"He's really sort of the devil," says Fiennes, 47. "He's completely emotionally detached. He has no empathy. You find that in psychopaths."
"It's about power with Voldemort," he says. "It's an aphrodisiac for him. Power makes him feel alive."
"Daniel's very nice, but Harry Potter's a pain," says Fiennes, scowling and hissing.
"Jo Rowling has always said that the thing that separates Harry from Voldemort is that Harry is not afraid of death," Radcliffe says.
Radcliffe was consistently unsettled by Fiennes. "When Ralph's doing his Voldemort stuff, he just really freaks me out."
"Ralph is mesmerizing," Felton says. "He never did two takes the same. ... I had to keep reminding myself: 'Stay in character. Don't just sit there and watch his performance.' "
Even when the cameras stop, the aura of Voldemort remains.
"He dominates scenes in the film, and it's like that off the set as well," Felton says. "He's quite a charming guy. And when he opens his mouth, people listen. Let's put it this way: No one talks over him."