Well, you could make your fallen angel OC a bit of an outcast even among other fallen angels. Maybe they have a different view on the war between angels and devils. For example, they could be trying to broker peace in secret. They might also have a special connection to a certain sacred object that was lost during their fall, and the story could revolve around finding it again. Also, giving them a distinct personality trait like being overly curious about human culture could lead to some fun and unique storylines.
A great idea for a Highschool DxD Fallen Angel OC Fanfic could be an OC who was once a very powerful and respected angel but fell because they were framed for a crime they didn't commit. This fallen angel OC could then be on a quest to clear their name while also trying to survive in the new and often dangerous world of fallen angels. They could encounter the main characters from Highschool DxD and form alliances or rivalries with them. Along the way, they might discover secrets about the true nature of their fall and the politics that led to it, which would make for a very engaging fanfic.
A good plot for Highschool DxD fallen angel OC fanfiction could start with the OC being hunted by a group of vengeful angels. As they run, they end up in the territory of the devils and have to make a deal with them to survive. Along the way, they fall in love with a devil, which creates a whole new set of problems as their two worlds collide. Or, the OC could be trying to solve a mystery that dates back to the very beginning of their fall, something that involves a prophecy that only they can fulfill.
One common theme is the struggle of the OC fallen angel between good and evil. They often have to decide whether to follow their darker fallen angel nature or strive for redemption. Another theme can be their relationships with the other characters in the Highschool DxD universe, like forming alliances or rivalries with devils, angels, and other supernatural beings.
One interesting plotline could be Issei's struggle to control his new fallen angel powers while still maintaining his relationships with his friends at school. For example, he might accidentally use his powers in public and have to cover it up.
To develop a great Highschool DxD Fallen Angel OC, start with their powers. You can base it on traditional fallen angel powers but add a twist. For example, if they can use dark energy, maybe they can also transform it into something useful like a shield. Next, think about their relationships. Who were their friends as an angel? Are they still in contact with any of them? How do they interact with other fallen angels, devils, and humans? And don't forget their goals. Do they want to regain their angelic status? Or are they content with their new life? All these elements combined will create a well - rounded character.
To create a compelling fallen angel OC in Highschool DxD fanfiction, first focus on their backstory. Maybe they were once a high - ranking angel who fell due to a disagreement with the celestial hierarchy. Give them unique powers, like the ability to manipulate shadows in a way that's different from other fallen angels in the series. Their personality should be complex, perhaps having a sense of regret for their fall but also a new - found freedom. For example, they could be cynical towards the angels they once served, but still hold some of the old values deep down.
One idea could be a female OC who is a transfer student with a unique Sacred Gear that no one has seen before. This could lead to all kinds of adventures as the characters in the Highschool DxD world try to figure out what it is and how powerful it could be.
One idea could be that the loli OC is a new transfer student at Kuoh Academy. She has a special power that she's unaware of at first, like the ability to communicate with mythical creatures. As the story progresses, she gets involved with the main characters from 'Highschool DxD' and they help her discover and control her power.
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.
One common plot idea is an angel falling in love with a devil, which goes against the norms of their respective worlds. It creates a lot of drama and tension as they try to navigate their relationship while also dealing with the expectations of their own kind.