
I think the reason it is Kihoon bearing the consequences when Yeon was the one to tie that string is that, in the past life, when Yeon was dying (we see him struck by arrows), Kihoon must have made a bargain/deal/whatever with the red string boulder to take the consequences on himself. And thats why HE has the misfortune in this life, not Yeon.
im sold. lets gooooo