a big tsundere. Ch3-4 we will see he actually cares about her (a little too much even). Also, ch5 we see him being in contact with the CP, so they probably worked together on some 'issues'? So my guess is, dad tried to protect her and pull her away from drama by leading her to that shadow room, and the CP was supposed to get her out/save her, and that dagger probably had some symbolic meaning, if not some kind of magic protection or whatever... But, her dad being like that, and constantly being denied love by everyone made her do the deed. In ch4 she gets sick (I guess fever or smthn) and dad goes manic desperate, he holds her hand while she's unconscious and calls out (I can't read Korean, so I suppose it was along the lines of 'please don't die' etc.) which leads me to believe in the original timeline, after she kills herself, her dad becomes devastated, I wouldn't be surprised if he looked for ways to bring her back or stuff like that...