About the flashback

Lol a lot of people don't realise chapter 45 and 46 were flashbacks. They aren't having sex in the current storyline, this was in the past before yeonhong became a moneylender. The time they had sex in the flashback was the first time they "met". Panther back then didn't know yeonhong at all, and yeonhong had never seen panthers face yet. So, no they didn't just have sex right now, that was in the past before everything.

The guy he calls pig was his old boss/debt collector, but currently yeonhong is his own boss and has his own business. Basically panther was a higher up in the business and the guy he owed money to made him sleep with panther for a favor. Yeonhong was furious so he decided he needed to pay back his debt and leave immediately. He asks taein to join him, so he hires him and they go to Seoul together. The flashback ends in the beginning of chapter 47 when yeonhong meets the police officer outside the office

At the current timeline panther almost definitely recognizes yeonhong but yeonhong doesnt recognize him back, cause he never knew panthers face before they met in the present. He only knows panther is probably more powerful than he thought at first. We just aren't clear on what panthers motive is or why he basically sent himself to work under yeonhong