In act 1, Mary Warren is described as subservient, naive, and lonely. She is easily dominated by Abigail and is mocked by Mercy for her "grand peeping courage." When she sees John Proctor, her employer, she is almost speechless with embarrassment and fear but manages to say that she is...
just going home. Proctor upbraids her and threatens her with violence, to which she has no reply.
In act 2, we hear of the change in Mary before she enters. Elizabeth says that she could not prevent Mary from going to Salem, though John had forbidden it. Mary had replied:
I must go to Salem, Goody Proctor; I am an official of the court.
When Mary returns, she has a new self-assurance which is reinforced by the eager questioning of the Proctors. When John forbids her to return to court, Mary replies:
I must tell you, sir, I will be gone every day now. I am amazed that you do not see what weighty work we do.
Mary's self-importance at her new position of power is increased by social snobbery. When she refuses to tell Elizabeth who has accused her, she adds:
I only hope you'll not be so sarcastical no more. Four judges and the king's deputy sat to dinner with us but an hour ago. I - I would have you speak to me civilly, from this out.
She has been keeping company with much grander people than the Proctors and still shines with their reflected glory.
Mary's confidence is so recently discovered that it occasionally falters. In a rare moment of comedy, she refuses to be sent to bed by John, then immediately decides that she wants to go to bed anyway. However, the arrogance and impertinence with which she addresses her employers is already a world away from her cowering, tremulous demeanor in act 1.