Well that's dark

Spoiler











So, MH kills NH and is emotionally abusing YJ. I'm guessing it's going to go one of two ways:
1) YJ starts to get closer to the director and they start sort of dating. MH goes batshit and crosses a line with YJ that pushes him further awayand kind of forces HW to take him not (not that he's going to mind), and we're gonna see that HW is a serial killer murdering people and MH comes to save YJ and HW will just out MH as NH's murderer.
Or 2) same basic set up but HW actually turns out to be a good guy and while being sidelined by YJ even though they're interested in one another. MH puts pressure emotionally and physically on YJ but YJ just can't leave him. That's when MH will try to kill HW. He's done it before so why not and he's been doing it this whole time with strangers (maybe people who resemble NH??), so offing HW will be a breeze. But YJ is stuck on HW, having found out MH killed NH and then left after a big blow up. He'll probably kidnap them both (warehouse scene!) and tie up YJ until he says he loves MH and will be with him. But will go to kill HW anyway, because he knows YJ is lying. YJ will jump in front, save HW and HW will either be let go by MH to get YJ medical treatment and MH will disappear and YJ will slip into a coma, or MH will turn himself in and accept punishment for his crimes and YJ will do the whole "I'll wait for you" bs because he's so manipulated by MH.
It could be a mix of the two scenarios but I would be sure it's not one of those two.