Abigail Williams is the leader of the group of girls who accuse innocent citizens of being involved in witchcraft. Abigail controls and manipulates the other girls to follow her lead after threatening them in Act One. In Betty's room, Abigail tells the girls,
Let either of you breathe a word, or the edge of a word, about the other things, and I will come to you in the black of some terrible night and I will bring a pointy reckoning that will shudder you. And you know I can do it; I saw Indians smash my dear parents’ heads on the pillow next to mine, and I have seen some reddish work done at night, and I can make you wish you had never seen the sun go down! (Miller, 20)
Abigail also enhances the hysteria of witchcraft by dramatically acting out in court, which makes the other girls believe spirits are also attacking them. Essentially, Abigail uses the girls' fear of being punished to her advantage and threatens to harm them if they do not follow her lead. Abigail then creates an hysterical environment in the courtroom, which affects the girls' mental state and perception of reality.
In regards to Abigail's relationship with John Proctor, she attempts to tempt him when he visits Reverend Parris's home at the beginning of the play. She still has feelings for John and even drinks blood to put a curse on his wife. Abigail also accuses Elizabeth of witchcraft in an attempt to get rid of her. She does not directly threaten John the way that she does the other girls but attempts to manipulate his behavior by attacking his wife. In both instances, Abigail uses her status and threats to manipulate and control both the girls and Proctor's behavior. However, Proctor decides to challenge Abigail rather than capitulate to her like the other girls.