Just my theory, Jin is fooling himself. Just like charin said, he's so fucking smart he actually fooled himself. Now what happens when he stops joking around and actually locks in like the Jin who fell from that aircraft? The Jin who was able to fight for himself, the Jin whom charin was jealous of because he's so goddamned genius he had him under his wings to feel better!? You remember how Jin invented things but charin destroyed it all and Jin just accepted bc he like charin? Yes yes. Or Or Or! He's not fooling himself? He's fooling everyone including us. He's just pretending, like a wolf in a sheep' skin. And once he stops pretending, he locks in.
It's just my theory tho, I could be completely wrong
Tehir ain't even do anything to Jin for him to literally fuck his body up. Like yeah Jin,Tehir's a narcissistic hypocrite but still
Btw those that are saying Jin is super genius or something,it's confirmed that Jin has low IQ alongside Garon and Ael.