Alright so this is just a theory.
Since Guwon had already seen him switch personas, what if the smegs was a test to see if he loses control? Y'know to see what potential he has. (The part where he puked, i think is a give away) But instead it backfired on him and he eventually loses control that's why in the first season, it was Guwon holding teach, now its teach holding Guwon.
Also probably part of the reason he took him in is because they're both an enigma? Guwon sees him as some puzzle he can unravel, bcs apparently Teach has another persona and Guwon doesn't know much abt his past (ik he's seemingly dumb but I knew better than to trust povs from manhwas) and that made him want to observe him. And along the way, probably another turning point was when Teach stood his ground against oppressors. And that pulls him in even more to him because teach has a moral compass he doesn't understand, which in turn makes him more obsessed with him.
Which again, probably shows why it's Guwon looking at Teach and Teach looking at us with a gun because he will use Guwon's dependence as a way to change things.
The gun being behind the back is probably a give away that he will do things behind Guwon's back, while he's distracted with his affection towards him. AND his eyes turning away probably means that he's not as naive as he was, he's holding him but he's not emotionally involved as he was before.
i could be wrong, but i think op means guwon puked because he had no substance to sustain any true sexual attraction to the teacher yet, it was more like pet v owner type of dynamic, he viewed the teacher as a being who he can take care of, not necessarily love. that’s why, he kissed him and wasn’t really into it—it was more like appeasing a dog that licks your face when you know it can be rabid, you just don’t know when.
the potential might refer to the teachers hidden “side” that i believe is aggressive, cut-throat, and deadly, like his instincts that made him almost stab guwon that one time. there’s repressed trauma and i hypothesize he killed his father.


Ya gonna die brch keep going with that attitude