Cain wins because he has a supernatural role.
Yawhi wins because he has a dark past.
Either Jooin "cures" Yawhi (which is unrealistic) or Yawhi is basically going down a darker path. According to the raws he already told cain that he doesn't need to put his guard up for Jooin, because I guess he was going to set him free. BUT cain hurts his pride and in turn Yawhi makes "a move" on Jooin in front of him. Next thing you know both guys are death-glaring over the thought of one another, so maybe we should stan Cain x Yawhi-
Jk
....
The fact that Cain was about to reveal what he was hiding only for Jooin to change the subject.
That in itself feels like his secret really isn't that bad. But we were so close, darn it Jooin!