The final images we see at the end of the first season of Dexter are of Dexter Morgan receiving a hero’s welcome after killing his long-lost brother Brian Moser, aka Rudy Cooper, aka the Ice Truck Killer. Although the scene is heavy with the kind of self-conscious irony that has become one of the hallmarks of the series, it is also a reflection of the show’s success. One of the most remarkable things about Dexter is the way it has solved spectacularly well the puzzle that has baffled the vast majority of serial killer related popular culture that has come before it: how to have the audience identify with serial killers in a relatively unconflicted way. Finding the answer to this problem has enabled Dexter to become not only a successful television show and marketing and merchandising bonanza, but also a cultural phenomenon in its own right.

How has Dexter done it? The answer, in short, is through disavowal. 

The most successful forms of serial killer related popular culture give audiences a way to disavow their involvement and identification with serial killer characters. Dexter uses various techniques in order to achieve this outcome, including justifying the violence committed by its protagonist as moral acts of justified vigilantism, and by emphasizing the ethical system (the “code of Harry”) that dictates not only who Dexter kills, but also who he refuses to kill.

By far the most important reason for the success of Dexter however, is the series’ use of an “evil other” as a way to disavow the violent acts committed by Dexter. This figure is such an important part of the show’s formula that we can find an example of the type in each season: Lila Tournay, Miguel Prado, the Trinity Killer, and, of course, the Ice Truck Killer. In a technique borrowed from Thomas Harris's The Silence of the Lambs, Dexter creates audience sympathy for the “good” serial killer by contrasting him with a “bad” serial killer. Just as Buffalo Bill allows readers to maintain their attachment to Hannibal Lecter in a relatively untroubled form, so the Ice Truck Killer, despite his family resemblance to Dexter, enables us to continue rooting for the “hero” of the series. In contrast to Dexter’s murders, the Ice Truck Killer’s homicidal activities are malevolent, vicious, and unjustified. In short, he is everything that Dexter is not. As such, Brian has to die, and Dexter's killing of him, precisely because it is the most difficult thing he has ever done, succeeds in making the audience feel an unparalleled degree of sympathy with him.