I have polarised opinions about this. I loved the theme but I think it couldn't have been executed better. I did find certain aspects of it to be cringe, and self-serving at times as well. And I don't think they showed his struggle with atonement well. But overall it was a good read. (⌒▽⌒)
I knew that the brothers' intentions were incestuous from the get-go. His concept of "protectiveness" was way beyond plain obsession. Something irked me then and there . (⊙…⊙ )
I'm kind of sceptical about the people who want the own Siyoon back. His craziness was definitely needed for the plot but for him to taste his own medicine, he has to be sane for a while. His actions have made her like this and he needs to take that in. If you like the obsessive Siyoon that much, I'm sorry but you need therapy (⊙…⊙ )