Andrea is a 23-year-old recent college graduate with aspirations of writing for The New Yorker. Lacking any initial fashion sense or knowledge of high-society publishing, she accepts a demanding job as a junior assistant at Runway magazine. She rationalizes the grueling hours and toxic environment as a necessary stepping stone for her writing career. Her intense workplace environment constantly tests her priorities and her loyalty to her loved ones.

Miranda is the immensely powerful editor-in-chief of Runway magazine. Standing at five-foot-four and perfectly groomed, she holds absolute authority over her staff and vast influence in the fashion industry. She operates on a transactional basis with everyone around her and expects instant gratification for every request. She weaponizes communication, calling her assistants constantly at all hours to demand immediate results.

Alex is an inner-city schoolteacher and Andrea's devoted boyfriend since their college years. Altruistic and grounded, he provides a sharp contrast to the superficiality of the fashion industry. He acts as a voice of reason, pointing out how Andrea's job negatively alters her personality and monopolizes her time.

Lily is a graduate student studying Russian literature and Andrea's former college roommate. Vivacious and highly social, she enjoys the city's nightlife and casual romantic encounters. Underneath her party-girl exterior, she struggles with alcohol dependency, a problem that escalates while her best friend is distracted by work.

Emily is the senior assistant to Miranda Priestley. Fully indoctrinated into the Runway culture, she readily skips meals and basic necessities to ensure the office phones are always covered. She views her grueling job as a necessary sacrifice for future career success and expects the same level of fanatical devotion from Andrea.

Christian is a rising literary star who frequently attends high-profile social events in New York. Handsome and charismatic, he takes an immediate interest in Andrea despite her relationship with Alex. He frequently offers to introduce her to influential figures in publishing, blurring the line between professional networking and romantic pursuit.

James is a gay employee at Runway who takes pity on Andrea during her first few months. He provides helpful insight into the magazine's toxic culture and gently warns Andrea that her lack of fashion sense might cost her the job.

Jill is Andrea's married older sister. Living a conventional suburban life, she provides a sharp contrast to the Manhattan fashion scene. She is perceptive enough to see past Andrea's attempts to praise her prestigious new job.

Kyle is Jill's husband. He represents the normal, stable family life that exists completely outside the chaotic professional world Andrea experiences every day.

B-DAD is Miranda Priestley's current husband. The office staff secretly refers to him as "blind, deaf, and dumb" to explain why he stays married to such a demanding woman. Unlike his wife, he is consistently polite and fatherly to the assistants.

Jeffy is the keeper of the Runway fashion Closet. He helps Andrea assimilate into the magazine's strict dress code by sneaking her forgotten accessories and sample garments from old photoshoots.

Judith is the abrasive travel writer for Runway magazine. Known for her stutter and confrontational tone, she surprisingly develops a fondness for Andrea when the young assistant stands up to her bullying.

Madelaine is Miranda Priestley's new puppy. Her existence is initially a complete mystery to Andrea, resulting in widespread panic during the assistant's first assignment.