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 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.
One popular BL Chinese novel is 'Grandmaster of Demonic Cultivation'. It has a richly developed world, complex characters, and an engaging plot that involves mystery, friendship, and of course, a touch of BL romance. The story follows Wei Wuxian, a talented cultivator who has a unique approach to the art of cultivation.
I think 'Sasaki and Miyano' is also among the best. The story is set in a school environment. Miyano is a fudanshi (a boy who likes BL) and Sasaki is a popular boy in school. Their relationship starts from Sasaki's interest in Miyano and slowly blossoms into a deeper connection. It has a lot of cute and heart - warming moments, and the way their relationship progresses feels very genuine. It also touches on the insecurities and self - acceptance that the characters go through.
Another is 'Yuri!!! on Ice'. Although it's more sports - centered, the relationship between Yuuri and Victor is really well - developed. It shows how they support each other, grow together, and their love story unfolds in a very natural and heart - warming way. The plot also has a lot of depth with Yuuri's journey to regain his confidence in skating.
Well, I am addicted. The beautiful art, diverse plotlines, and the exploration of emotions in BL manga make it hard for me to resist. Also, it offers a unique perspective on relationships that I find fascinating.