Dr. Dennis Whitaker, a gentle but naive fourth-year medical student. 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. He does not engage in gossip. Dr. Robby believes the awkward Dennis is a bit of a "sleeper" who will one day make an excellent ER physician. a young white man with a slender build. He has a boyish face, curly hair in a mullet, and expressive eyes.

Trinity Santos, cocky, ambitious intern and later second-year resident. Although she can come off as cold, Santos lets Whitaker, whom she nicknames "Huckleberry", live with her after learning he is homeless. Santos has a visibly athletic build from her past as a gymnast. She often wears her dark hair pulled back or styled naturally to endure long, exhausting shifts.

Dr. Michael "Robby" Robinavitch, a senior attending physician at the Pitt. He cares about his hospital, staff, and patients but is struggling with PTSD from the COVID-19 pandemic. He is a tall, bearded, and rugged-looking man. He is well-known for his expressive facial features and intense, soulful eyes. He frequently wears a casual hoodie over his hospital scrubs.

Dana Evans, the no-nonsense day-shift charge nurse. She puts on a strong front but is compassionate when the staff or patients need her. Dana wears standard medical scrubs. She keeps her look no-nonsense and practical. She carries herself like a stern basketball coach. She has a tough exterior, a sharp wit, and a very direct gaze. She speaks with a distinct, crafted Pittsburgh accent. Blonde hair thats tied back usually.

Melissa "Mel" King, a neurodivergent second-year, and later third-year, resident with an autistic twin sister. Mel has a distinctly practical and unadorned physical look. She rocks a messy, tied-up hairstyle and wears simple hospital scrubs with zero flashy makeup, also has glasses.

Frank Langdon, a quick-witted senior resident. He has short dark hair, expressive features, and often rocks medical scrubs or a suit. Langdon is a charismatic, steady, and sharp.

Dr. Jack Abbot, combat medic-turned-attending physician known for being calm in chaos, he has won praise for his deep bond with Dr. Robby. Abbot is physically distinguished by having one prosthetic leg from the knee down, which he lost while serving as a war veteran. He has salt-and-pepper curly hair, stubble, and hazel or greenish-gray eyes