to be fair, when someone faces something traumatic/tragic - perhaps something similar to what Su Yeon experienced, the person often shifts all the blame on one person, because the hate to that person keeps them going in life... it's sad, but true
very good first episode, and yes, KYD will be a lot on there most likely, he's clearly a big character, as he's shown in the intro, right after the leads, not to mention I never understood people saying they watch drama just for one actor...