Well, perhaps the plot could involve Hermione being bitten by a vampire during one of her adventures. Then she has to deal with her newfound vampiric nature while still trying to maintain her relationships with Harry and Ron. She might struggle with her thirst for blood and her moral code as a witch.
It could be an old and powerful vampire who sees Hermione as a threat to his rule. Since Hermione is a very intelligent witch - now vampire - she might be able to figure out a way to undermine his power.
One possible scenario could be that Finn, after being turned into a vampire, struggles with his new identity. He might have to deal with the urge to drink blood while still holding onto his old values. For example, he could try to find alternative ways to satisfy his thirst that don't involve harming humans, like drinking animal blood.
One idea could be that Stiles is turned into a vampire against his will. Maybe he's attacked one night while out investigating something supernatural. As a vampire, he has to struggle with his new urges, like the thirst for blood, while still trying to be the same person his friends know. He might start to see the world in a different light, both literally and metaphorically, as his vampire senses heighten.
One possible story could be that Mimiko is bitten by a mysterious vampire one night while walking alone. She then starts to experience strange cravings and enhanced senses. At first, she's terrified, but as time goes on, she begins to embrace her new vampiric nature.
One popular one is 'A Dark Bond'. It delves into the complex relationship between Severus and Hermione in a vampire - themed world. The story is filled with mystery and tension as they navigate their new, dangerous situation together.
One possible scenario in this fanfiction could be that Finn's transformation into a vampire brings out a whole new side of his personality. He might struggle with his newfound thirst for blood while still trying to uphold his heroic values. Maybe he teams up with Marceline, who is already a vampire, and she teaches him how to control his urges.
One great Hermione - as - a - vampire fanfiction is 'Bleeding Hearts' where Hermione's transformation into a vampire brings a whole new set of challenges and adventures. The story delves deep into her struggle to control her new instincts while still maintaining her friendship with Harry and Ron.
Another idea could be that she is somehow brainwashed. There could be a dark spell or a powerful magical object that alters her perception and makes her believe in the Death Eater ideology. In this scenario, her friends would have to find a way to break the spell and bring her back to her true self.
One possibility in this fanfiction could be that Hermione is forced to become a Death Eater due to a powerful dark magic spell that controls her mind. This would lead to a great internal struggle as her original values clash with the cruel and dark ways of the Death Eaters.