@CasFujo white haired/ Baek Jun is the original vocalist of Dream Boy, Jaeyoung's boy band, who suddenly quit and Jaeyoung became the vocalist. He's also the one that fed Jaeyoung the drug Happy/H-100.
The guy picking him up from the airport is his uncle and he works for DIVE which is Dream Boy and Jaeyoung's management company. He was trying to sell the drug Happy in Seungmin's (rapper Happy) friend's club called Favela.
I think he might have also tried to expose the redhead from the band and Jaeyoung to the drug at the beginning, since there was a manager asking Jaeyoung to pick up the redhead from Favela because he was drunk and the manager was busy with another group. That's when the Happys met lol