I was really doubting about the possibility that the author might give us his backstory, but I'm glad she did. Wookyung appears to be a lonely neglected child, one of those children who grew up with people having high expectations of them but didn't even get the love of their parents. Growing up without an example of how love is supposed to look like and how you should treat a loved one, of course you’d have a distorted image of how things are. Since he doesn't know how to act he proceeds to ra** and lock his victim cause it's the only way he thinks it's gonna make Minho stay. He corners him in his house cause he's well aware that Minho doesn't share the same feelings and never will ( REMINDER: MINHO IS STRAIGHT).
Other than that Wookyung is an extremely self reflecting character even if he doesn't seem at first glance: "But now to think he hates me, it makes me anxious"
"What do I do: force him to stay until there's only one of us left? Or be honest and wait for him to return my feelings?"
"Why am I scared?"
He's full of fear and anxiety, guilt and anger, obsession and love...he isn't able to manage and recognise all of these feelings he's experiencing all at once: "Why? Why am I scared? What does scared even mean?"