What are some interesting plot ideas for Highschool DxD OC Harem Fanfiction?

One idea could be an OC who is a transfer student with a unique power. The harem could form as different characters in the Highschool DxD world are intrigued by this power and gradually fall for the OC. For example, the OC might have the ability to heal wounds instantly, which is very useful in the battles that often occur in the DxD world.

The OC could be a new transfer student with a mysterious past. As the story progresses, it's revealed that they are on a quest to find a powerful artifact that is somehow connected to the characters in the harem. This could lead to adventures together, and the building of deeper relationships within the harem.

One idea could be the OC having a unique power that attracts the various characters in the harem. For example, if the OC can manipulate time in a certain way, it could lead to some really interesting situations. Maybe they use this power to save a member of the harem from a dangerous situation, which then makes that character develop strong feelings for the OC. Another plot idea is the OC being from a different dimension and having to adapt to the Highschool DxD world while building relationships with the harem members.

One idea could be that the OC has a unique power that helps Rias and her harem in unexpected ways. For example, the OC might be able to sense danger before it arrives, allowing them to better prepare for battles against other factions. Another plot could involve the OC having a past connection to one of the members of Rias' harem, which creates some drama and tension as they navigate their new relationships within the harem. Maybe the OC is a long - lost relative or an old friend who has changed a great deal.

One idea could be the main character, as the harem queen, having to deal with rivalries among the members of the harem. Maybe there's a new girl who challenges her position and she has to prove herself through various magical trials.

Perhaps a plot where the members of Vali's harem start developing new and unique powers. They then have to train together to control these powers while also facing threats from other factions in the Highschool DxD universe. This would involve a lot of character development and relationship building within the harem.

Maybe the story could revolve around the main character accidentally hypnotizing the wrong person in the harem, which leads to a series of comical and challenging situations. He has to then find a way to reverse the effects without causing too much chaos among the group.

One idea could be Gasper using his unique powers to protect his harem members from a new threat in the high school. Maybe a group of rogue devils tries to target the girls he cares about.

Well, a plot could revolve around the main character getting sent on a special mission by the school's authorities. Along the way, he meets new female characters who end up joining his harem. Also, there could be a plot where the harem members start developing their own unique powers and they have to train together with the main character. This could strengthen their bonds not only as a harem but also as a team. And then, there could be a mystery element where someone is secretly trying to break up the harem, and the main character has to find out who it is.

One idea could be an OC demigod who has the power of a forgotten god. They could use this power to help the main characters in unexpected ways, like having the ability to manipulate time on a small scale during battles. Another plot could involve the OC demigod trying to find their place in the world of Highschool DxD, being half - god and half - something else. They might struggle with acceptance from both the devil and angel factions.