How does Mary Warren change from act 1 to act 2 in The Crucible?

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...