Gary Poulter was a charming movie star with shockingly pale blue eyes and smooth dance moves. He was a smart kid from California who dreamed of joining the circus. He was a Navy man and a drunk. He was a homeless drifter missing most of his teeth and part of one ear. Gary Poulter was kind. Gary Poulter was vicious. Perhaps Gary Poulter was just a little like you and me.

Art Imitates Life

Casting agents John Williams and Karmen Leech were hunting down a different strain of actor for David Gordon Green's Joe, a film adaptation of Larry Brown's Southern gothic novel of the same name about a volatile ex-con who befriends a teenager and tries to save the boy from an abusive, itinerant father and a mean world that evokes William Faulkner's depraved Snopes family. "David said, 'Go and find me characters,'" Williams said. They cast a wide net, walking the streets of Austin and driving almost to Beaumont with stops at every Walmart, roller rink, and youth correctional facility along the way. They approached their job like cops – always alert, instinctively hunting for just the right face, that one persona that pops.

At Sixth and Congress, the duo found themselves chatting up a homeless family. "Don't talk to them!" a nearby man screamed at the family. Over to the side, a blue-eyed man with a crazed tangle of thinning white hair commanded in his gravelly chainsaw voice for the man to shut up and leave everyone alone. Williams and Leech began to examine this fiftysomething man more closely. He had an open wound on his head. He looked like he'd been on a drunken bender.

"I'm an actor," Gary Poulter told them.

In truth, Poulter's acting career was as a background extra on late Eighties TV series Thirtysomething. But he oozed charisma, and, oddly, he spoke fluent Japanese. They brought him in for a taped audition, and a grinning Poulter performed a pop-and-lock dance for the camera. They had Poulter in mind for a small part, but when Green saw the video, he sensed something bigger. Poulter was called back to audition for him in person and was offered the film's third lead: Wade, a drunken, abusive father who never settles in one place for long. In many ways, he was Poulter. "To me there's something about someone who's lived it," Williams said. "If they can act, it conveys on film. You can't fake cirrhosis of the liver."

But could a homeless drunk be trusted to come to work sober? Were there underlying mental health issues the film crew wasn't seeing? "We talked to his sister Maria [MacGuire], and she said he'd had his issues in the past, but this was his dream," Williams said. "If we could control him and keep tabs on him, she believed he could do it." Poulter and Green had a private conversation that sealed the deal. Then the new actor had lunch with film star Nicolas Cage at Annies on Congress, and the two bonded over a love of metal music. From the restaurant, Poulter called his sister. He handed the phone to Cage, who told her: "I just met your brother. He has the best sense of humor."

On the set, Poulter was known as Ozzie to avoid confusion with Tye Sheridan's character, Gary, the son of Poulter's Wade. Production coordinator Shanti Delsarte wanted Poulter to connect with the outside world, so she got him a laptop and set him up to talk with MacGuire on Skype. Delsarte was quickly charmed by Poulter, who came to the set even on days he wasn't filming and lent her his prized possession – a pair of roller skates. He restricted his drinking to beer and showed up to work sober. "He wasn't like, 'Thank you, you saved my life,'" she said. "He was humble and happy, but he was strong."

MacGuire, seven years his junior, hadn't seen Poulter in person for years before she flew to Texas from her Colorado home. Her brother had been hired by a traveling carnival, and the two reconnected over dinner. Back at home three days later, a desperate Poulter called. He'd been caught stealing money and had been left naked on the side of the road. She paid his way back to Austin, supplied him with a cell phone and paid for a motel room where he liked to show off his roller skating skills in the parking lot. A few weeks later he called with news of the film.

On Facebook, Poulter posted: "The production company moved me out of Motel 6 and decided to put me in Hampton suites...... TH