It’s not that Jon Bernthal is a character actor, it’s just that you really, really, do not want to fuck with any character he’s ever played. Whether it’s the homicidally-realist Shane from The Walking Dead, the terrifyingly-uncouth “Coon-Ass” in Fury, or the skull-shirted vigilante the Punisher, Bernthal has a habit of playing People You Do Not Want To Mess With. Hell, he even managed to play the most badass high school history teacher on screen in Me and Earl and the Dying Girl.

On Monday night, Jon Bernthal told Jimmy Kimmel what he does to prepare for playing lunatics, killers, and stone-cold vigilantes — method acting.

“I kinda have to stay in character,” he said, “I know it sounds so pretentious! It’s a lot of isolation and sort of… not having too much fun.”

Bernthal’s performance as the Punisher has been widely praised, so it’s no surprise he went to great lengths to nail Frank Castle’s complicated, conflicting character.

“He [the Punisher] lives in a world of darkness, and so my job is to kinda embrace that,” he told Kimmel, who promptly made the risky decision of asking a man who just admitted to method acting as a revenge-crazed vigilante with a murdered family how his own family felt about the role.

Bernthal said re-creating the Punisher meant he had to partially isolate himself from his family throughout the time he was filming. “That’s a tough part of the job, I need to stay pretty separate,” he said, “It’s pretty much ongoing, I’m definitely not that much fun while I’m playing this part.”

His son Billy, he said, likes Daredevil more than the punisher — but don’t worry Jon, Inverse thought you were great.