Perhaps the power of Rai in this fanfiction is connected to an ancient prophecy. The vampire OC is the chosen one to fulfill this prophecy. They have to face many challenges and enemies who are also interested in the power. Along the way, they might fall in love with a human or another supernatural being, which adds a romantic sub - plot to the story.
The plot might involve the vampire OC discovering the power of Rai gradually. At first, they don't understand it, but as they explore, they learn how to harness it. They could use it to protect their human friends or to gain a higher status among vampires. For example, they might use it to defeat a powerful vampire elder who is causing trouble in their territory.
If there are humans in the story, they would probably be both afraid and fascinated by the vampire OC. The OC might have to hide their power at first to not scare the humans away. But as they get closer, the humans could become allies and help the OC in different ways. For example, a human hacker could help the OC find information about the origin of the Rai power. Also, other supernatural characters like werewolves might see the vampire OC as a threat and constantly be in conflict with them, while some might want to form an alliance for mutual benefit.
The plot could involve the vampire OC using Alucard's power to fight against other supernatural beings. Maybe there's a power struggle in the vampire world and the OC has to prove themselves.
One possible plot could be that an underdog OC (original character) from a small, unknown universe enters the Tournament of Power. This OC has a unique power that is not immediately obvious. As the tournament progresses, they start forming alliances with other unlikely characters. Through a series of battles and challenges, they gradually unlock the full potential of their power and become a real threat to the more established and powerful fighters. In the end, they might even make it to the final rounds, surprising everyone.
The plot could involve the vampire OC trying to find a place among the different vampire clans in Skyrim. He might face challenges from the Dawnguard, a group dedicated to hunting vampires. He could also form unexpected alliances with other outcasts in Skyrim, like some of the werewolves who also face discrimination. His vampire abilities like enhanced strength and speed would play a big role in his adventures, whether it's in combat or in sneaking around ancient ruins.
Maybe the OC has a special ability related to technology. Tyler is initially skeptical but soon realizes how valuable it can be. Their relationship grows as they work on upgrading the Power Rangers' equipment. Along the way, they also have to deal with a traitor within the team who is jealous of the OC's closeness to Tyler.
Well, it could be about the OC joining the Power Rangers team led by Levi Weston. They might start as strangers, then gradually build a friendship as they face various threats together. Maybe the OC has a special power that complements the team, and Levi Weston helps the OC to master it.
One possible plot could be that the OC is a new student at Cross Academy. She has a unique ability that Kaname is intrigued by, like she can sense vampires from a distance. As they interact more, Kaname starts to develop feelings for her. But there are also other vampires who see the OC as a threat to their existence and try to harm her. Kaname then has to protect her while also dealing with his own complex vampire society issues.
One possible plot could be that the OC is a new student at Cross Academy. Rido senses something special about her. He starts to follow her secretly, intrigued by her unique aura. As the story progresses, the OC discovers Rido's true nature but instead of being afraid, she is drawn to him in a strange way. Their relationship develops as they face various challenges together, like the conflicts between vampires and humans at the academy.
One possible plot could be that the OC is a new ranger from a different dimension. Jayden meets her during a battle against a powerful new enemy. At first, they have some misunderstandings due to their different fighting styles and backgrounds. But as they fight side by side more often, they start to understand and respect each other. Eventually, they develop feelings for one another while protecting the world from the growing evil forces.
An interesting plot could involve the OC slime being a sentient experiment from another dimension. In the Rosario Vampire world, it starts to develop emotions and a sense of self. It could be drawn to Moka because of her unique vampire - human hybrid nature. As it gets closer to the group, it has to learn about their world's rules and values. It might even accidentally create chaos by using its slime - based powers in unexpected ways, like accidentally covering the entire school in slime during a fight, which then leads to some comical and also some more serious situations as they try to clean it up and deal with the consequences.