I admire the drama on some level for having characterization so strong that I can feel all of this is just a replay of previous events even though there's no direct reason for me to do so. For the most part these people are all stuck in a cycle they can't really break out of, because there's never been any compelling reason to. They're all basically happy enough doing what they're doing that they don't want to rock the boat. At this point I'm pretty sure Jae-Kyoung has killed before too- the guy just knows what he's doing too well.