@Leonhart93 Considering the secretary's response, I feel the sister isn't going to be a bitch per say but I am afraid that she blames the ML for her sisters death when they were children. I do hope I am wrong and the secretary is just keeping her away from the ML because he certainly seems to blame himself and it might just trigger a panic attack or something like that.
About cho-won (her sister) for those who are concerned that she's going to be her rival :
No. Cho-won doesn't like Seoha that way. She simply likes Secretary Ha. And she also considers Ji-eum a good friend in the coming episodes.
And she's also the secondary FL----! After Joo-won!