Daria fandom got a surprise in the very first fan-conducted interview with series creator Glenn Eichler, early in 2005, when it was revealed that Jake Morgendorffer was supposed to have had an older sister.
Fans of the series were long aware of clues that Jake was not an only child, such as Ruth Morgendorffer’s comment in “Jake of Hearts”, "raising his children". In The Daria Diaries is a photo of Helen, Quinn, and Daria dressed to go to the wedding of one of Daria's cousins, before the events of "I Don't" - since Erin Chambers is the only cousin Daria has on her mother's side, Daria thus has (at least) one cousin on her father's side.
Little is known of this unseen individual, though much is speculated. It is interesting that Jake himself never once mentions having a sister, or any other sibling, in canon. Still, her existence seems clear enough to make her a canon character.
Examples of Fanfiction Depictions
Prior to the Glenn Eichler interview, Richard Lobinske postulated that Jake had an older brother, Bruce Morgendorffer, two years Jake's senior. Background on Bruce appears in "Silver Lining" in the Falling Into College series.
In GlitterShrooms' "Phoenix" (a WIP), Jake is tormented by memories of his sister, who disappeared years earlier after running away from home. Daria and Quinn, however, have never heard of her before.
Mike Xeno's "Committed" gave Jake a brawny, bullying older brother, who has contempt for him and claims his bullying is an attempt to toughen Jake up. He physically resembles their father and is a US Marine; this resemblence and uniform briefly caused Jake to think Mad Dog had come back from the dead.
Charles RB's "God Save The Esteem" named her Eve Morgendorffer in its 31st story, after previously joking that nobody could remember her name. She's a highly passive woman, raised to know 'a woman's place', and is in a loveless marriage with a self-important bore named Captain Steele (from the Left Behind books, or rather Slacktivist's demolition of the same).
Sleepless created two lost sisters of Jake's, one named Joan, in his serial WIP, "Broken Connections" (see this section and this one). Joan became an Army nurse in Vietnam and was wounded by mortar fire. Jake hated her for being so close to their father, though he barely knew her. He never knew of the other sister, younger than he, whose mother was Korean.
Material from Interviews
- First March 2005 interview with Glenn Eichler on DVDaria, in which Jake’s sister is first mentioned
- Second March 2005 interview with Glenn Eichler on DVDaria, with a second look at the sister issue
Speculation, Story Ideas, and Plot Bunnies (PPMB)
- "Second coming of the New Ideas Thread"
- "New Idea thread (brainstorming for all)"
- "Daria - Scooby-Doo cross-over": Could Velma of Scooby-doo be Daria's cousin?
- "Time for another plot bunny (this time with bonus info!)": Could Darius be Daria's cousin?
- "Iron Chef: Daria's Half-Siblings on Jake's Side": related musings
- "Essay topics for the future": Could there also be an older brother of Jake's? (thread removed)
- "Iron Chef: Jake's sister!" on PPMB: discussion and more short fiction worth reading on the subject
- Brief mention of Jake's "older brother" in a fanfic(thread removed)