i don't really have an answer for all three questuons but I figured i could say my two cents on the current conflict!
I mean, yeah, Heewon totally could have said the safe words instead; both the sub and the dom can use it if they feel like it. What happened though probably has to do more w/ the fact that Heewon wants Wookyung to ACTUALLY understand the difference between play and abuse, and the fact that Wookyung is not only willing to dismiss that difference, but he also actively encourages abusive and toxic behaviours in the name of "pleasure" - all this just sent Heewon off the rails.
He didn't use the safeword because he was trying to get his point across, and in that moment that was way more urgent in his mind than him feeling uncomfortable over hitting Wookyung.
Also, not to justify any of this, because i think this is very toxic behaviour on both ends, but we have seen clearly how pushy Wookyung gets w/ bdsm play; he's continuously pushing Heewon's boundaries and dismissing his feelings, belittling him, saying he's boring all bc Heewon doesn't like to get THAT violent. So it makes sense, i think, that Heewon was completely blinded by the rage that something that should be very clear - aka the difference in bdsm between play and abuse, between play and violence - is still THIS hazy and light-hearted for Wookyung.
This is an interestingly toxic dom and sub dynamic but I have like 3 questions:
1. I get that Heewon wanted Wookyung to understand what's ok and what goes over the line but if he was so uncomfortable couldn't he just say the safe word instead? I thought doms and subs could say it
2. What the heck did safe words do to Wookyung for him to prefer being in an ambulance (and I mean he got what he wished for ig) than actually saying anything?
3. Does Wookyung possibly have a mental issue where he's just like unaware of himself or something? Was this ever a thing?