Merle Dixon doesn’t do warm and fuzzy. The maniacal gun-slinging racist and nastier of two redneck brothers on AMC’s genre juggernaut, The Walking Dead , Merle achieved cult status last season after sawing off his hand to escape encroaching zombies. Considering his few scenes, the level of demand for Merle’s return surprised both the network and producers, and might not have happened were it not for the humanizing force of actor Michael Rooker .

Rooker’s recent presence on the show, in the form of a hallucination, was not only Merle Dixon’s long-awaited reentry, but a stellar example of a network tapping into its characters–and their fans–to promote a series about the undead in a fresh way: Throw out just enough meat to appease appetites, but keep ’em hungry. And Rooker, who playfully dodges questions about his next appearance, dove into the scene with humor-laced swagger and improvisation. Coercing his semi-conscious younger brother, Daryl (Norman Reedus) into climbing a steep ravine to safety, not even Rooker knew everything that would spill out of his mouth.

“When I make things my own, that’s when the script comes alive, and that’s part of what makes Merle so memorable,” Rooker says. “I love the uncertainty of doing it as real as I possibly can. I don’t think about how I’m going to play a role. I’m more concerned with what’s underneath and between the words, who the person is, why he’s doing what he’s doing, and if what he’s saying is truthful. And then I let it roll. I equate it to being a jazz musician, who bends, twists, and elongates musical notes so they evolve into something more personal, when you’re pouring your soul into it.”

After nearly three decades in films like Henry: Portrait of a Serial Killer, Cliffhanger, JFK, Days of Thunder, and Slither, Rooker watched his popularity explode after a handful of scenes and a disappearing act last season, prompting three fan groups, a videogame gig in Activision’s Call of the Dead, and an AMC promotional campaign that teased his eventual Nov. 13 return.

From Merle’s ferocious anger in last season’s rooftop fight with the other survivors to the charged irony of his waving a pistol while demanding a democratic vote for himself as group leader, Rooker took pains to avoid affecting a good ol’ boy cliché. But when Merle opened the next episode with a delirious, grasping, four-minute monologue that preceded his hand severing, his dynamic changed. “Merle had been a brash, crazy, loose cannon in the fight,” says Rooker. “This showed you a completely opposite side, and created more questions than answers.”

“What Michael does is literally command the screen in such a way that you can’t look away,” says executive producer Gale Anne Hurd. “He’s completely believable. When he was firing his gun during takes, unsuspecting people in Atlanta were hitting the pavement. I don’t know that another actor would have been quite as convincing. I’m sure, when he encountered people after the show aired, they probably assumed he was crazy, when he’s really a pussycat.”