An OC could be a witch with unique powers that gets involved in the political intrigue among the different vampire clans. She might have the ability to control the elements and uses this to her advantage. This could add a new layer of complexity to the relationships between the existing characters.
One idea could be an OC who is a powerful vampire hunter sent to the island where the story takes place. They initially clash with the main characters but end up teaming up to face a greater threat. For example, a new type of ancient vampire that is immune to the usual methods of slaying.
Maybe an OC who is a half - vampire, half - human. Struggling with their identity, they seek the help of the main character. They bring with them a secret about a hidden vampire society that has been operating in the shadows, which could lead to a whole new adventure in the 'Strike the Blood' universe.
A great plot for Strike the Blood fanfiction could be a time - travel scenario. Kojou is sent back in time to a period when vampires were first emerging. He has to use his modern - day knowledge and powers to survive in this ancient and dangerous time, while also trying to find a way back to his own time. This would allow for a lot of world - building and exploration of the vampire lore in the series.
Another plot could focus on the origin stories of some of the side characters. For instance, the backstory of Yukina Himeragi. How did she become an attack mage? What kind of training did she go through? A fanfic could expand on this and also show how her past experiences influence her actions and relationships in the present story.
A great plot idea would be a tournament where characters from both Naruto and Strike the Blood participate. Naruto's friends like Sasuke and Sakura could also be brought into this new world. They would have to learn the rules of the Strike the Blood world quickly and use their ninja skills to compete. The vampires in Strike the Blood might be intrigued by the ninja powers and try to learn from them. This could lead to some interesting alliances and rivalries.
A third plot idea is a character - swap scenario. What if Kojou Akatsuki wakes up in the Naruto world with his vampire powers? He would have to navigate the world of ninjas, clans, and hidden villages. Meanwhile, Naruto could end up in the Strike the Blood world, having to deal with the complex politics between the different vampire factions while also trying to find a way back home.
One idea could be that they get separated due to a powerful enemy's scheme. Kojou tries desperately to find Yukina while she, on the other hand, is fighting her own battles to get back to him. Their love for each other gives them the strength to persevere through all the hardships.
A cool plot could be that the OC is a witch with a mysterious past. She meets Alcide and initially they are at odds because of the werewolves' and witches' long - standing differences. However, they soon realize they have a common enemy. They have to work together to defeat this foe and in the process, they fall in love. It could involve lots of magic and werewolf lore.
Another plot could be that the OC is an ancient being like Godric, but from a different part of the world. They meet in a chance encounter and discover that they have a shared past that dates back centuries. This revelation could set off a chain of events that affects the entire vampire community in the True Blood universe.
One idea could be exploring the backstories of the individual witches more in - depth. For example, how they first discovered their powers and what their lives were like before joining the fight. Another could be a story about a special mission that the witches have to undertake behind enemy lines, filled with danger and unexpected alliances.
One idea could be that the Spartans from Halo and the Witches from Strike Witches team up to fight a common alien threat that has invaded both of their universes. The Spartans' advanced weaponry and combat skills combined with the Witches' magical abilities would make for an epic battle.
A great idea for Cormoran Strike fanfiction is to create a 'what if' scenario. For example, what if Strike never became a detective? How would his life have turned out? You could also focus on his family relationships more deeply. Write about his interactions with his half - brother, or how his mother's past influenced his own choices. And don't forget about the romantic aspect. A fanfiction about Strike and Robin's relationship developing in a more comical or tense way than in the original books could be really engaging.