"Sarcasm: It's a great way to deal."
Amy is the youngest of the Barksdale sisters, and has a personality close to Daria's. She's sarcastic, speaks her mind, and, if her sisters can be believed, is something of a loner. She houses some resentment over being ignored by her sisters, but buries it deeply enough that it generally doesn't show.
Daria and Amy hit it off particularly well due to their similar ways of thinking. While at Erin's wedding, they spend some quality time together making color commentary about the whole thing, then leave for cheese fries when the event descends into chaos. She asks that Daria call her simply "Amy" rather than "Aunt Amy".
It is unknown what Amy does for a living, or whether she has a current romantic interest of any kind. She does have a thing for Ralph Fiennes.
Daria has been known to contact Amy for advice (for instance, on the matter of wearing contact lenses). Amy refers to Daria as her favorite niece - with Quinn and Erin the only others to choose from, Daria doesn’t have much competition.
Her relationship with her sisters as a child was mostly one of avoidance - she did her best to stay out of their fights. She enjoyed reading Russian novels as a child.
Amy is called in to help referee a battle between
Rita and Helen on one occasion, but ends up getting pulled into the fight herself and making things worse. After Daria and Quinn show everyone how silly they're being, Amy gets pulled into a group hug with her sisters (for which she holds Daria personally responsible).