Peggy Olson has succeeded, professionally, in a man's world.
She's a junior copywriter at Sterling Cooper and has shown little remorse for the child she never cared for; her family takes care of the son she had with Pete.
Peggy hails from Brooklyn and is sort of Don's protege. He woos her into his new company at the conclusion of season three.
Peggy: Don, listen to me. What did you ever do that was so bad?
Don: I broke all my vows. I scandalized my child. I took another man's name and made nothing of it.
You'll have to believe me that I'll forget this. I don't want you treating me badly because I remind you of it.Peggy