The settings in BL vampire novels are usually quite dark and gothic. Think of old castles or shadowy cities. This setting helps to create an atmosphere that is both spooky and romantic for the BL relationship to unfold. For example, in many such novels, the vampire's lair becomes a place of both fear and a sort of strange intimacy for the lovers.
One common theme is the power imbalance. Since vampires are often depicted as more powerful than humans, in a BL context, this can create an interesting dynamic between the two male characters. Another theme is the struggle with identity. The vampire character may be struggling with his vampiric nature while also dealing with his feelings for the other male character.
Sure. 'Captive Prince' is a great one. It has elements of a vampire - like world and also has a strong BL relationship. The story is full of political intrigue and a deep emotional bond between the main characters.
It's not uncommon for such a twist in BL manga. The boy next door could totally be a vampire if the story is set up that way to add excitement and mystery.
The fanfiction probably also plays with the typical vampire tropes. For example, there could be a struggle with immortality, bloodlust, or the idea of a vampire's allure. Sonadow's story within this might involve them dealing with these vampiric traits, either one of them being a vampire or both being affected by the vampire - filled environment. This can create a lot of interesting plot twists and character development.
One common theme is forbidden love. Since vampires and werewolves are often portrayed as natural enemies, their relationship goes against the norms of their societies. For example, in many novels, they have to keep their love a secret from their clans.
One popular vampire BL novel is 'Captive Prince' which has elements of a vampire - like world and a complex relationship between the main characters. Another is 'Aristotle and Dante Discover the Secrets of the Universe' which has some dark and mysterious undertones that can be associated with vampires in a way, and of course, it has a beautiful BL relationship.
Love and passion are likely main themes. Vampires are often associated with intense emotions, and a kiss in this context could symbolize a deep connection.
Well, in many vampire novels, 'vampire's kiss novel' could potentially center around a vampire who forms a connection with a human. This connection might start with a kiss that has some sort of significance, like it could transfer power, or start a transformation in the human. There could also be a struggle between different vampire clans or against hunters, all while the main characters navigate their relationship.
I'm not sure if it's extremely popular. It might not be as well - known as some mainstream bestsellers. It could be that the vampire genre has so many books, and this one just hasn't gotten as much mass - market attention.