In my opinion, it will be Yigon who will flip the script. He's afraid that the ML will leave him but what if in the end, Yigon decides to leave the ML when everything's settled with his brother? Not because he wants to but because he knows he has broken the contract of not falling for the ML and he doesn't want to inconvenience him anymore with his "unrequited love".
And the ML will go crazy trying to find him lol
Just raw predictions, I think the “Flip the Script” here is that Taekang will fall even harder, regret it, and start chasing after Yigon. I’m not sure who will take revenge on Yigon’s brother later. I thought maybe Taekang would be the one to take revenge after he has fallen deeply in love with Yigon and cannot accept the fact that Yigon was treated horribly by his brother. But in my opinion, it would be better if Yigon himself takes revenge on his brother. ╮(￣▽￣)╭
I'm at a loss as to figure out which "script" is supposed to be flipped.