If, as Existentialists argue, existence precedes essence, then it is logical to assume that one can live and entire lifetime with out essence or meaning. Though this seems to be the case with the two pairs of characters, Vladimir and Estragon and Lucky and Pozzo, in Samuel Beckett's Existentialist masterpiece, Waiting for Godot, it is in fact quite the contrary.
Before understanding the essense of the characters in this play, it is imperative to understand the Existentialist definition of existence. Although variations of this definition exist, "existentialists generally suppose that existence as a human being entails both unqualified freedom to make of oneself whatever one wills and the awesome responsibility of employing that freedom appropriately, without being driven by anxiety toward escaping into the inauthenticity or self-deception of any conventional set of rules for behavior and sometimes with the aid of luck, even though the entire project may turn out to be absurd" (Philosophical Pages). With this definition in mind, the essence of the characters becomes very clear.
Vladimir and Estragon seem to be living excrutiatingly routine lives, void of all meaning and essense. However, their frequent conversations about seperating make it obvious that they know they can leave their relationship if they so wish and therefore are choosing to stay. With this decision, they have chosen routine, conversation, and waiting for Godot as their essense. While this may seem meaningless, they make the decision to continue this way with authenticity and therefore it follows the definition above. .
Pozzo and Lucky have also chosen their collective fate. To understand the deicsions these characrters make it is nessesery to first understand their relationship. Strictly speaking, Lucky is Pozzo's slave. Realisticly speaking, they are each other's slaves. Lucky does perform an endless number of menial tasks for Pozzo on command but by doing so he also ensures Pozzo's dependency on him for even the simplest of things.