Amy Barksdale

Amy Barksdale is the youngest sister of Helen Morgendorffer and has often appeared in Daria fanfic as a support giver for Daria Morgendorffer. Her role and appearances in various fanfics are many times greater than her appearances in the series (three total).

Saint Amy
In the TV series, Amy Barksdale had a special relationship with Daria, offering her advice and moral support because in certain ways she appeared to be a grown-up version of Daria herself (see "I Don't" and "Through a Lens Darkly"). This element is taken to the extreme in some fanfic, leading to the archetype often called "Saint Amy," in which Amy rides in like the cavalry to rescue Daria from bad situations.

Trivia
In "Aunt Nauseam," Amy tries and fails to make peace between her sister's, prompting Daria to remark, "So, then, after Aunt Amy arrived to save the day and within three minutes had totally regressed into the same pre-school encounter group as her sisters...." The notion that Amy could "save the day" was not inherent in the episodes where she appeared; in "I Don't," she and Daria just bonded, while in "Through a Lens Darkly," she advised Daria to get contact lenses (which Daria ultimately discarded). Therefore, where did the writer of "Aunt Nauseam" get the notion that Amy could "save the day"? Possibly from Daria fanfiction.