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.
Spicy BL manga is known for its steamy and intense depictions of male-male romance. The character development is centered around their passionate connection, and the settings and conflicts add to the allure. However, it's important to note that the level of spiciness can vary depending on the specific manga and the author's style.
Well, 'Love Stage!!' could be what you're looking for. It has similar elements of a blossoming romance and character growth like in Chansoo. The art style is also appealing and the story keeps you engaged.
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.