In The Road, the father and son are cut off from their home, civilization, and experience a feeling of exile because of it. Their exile proves both alienating and enriching, two essential elements of literary exile.
Alienation is the state of being isolated, or viewing the world from an objective standpoint. The father and son are forced to alienate themselves from the world because of its innate evil. As the boy grows older with this point of view, he comes to know the world as predominantly evil. The isolation of the father and son from the rest of the world because of their being good guys and the overt maliciousness of everyone else they come into contact with enforces this view point. The fathers alienation is different. He becomes consumed with the boys survival and well-being, not his own. This causes him to make decisions that the boy views as wrong in order to survive.
Exile can also be enriching. Sophocles showed this in his Oedipus trilogy. Oedipus exile forced him to examine his life and therefore move past his mistakes and hope for the future. The father and sons experience is much the same. Their world is filled with omnipresent evil. But they remain. Through the fathers teachings and the boys experiences, they retain hope. The boy feels like he is carrying on the legacy of the good guys. This compels him to retain his moral center even when the father does not. Whenever the father and son come into contact with evil, the boy pleads with his father for mercy.
The father and sons experience with exile is essentially a synopsis of the theme of the book. Their journey through the living hell of the world is harrowing; filled with narrow escapes and brushes with the pervading evil. Throughout it all though they retain their hope, the only thing they have. They come to know that although evil may seem indefatigable, good will always survive, as they have.