Info from WIKI
Jayhun was a devout Christian, which other apartment residents found odd. However, despite what he believed in, Jayhun was very tolerant of other beliefs. Through Jayhun's faith, he was able to work up the courage to do things that would otherwise terrify him. He was also very kindhearted towards others, even towards Hyun Cha who is infected. He was implied to be attracted to Jisu, as she was the last person Jayhun thought of immediately before death.