Throughout Waiting for Godot Beckett utilizes pairing or doubling of characters. All the characters in the play are paired. Indeed, the main characters Vladimir and Estragon seem like twins. Pozzo and Lucky are so closely paired that they are connected with a rope. In addition, the pair of boys who come at the end of each act to announce that Godot will yet again fail to show up are interchangeable brothers whom Vladimir cannot distinguish between.
One of Samuel Beckett's main concerns is the polarity of existence. In Waiting for Godot, we have such characteristic polarities as sight versus blindness, life–death, time present–time past, body–intellect, waiting–not waiting, ruler-ruled, going–not going, and dozens more. This concern is served by grouping his characters in pairs. Vladimir's positivity and maturity contrasts Estragon's negativity and emotion; Pozzo's high authority and confidence contrasts Lucky's low authority and inconfidence; the boy's good fortune is a foil to his brother's misfortune. This pairing also emphasizes his theme of human dependency. Moreover, the Pozzo-Lucky pair acts as a counterfoil to the Vladimir-Estragon pair. The three sets of foils (two characters that complement each other) in Waiting for Godot display how dualities within a person are necessary to form a complete being.
Characterization is the key in establishing the theme of Waiting for Godot. Vladimir and Estragon seem to have two modes of existence: together and by themselves. One critic observes, "As members of a cross-talk act, Vladimir and Estragon have complementary personalities". Estragon is "child-like" and carefree; whereas Vladimir is more grown up and usually the decision-maker. They consider the option of leaving each other but never actually part. Worse than waiting is waiting alone, and loneliness is a form of blindness and invisibility, not seeing or being seen. Through the pairing of Gogo and Didi the play emphasizes the fact that the minimal unit of the human is not the one, but the two, and though the picture is a bleak, unsettling, and painful meditation upon our shared loneliness in the absence of Godot, the fact that we share this loneliness, this eternal waiting, with our friend is what can possibly turn our cries into laughter and our ontological loneliness into love.
The relationship of Vladimir and Estragon is contrasted with that of Pozzo and Lucky, who represent the antithesis of friendship. Theirs is also a relationship of intertwinement and dependence, but one of master and slave, of servitude, inequality, and dominance. The ambivalence of Pozzo's and Lucky's relationship in Waiting For Godot resembles most human relationships. Irritated by one another, they still must function together. References to their relationship are generally couched in rope images. Their relationship, however, does not stagnate at this point. The very next day, when the two appear again, the rope between them is significantly shorter so that the now-blind Pozzo may find his way. In this new situation, it is less clear which character leads the other, or if either one is truly in control. Overall, the relationship of Pozzo and Lucky seems to be a necessary evil. They never seem to agree on much or even get along very well, but still seem to be two parts of a single person. However they bicker or condemn each other, they need each other to function correctly, and whenever their relationship is in danger, they cease to function normally.
All current Beckett scholars see these pairings as a dramatic embodiment of the two parts of the human condition: the body as part of the physical world, and the mind as part of the abstract or mental perception of the world. The most obvious example of this duality is in the details of Didi's attention to hats (mental) and Gogo's attention to boots and food (the body). When combined with the master-slave relationship of Pozzo and Lucky, we discern that the mind is, or thinks it is, the master and the body is the mind's slave. Through such paired characters, Beckett is considering Man's condition, both his "existence" and his inevitable cessation, all a mystery in that their "purpose" is inexpressible.