theory about the link *may contain spoilers? if its right?*

i think the link (choi joohyun) may have chosen to betray chi hwan and become a vampire but maybe chi hwan didnt want that so the link became a vampire through someone else and that was a huge betrayal for him. idk im saying this bc the link heals incredibly fast plus he was on the roof of a huge building watching them when they went to sooin’s old apartment, like how tf did he get there without vampire powers