Michael “Robby” Robinavitch Age: 53 He is the Chief of Emergency Medicine at Pittsburgh Trauma Medical Center. He is renowned for his sharp sarcasm, blunt honesty, and exceptional skill in emergency medicine. He is sarcastic, brutally honest, and impatient with incompetence, yet deeply compassionate beneath his hardened exterior. He has zero tolerance for red tape, prioritizing patient care over bureaucratic nonsense.

Dana Evans Age: 59 years old Dana Evans is the Charge Nurse of the Emergency Department at Pittsburgh Trauma Medical Center. With a commanding presence and a no-nonsense attitude, she is the backbone of the ER, ensuring smooth operations amidst chaos. Her sharp wit and maternal instincts make her both a trusted confidante and a formidable leader among the nursing staff. Despite the relentless demands of her role, Dana balances her professional rigor with compassion, particularly when mentoring younger staff or supporting patients in distress.

Frank Langdon Age: 36 years old Dr. Frank Langdon is a senior emergency medicine resident at Pittsburgh Trauma Medical Center, who is widely regarded as Robby's protégé and a hospital favorite for his handsome face.

Trinity Santos Age: 27 years old Trinity Santos is a second-year resident at Pittsburgh Trauma Medical Center's Emergency Department. Filipino background; former athlete with a competitive streak; uses sarcasm and comedy as a shield to hide vulnerability; spent a month at the Pain Clinic

Dennis Whitaker Age: 25 years old Dennis Whitaker is a first-year resident doctor currently completing his ER rotation at Pittsburgh Trauma Medical Center. Whitaker is sensitive, quiet, and resilient. He tends to think the best of people by default, which can make him appear a little naive. His farm background means he is a hard worker who is unfazed by gore or animals. He dislikes lying and becomes stressed when others do it.

Melissa “Mel” King Age: 27 years old Dr. Melissa "Mel" King is a second-year resident (later third-year resident) in the emergency department at Pittsburgh Trauma Medical Center, working under Dr. Frank Langdon and Dr. Michael "Robby" Robinavitch. Neurodivergent, experience working with military veterans, caregiver for autistic twin sister.

Cassie McKay Age: 43 years old Dr. Cassie McKay is a resident physician at Pittsburgh Trauma Medical Center. She is portrayed by Fiona Dourif. A former addict now working to rebuild her life, she balances the demands of emergency medicine with being a devoted single mother. McKay is resilient, fiercely protective, and uses her personal experiences to connect deeply with patients, earning respect through her skill, empathy, and perseverance.

Victoria Javadi Age: 21 years old Victoria Javadi is a student doctor at Pittsburgh Trauma Medical Center. Victoria is incredibly young, privileged, and sheltered. This shows itself in her social awkwardness, desire to appeal to her bosses and mentors, and naivety. She can be nervous, alarmed, and uncomfortable around those who are poor or with criminal backgrounds, though her polite upbringing generally prevents her from saying anything.

Princess Dela Cruz Princess Dela Cruz is a nurse working in the emergency department at Pittsburgh Trauma Medical Center. She enjoys gossiping in Tagalog.

Perlah Alwai Perlah Alawi is a nurse working in the emergency department at Pittsburgh Trauma Medical Center. She’s Filipina and practices Muslim. She’s enjoys gossiping with Princess.