Mary Warren is depicted as a timid, insecure girl who is easily influenced by others and primarily concerned about her own safety. She is not a resolute, bold individual and eventually succumbs to peer pressure in act 3 when Abigail and the girls pretend her spirit is preparing to attack them.
In act 2, Mary Warren displays a myriad of emotions and attempts to stand up to John Proctor when he challenges the court's validity and instructs her to go to bed. Initially, Mary acts exhausted and emotionally drained from the day's proceedings. She even breaks down and cries when she informs John and Elizabeth that Goody Osburn will hang.
When John challenges the court's decision to hang Goody Osburn and asks for proof, Mary Warren takes offense and boldly asserts that she will continue to attend the proceedings because she is an "official of the court." Mary also stands up to John by saying she will "not stand whipping anymore" but quickly concedes when he raises the whip. Mary reacts by pointing at Elizabeth and claims that she saved her life. Once Cheever arrives with a warrant, Mary admits to making a poppet but does nothing to prevent Elizabeth from being arrested. At the end of the act, Mary informs John that Abigail will charge him with lechery and makes it clear that she does not want to testify against Abigail.
Mary's behavior in act 2 foreshadows her lack of courage and spineless nature, which is on display during her testimony in act 3. Mary begins by telling the truth but quickly changes her testimony when the situation becomes desperate. She is easily influenced by peer pressure and will say anything to avoid punishment and physical pain. Similar to the way she responded when John raised the whip, Mary undermines his deposition when she feels threatened. Once the tables turn and Abigail and the girls pretend to see her spirit, Mary alters her testimony and accuses John of working with the devil. Her cowardly personality and false bravado in act 2 foreshadow her lack of resolve during her testimony.