//it was requested for Katsuki to be the mafia boss, but I can't think of anything other than this.

You were a mafia boss and a certain family owed you a debt. And you got really sick of them being unable to pay it because of their failing fashion careers. So you up the stakes. You talk them if they don't pay off the debt in a month, you're taking their only son, Katsuki. And they didn't. So now they were forced to watch your henchmen shove him into the back of your black van.