
From what I understood, they were in that give n take relationship. Hyeon would kill his friends and yiseon would help him clear Dungeon,6-6. But Hyeon kinda noticed yiseon is powerful and kind, also he planned to kill himself after all his friends were killed by hyeon. You see, from Hyeon's point of view it's a waste of resources if yiseon just kills himself, so laid honey trap for yiseon. Kinda trying to manipulate him to live (obviously a good thing but the approach is wrong), it's like hanging an apple in front of the donkey and exploiting him without letting him eat. Yiseon kinda knows that it's all hyeon's honey trap for him so that he can use his power, but he still went along with him(i think it's because he really decided to kill himself after all his friends were done) but gradually he felt comfortable with hyeon but hyeon showed no sign of that emotional attachment or sympathy. This brings us to what happened in chapter 88 and surprise surprise, we get to see that Hyeon might also have feelings for yiseon....
Why is everyone mad at hyeon...
Jeez guys he just doesn't know how deal with feelings and takes it as manipulation. When it comes to yiseon, he really doesn't need him after these dungeons yet he was happy that yieon was finally his...