From the beginning, Miller shows Abigail to be a lusty homewrecker. Her language is flirtatious and dangerously lusty for Puritan society. He adds in the narration that she speaks with a "confidential, wicked air" when she tells him of the dancing in the woods and continues with, "Give me a word. I am waitin' for you every night. I know how you clutched my back behind your house and sweated like a stallion whenever I come near! I saw your face when she put me out, and you loved me then and you do now!"
She plays on John's weakness as a man who wants to be needed and enjoys being appreciated. We learn later on in a conversation that Elizabeth has with John that Elizabeth never considered herself beautiful like Abigail, and that Elizabeth was afraid to entirely give herself over to John since she didn't feel worthy of a man like him. She has withheld affection, although she has not been unloving. Her fault is not being passionately free with John as Abigail was...this, and Abigail's youth and beauty were her weapons against John's desire to be wholly loved by his wife--thwarted by Elizabeth's own insecurities.
John and Elizabeth are sympathetic characters because this little "witch"--pardon the pun--has destroyed their home, their relationship, their town, and has caused the deaths of many respectable friends and family members. Abigail Williams is the epitome of evil in this story. Everyone else is her victim.