Doc Dans personality is very boring and annoying

Noooo not my baby

His character is being poor and miserable. That happens when you want to add a toxic second lead to the story, so you need a highly submissive and sorry main lead to keep up with him. Otherwise he would not stay.

I really hope both of them get therapy, Dan to build even a passable level of self-confidence, and Jaekyung for traits that are more than obvious.