This is just a theory of mine, but I think that maybe the guy that got raped in the video wasn't Han Siwon after all but his twin brother Jiwook! And after that, Jiwook dyed his hair and sort of 'escaped' Joohoon. That doesn't explain why the original Han Siwon commited suicide but it would be quite a twist.
That could be true since Siwon and Jiwook look so alike. Jiwook's expression after listening Joohoon's name kind of show that he is traumatized. But, it might also be that Joohoon was searching for Jiwook but couldn't find him and then end up letting out his anger towards the innocent brother. Or something else. The author's thoughts is so out of the box... And yours too are also out of the box to think of such a great theory I might overlook.
I thought they would make out. But it's okay. It will get even more exciting in the future.
I knew it. Joohoon clearly have some direct relations to Jiwook. Friendship? Hell no. Relationship? Might be so. I think they had affairs...