In the beginning of Great Expectations, why does Pip's convict, Magwitch, lie about his fellow convict in the ditch by hiding the fact that he has beaten him?
It is not until Chapter XLI that Pip learns all the personal history of the convict whom he encounters on the marshes as a child. In the early chapters of the Dickens's narrative, the orphan Pip looks upon the graves of his parents and is suddenly accosted by "a fearful man in grey." There in the mists that are symbolic of ambiguity and confusion, Pip is ordered to bring this man a file and some "wittles" without telling anyone if he wants to live. If he fails to do so, the convict warns him, Pip's "heart and liver shall be tore out, "roasted and eaten." In addition, the convict tells Pip,
There's a young man hid with me. That young man hears the words I speak. That young man has a secret way of getting at a boy, and at his heart, and at his liver. It is in wain for a boy to attempt to hide himself from that young man.
Further, he tells Pip that he is keeping that man from harming Pip, but it is difficult because the man wants to harm Pip. Clearly, the convict uses the other man as a threat to Pip in order to frighten the boy into obtaining the file and food for him. Also, he does not want Pip to think that the man will come forward and reveal himself. In this way, Pip will only bring enough food for the first convict.
As Pip returns the next morning, he mistakes the second convict, (whose face is badly bruised) for his convict of the night before and taps the man on the shoulder, but the convict runs off. Then, when Pip mentions this man, the first convict becomes very agitated, grabbing the file and working frantically upon his leg iron. Pip slips away and hears the file scraping the leg iron "like a madman" in the distance. It is apparent that the convict wishes to free himself and get to the second convict for some reason. However, Pip does not learn the truth about these men until much later in the narrative. All he can piece together is that they may be enemies; so intense is the first convict upon catching up to the second that he tries to quickly free his leg so that he can reach the first convict for some reason. In truth, the two convicts are foils to each other as the second convict sorely lacks the virtues of the first convict, Magwitch.