In act 1, Estragon tells Vladimir that he slept in a ditch the previous night. He also admits that "they" beat him, but the audience is not given the identities of his attackers. Beckett also doesn't reveal exactly why Estragon is beaten.
In fact, Vladimir (the one who questions Estragon) never inquires about the identities of Estragon's attackers in act 1. Vladimir is, however, seemingly preoccupied with the subject of beatings. When the boy approaches him and Estragon, Vladimir wants to know if Godot beats the boy.
For his part, the boy reveals that Godot never beats him. Godot does, however, beat the boy's brother.
Later, Vladimir sings a doggerel (or comic ballad) about a dog who is beaten to death for stealing a crust of bread. It is later revealed that Vladimir was singing while Estragon was being beaten: whether or not he was singing this song is not specified, but it is possible. After Vladimir finishes singing, Estragon enters. Vladimir demands to know who beat Estragon a second time.
However, Estragon refrains from answering. He merely says that, no matter what happens, he's glad the day is over. Meanwhile, Estragon reveals that he heard Vladimir singing. For his part, Vladimir says that he sang because he missed Estragon.
Vladimir also admits that he was happy when Estragon was away. Now that he's with Estragon, however, he feels strangely sad. Estragon admits that, like Vladimir, he feels better when they're apart. Upon hearing this, Vladimir demands to know why Estragon always returns.
Estragon replies that he doesn't know. Vladimir then argues that Estragon returns because he doesn't know how to defend himself. He maintains that he wouldn't have let the others beat Estragon if he was nearby. However, Estragon reveals that Vladimir couldn't have stopped the second beating: his attackers numbered ten in all.
As the conversation continues, it appears as if Vladimir is blaming Estragon for the beatings he endured. This is odd and also disturbing. Although both men are friends, each offers the other little emotional support. One wonders why they remain companions, which is also likely a point Beckett is making.