After a year, I decided to rewatch it. The foreshadowing from the ost on the first eps is insane. Also I am now 100% sure that ZWS is alive because of all the little details of hints that I miss first time I watched it.
Okay my prediction why Dr Roy likes being with Dr. Cha. I believe both know each other long ago. Dr. Roy is from an orphanage maybe Dr. Cha went there for something like a volunteer when she was young and meet Dr. Roy there. Maybe Dr. Roy knows her long ago and Dr. Cha seems to brighten his life a bit in the orphanage thats why he cares so mucb for her.
The fl acting is very off too.
PS. Im on Episode 8 so dont spoil me