 References to the character's abuse of prescription drugs are believed to be an allusion to Rush Limbaugh's addiction to painkillers.The nightly in-character guest interviews were initially of concern to Colbert, who worried his character's belligerent nature would be off-putting to guests.However, since the show's debut, he says he has found he is able to "slide the intensity" of his behavior depending on his interviewee's ability to respond to his aggressive approach.