Responses
if you're pertaining to "this guy" who's the chairman of sayoung who killed jeongwon's mother, jeongwon isn't the chairman's son, his father is someone who his mother met from an orphanage during a mission. dakyung only initially thought that the chairman had a son from the highschool to take revenge for killing her boss, then it turned out that none of the two male characters were directly connected to the chairman. and learning that jeongwon is her boss's son, so jeongwon now is trying to cover the existence of dakyung and taewoong since they were involved with the organization that his mother managed.
Deakyun plan was to kill the son of this guy aka the blonde dude but what was the blonde dude plan? Just to find the girl his mother always adored or what?