Jiwook is very flawed which might be a reason why people like him.
Hmmm. Let's see now... a jealous little brother who didn't care that his older sibling got gang raped, bullied, abused, and pushed to suicide. If my little brother started getting more attention, should I tell people to rape him and take videos to post around the internet? *facepalms* Ah yes! How could I be so blind? Jiwook's terrible,victim-complex behaviour is SOOOOOOO relatable! And I'll forgive him because a guy who finds happiness in his brother's underserved abuse is SO complex and SO fascinating!
...with an insane victim-complex. Not really easy to like this Jiwook's character. I guess people are only liking it for the "OMG HOT YAOIZ I SHIP IT" factor.