So, it seems as though that his maternal grandfather is a controlling manipulative person. That he wants his grandson to take over the company and from what I am understanding is ticked off that his maternal grandmother gave him all of the inheritance, leaving nothing to his maternal grandfather. Ideally, he’s trying to break up the couple and is using dirty tactics and order to do so. Including, kidnapping, sexual assault, and threatening. However, the guy that he used in order to complete these task has a backlog of the proof of all of the request that the grandfather has made. So, Taesung is trying to find a way to get the proof to escape from his grandfather and use it as a way in order to keep him away from hurting Haebom. Unfortunately, he feels a lot of guilt for hurting him in physical, emotional, and mental ways to protect Haebom. Overall, it seems as though his grandfather is a homophobic mf.
Hope this helps.
I’m just confused at this point with the plot and just this whole season