Proctor is fearful of the court. He knows too well how vindictive and envious the townspeople are. All they need is a little incentive and who knows how bad things will get. He is angry at Mary for going to court and neglecting her duties as their servent . Mary changes because now she has power, which as a young girl and servant, she has never had anything like that before.
Proctor has very strong feelings against the court and Reverend Parris. He finds them both hypocritical and unfit to judge. Ultimately, he still is naive in thinking that this will all get straightened out without his having to go. Elizabeth is putting a lot of pressure on him to do the right thing and tell what he knows about Abigail.
Proctor is furious that Mary has disobeyed his orders to stay away from Salem. He is about to beat her when she tells him she will be going to court every day until she takes the steam right out of him by stating that Elizabeth had been accused.
Mary grows more confident as she asserts that it was her testimony that there was no indication of witchcraft in the house that has saved Elizabeth. This is not the same Mary that we saw in act one who was timid and frightened of her employer. Mary has gained power from her participation in the court proceedings and is enjoying the fact that Proctor no longer controls her.