No, it is not appropriate at all. Spreading untrue stories about someone's sex life is an invasion of privacy and can cause great harm to the person's reputation and mental well - being.
We can start by not believing or sharing such stories without proper evidence. If we see someone spreading them, we can educate them about the importance of privacy and the harm of false rumors.
I don't have enough information to say exactly who Tara Reade is in these stories. She could be an ordinary person with an interesting story, or she might be a public figure in a specific community.
One common theme is the struggle between good and evil. Since Tara is often portrayed as a good character in the Buffyverse and vampires are typically associated with evil, the fanfictions often explore how Tara deals with the vampire elements, whether it's fighting them or trying to understand them.
One popular Buffy Tara vampire Tara fanfiction is 'The Magic Between Them'. It delves deep into the relationship between Tara and the vampire elements in the Buffy universe. It has great character development and some really interesting plot twists.