Responses
Chi-Hwan became human because Sooin’s blood was “poison” and turned him last second, while Sooin, on the verge of dying, turned into a vampire with Sungha’s (and also Chi-Hwan’s?) blood. I guess that broke the contract Chi-Hwan had with Choi Joohyun and made it possible for Sooin to form a new blood contract with Chi-Hwan. The vampire can die from getting its heart ripped out, but the human is completely immortal as long as the vampire is alive. TLDR: if the vampire dies they both die but if the human dies the vampire still lives.
I just spoiled myself, but is the link like makes the other(human) live forever too? Like their lives gets linked together and if either one of them dies, the other dies too?