A love triangle.
The uke (Sooin) who had a abusive relationship with Sungha, his childhood friend (middle/highschool). Wishing to escaped from the hell, he met the seme (Chihwan) a vampire who own the restaurant where Sooin works with. Chihwan wanted to make Sooin his, decided to help him escaped to Sungha abusive relationship. That's when Joohyun (Chihwan's link) appeared, making Sungha a vampire. Joohyun and Sungha team up to create a plan where both of them will benefit. Here's the lesson in this webtoon. GREED AND DESIRE. Joohyun greed to have both power and loved for Chihwan, turns back on him where he lost little by little the one he loved. The more he find him, his just going to killed someone who is related or close with Chihwan. Same with Sungha, his in denial of having a feelings for Sooin. He used his authority/power to pinned down Sooin, to make him mine. He thinks, "even though I hurt you, deep inside you love me." and that proved him wrong, that every he hurt Sooin, made him loved less little by little.
Human are disgusting yet interesting living things.
Dine With a Vampire