Why the author always try to make Hye sung the bad one
I actually get what you meant. It's not very obvious and clear but it is implied. Like how they wouldn't do anything because Hyesung avoiding to talk about his trauma and past was pictured as "we don't want to give him hard time", like we afraid of his reaction and response rather than it is just bad. Whether or not his reaction is positive, they have no rights to decide it for him.
Everyone should read the parent side story, Ashley and Koi. They may not a perfect parent, but they did their best. In latest Ashley and Koi side story shows that Ashley do cares about his kids but don't know if the methods was correct or not. I mean he's also don't have good example to follow given how he was raised.
what about with chase?