red Dragon Emperor heritage that were previously unknown, leading to new adventures and battles.
Well, a fanfiction like this often delves into the lore of the White Dragon Emperor more deeply. Maybe it gives a backstory to some of his powers that the original series didn't fully explore. The OC in it could be a catalyst for change in the 'Highschool DxD' world. It could be a character from a different faction who comes to understand the White Dragon Emperor in a new way and helps him grow or face new threats.
The 'Redemption' trope is often seen in 'Highschool DxD White Dragon Emperor OC Fanfiction'. Maybe the OC has a dark past that they are trying to atone for, and their relationship with the White Dragon Emperor helps in that journey. The 'Alliance' trope is also popular, with the OC forming an alliance with the White Dragon Emperor against a common enemy. This can lead to epic battles and strategic planning within the fanfiction. And don't forget the 'Discovery' trope, where the OC discovers something new about the White Dragon Emperor or vice versa, which can change the course of the story.
Akeno Himejima is also a favorite. Her dual - nature, being both sweet and having a darker, more sadistic side in battle, adds depth to her character. In fanfiction, she can have different interactions with the Red Dragon Emperor, from being a close ally to a potential love interest.
One interesting storyline could be the Red Dragon Emperor exploring new powers. For example, he might discover a hidden aspect of his Boosted Gear that allows him to access a different form or ability. This could lead to him having to train in new ways and face challenges that he wasn't prepared for before.
Another theme is identity. The OC has to figure out how being a Dragon Emperor fits into their new life in the Highschool DxD world. They might struggle with whether to embrace it fully or keep it a secret. For instance, they may worry about how their friends and foes will react to their true identity.
One of the most exciting aspects of Highschool DxD OC Dragon God fanfiction is the creation of unique characters. Writers can design their own original characters (OCs) with dragon god powers, which adds a whole new layer of intrigue to the story. For example, an OC dragon god could have the power to manipulate time, leading to some really cool plot twists.
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.
Often, the unique feature is the blend of the red dragon concept with the existing highschool dxd lore. For example, the red dragon might bring in new powers or abilities that the regular highschool dxd characters don't have.