Quinn is a teenage girl with thin, tall, and has long red hair with bangs going across her forehead. For half of the series' run, she is seen wearing a pink midriff with a smiley face; during the second portion of the series, she wears a pink long sleeve shirt with a butterfly graphic that is cropped to expose her midriff. Throughout the season, Quinn wears blue bell-bottoms.
Unlike Daria, she values popularity and her appearance. Because she is afraid that others may see her in a light similar to the one they see Daria in, she claims she is an only child and denies the fact that she and Daria are sisters, usually telling people that Daria is "her cousin, a girl that happens to live with them, a foreign exchange student, etc."
Despite her cuteness and beauty, Quinn is very shallow and materialistic and she offers her time spent with Daria as a service to her parents in exchange for money. She is also quite air-headed because deep down she's afraid of being labeled as a "brain." For these reasons, she gives little regard to academic pursuits.
She is the vice president of the Fashion Club and is well-liked among her peers.
Quinn has a highly manipulative and mercenary personality when it comes to boys; she dates them for a brief time period for material gain and then dumps them when a better one comes along. She also strings along Jeffy, Jamie, and Joey so she can use them or feel better about herself by manipulating them into fighting over her. She is a very manipulative girl, often wheedling cash out of her father, undermining Sandi during Fashion Club, and getting Daria in trouble.
Despite this, Quinn has low self-esteem, confessing to Daria in Monster that the only things she likes about herself are her physical appearance and her popularity. She starts off having mute academic ambitions but ends up valuing her intelligence and her family, even hiring David Sorenson to tutor her. She is also loyal and caring, at one point confronting her friend Lindy about her alcoholism. Quinn is a very social girl, who very quickly integrates herself into the Fashion Club on her first day of school. She is also sexually conservative, turning down older boy's advances and refusing to pose sexually with boys in This Year's Model.
She begins to grow and mature in the last season. She becomes more sensible and slightly more caring to her older sister, especially after the events of Is It Fall Yet?, in which she fell in love with her tutor and learned that she doesn't have to act dumb and shallow to be popular. In the episode Lucky Strike, she even admitted to her class and to the Fashion Club that Daria is her sister and no longer her cousin.
Jake is very happy for and supportive of Quinn, albeit a little overprotective (asking Daria to make sure Quinn is okay on her first day). He is very gullible and easy to manipulate, Quinn usually gets money out of him. Quinn is closer to Jake than her mother when Jake has a heart attack Quinn sees a heart doctor and starts studying heart disease. Jake, along with Helen, expects Quinn to do well in school.
Helen is very supportive of Quinn's social activity, often cheerleading her decisions and being a genuinely supportive mother. Helen disapproves of Quinn's shallow nature, and has tried to gently steer her away by getting her to be more organized and trying to convince her that her self worth shouldn't be based solely off how she looks. This has also resulted in Helen bribing Daria to keep an eye on Quinn in social situations. In Psycho Therapy, Helen reveals disappointment in how Quinn 'has turned out.'
Daria and Quinn are rather resentful of each other, and are often in conflict due to their polarizing personalities. This animosity traces back to infancy. Both sides enjoy antagonizing each other, but despite their love of infuriating each other (and Quinn claiming to be an only child on several occasions), the two still love each other. Occasionally the two girls work together to achieve something, usually in the face of certain punishment. Despite being hilariously different, Quinn still turns to Daria for big sister advice, mainly for serious relationships or moral dilemmas.
Quinn is interested in three things; clothing, shopping, and being popular. She is the Vice-President of the Fashion Club, retiring only when Sandi resigns due to a sudden increase in weight. She also is a website creator, running Quinn's Cyberspecial Homepage, which gets 2,500 hits in the first three hours. She also is a writer, and wrote An Open Letter to Heidi Montag from Quinn Morgendorffer for a female-oriented blog called Jezebel. Originally, Quinn wanted to be a model, attended courses, classes given by Claude DeGregory and Romonica DeGregory.
Sandi Griffin serves as the main antagonist to Quinn. Despite a supposed friendship, the two are constantly undermining each other, and it's a pretty mutual situation. Early on, Quinn tried to usurp Sandi by asking Stacy Rowe and Tiffany Blum-Deckler what they thought of Sandi. Quinn and Stacy's dynamic is very strange; on one hand, Quinn allows Sandi to be left behind during a field trip, but conversely, Quinn doesn't date any boy without Sandi's approval.
Sandi in turn tries to nobble Quin backfire because she doesn't have the same social appeal as Quinn (her party held in conjunction with Quinn's in Daria Dance Party is a failure.) The friendship does have a measure of sincerity though; when Sandi gains weight and resigns from the Fashion Club, Quinn is the only member who still sees her on a regular basis.
Stacy is a genuine friend, the two often talk amongst themselves and share a significant degree of trust. Stacy is Quinn's first choice when she is only allowed to invite a single friend to sleepover in Of Human Bonding, and the two continue to see each other outside of Fashion Club in Fat Like Me. Quinn refuses to date any boy Stacy was in a previous relationship with, marking them down on a list. Stacy constantly seeks Quinn's approval, giving up her own tastes for Quinn's, once even dressing like her and suggesting they dye their hair the same shade. Quinn becomes increasingly uncomfortable, and flees Stacy's house for Jane Lane's instead.
Tiffany is one of Quinn's friends, but the two don't interact much outside of the Fashion Club. Despite this, Tiffany still supports Quinn over Sandi (though Sandi isn't there and it's for her own benefit). The two aren't very close, but still sleepover from time to time and maintain a cordial relationship. She is rarely seen in interactions outside of the Fashion Club but still remains as an important member of Quinn's clique. She's in the same class as Quinn, and is one of the 'popular girls'.
Quinn ends up graduating from college and marrying her college sweetheart. She drops her last name and becomes a stay at home mother. She ends up divorcing her college sweetheart and dropping her married name. Quinn has triplet sons- Tommy, Timmy, and Teddy- whom she takes care of and refuses to get a nanny for. She still uses hair extensions, and has remained in touch with Helen, Jake, Daria, and Stacy. She still lives in Lawndale, and runs a Youtube channel dedicated to deserts and skincare. The channel is called S'mores and Pores and has proved to be very successful. She still runs her website, Quinn's Cyberspace Special, and often updates it.
- Quinn was originally supposed to be a brother.
- In the Latin America dubbing, she was voiced by María Fernanda Morales.
- Quinn has four alter egos: Brainy Quinn, Sexually Active Quinn, Sexually Ambiguous Quinn, and Action Quinn