Mental Retardation

Karl is mentally retarded. Karl is slow and does not always process the things around him the way other people do. Thus, Karl retains a sort of innocence. Although he knows that murdering people is wrong, he has a feeling that he has no choice when it is to protect those he loves.

Using Karl's disability as a storytelling function helps viewers to understand the themes in the film. If Karl was what we might call "normal," he might seem cruel and inhumane when he kills his mother, her lover, and later, Doyle. But, since he is mentally retarded, his actions somehow seem justified, and the viewer relates to Karl.

We are also able to see other people's motives for what they are. For example, we see Doyle's prejudices even more powerfully because of the way he treats Karl. Doyle hates anyone who is different, even when...