“As the series was coming together,” Costabile says, “[Koppelman and Levien] were reinventing an entire character, someone who was essential to the whole story.” Perhaps the single most recognizable symbol of that process was Costabile’s own contribution: Wags’s signature mustache.

“We originally said to him, ‘Maybe you shave your head,’” Koppelman recalls. “And he was like, ‘I will if you want, but let me show you another idea.’”

“I really pushed Brian and David to have the twisty mustache,” Costabile says. “I was like, ‘This should be who this person is. He knows what he’s doing. He knows that on some level, if you looked at him, you’d be like, Who is this guy with the twisty mustache? The guy who’s either pretending to be the devil or is the devil? What the fuck is going on? It seemed like such a fun chess move. He’s not somebody who pushes you off balance, he pulls you off balance, pulling you in in order for you to fall.”

“He showed up having organized that mustache,” Koppelman says, “with the wax and the upturn thing, and I remember we were just like, ‘Yep, that’s the guy. That’s Wags.’”

I spoke with the creators, cast, and actor David Costabile himself about the creation of Wags, Billions‘ best character, for Vulture. This piece was a long time in the making and I hope you enjoy it!