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"I get weepy when I see two people in love."
The Scorch Trials

Ponytail is one of the Cranks Thomas and Brenda meet in The Scorch Trials, along with Blondie. She has her hair in a red ponytail, which was how Thomas came up with the nickname Ponytail for her. In the books, she wears a low cut shirt and threatens Thomas and Brenda with a screwdriver when they do not want to join the party.

In the movie, it's not confirmed that the woman is Ponytail. Instead of a red ponytail, she has blonde hair. She's not past the Gone yet so it's not obvious that she is a Crank.