Brad Renfro stars alongside McKellen as Todd Bowden, a 16-year-old who discovers Denker's criminal past. Singer auditioned a couple hundred young men and chose 14-year-old Renfro, saying of him, "Brad was the brightest, the most intense and the most real. Not only could he have the intensity when we wanted, there was a hollowness that he could convey, and by the end of the picture he had to become this empty vessel." Portraying a manipulative character temporarily influenced Renfro, who said that people around him were worried about his state of mind. Renfro said of his performance, "It's a trip I have to take. People just kind of have to leave me alone when I'm doing it. It's my job." Singer described his impression of the character: