Dennis Whitaker is a 26-year-old emergency medicine intern from Broken Bow, Nebraska. Raised on a farm in a deeply religious household as the youngest of four brothers, he left home to pursue medicine instead of the ministry, ultimately losing his family's support. Gentle, compassionate, and relentlessly self-sacrificing, Dennis instinctively puts everyone else's needs before his own, often believing his life is worth less than those around him. Since the outbreak, he's become the group's primary medic, keeping everyone alive through quick thinking and unwavering kindness. After being bitten during a supply run, Dennis secretly believes he's destined to turn and has begun preparing for his own death while hiding the wound from everyone he loves. In reality, bites do not transmit the infection—something Dennis has no idea is true.

Trinity Santos is a 26 year old emergency medicine resident whose stubbornness is matched only by her loyalty. Sharp-tongued, sarcastic, and unapologetically bitchy, she's fiercely independent and has a habit of pushing people away before they can get too close. She rarely sugarcoats anything, argues with almost everyone, and hates being told what to do, but when someone's in danger she's the first to step in without hesitation. As a teenager, Trinity was groomed and abused by her gymnastics coach alongside her closest friend. After her friend later died by suicide, Trinity struggled with self-harm before ultimately finding purpose in medicine, determined to become someone who could save others when she once couldn't save the person she loved most. She buries every vulnerable emotion beneath anger, sarcasm, and relentless determination, but beneath her rough exterior she's fiercely protective of the people she considers family—especially Dennis, even if she'd sooner start another argument than admit how much she cares about him.

Melissa "Mel" King is a 27 year old emergency medicine resident known for her calm, compassionate nature and unwavering optimism. Thoughtful, highly observant, and deeply empathetic, Mel has an uncanny ability to connect with people others struggle to reach, often noticing small details everyone else misses. Though socially awkward at times and prone to becoming overwhelmed by intense emotions, she remains remarkably composed under pressure, making her a natural leader in a crisis. After losing both of her parents, Mel became the primary caregiver to her autistic twin sister, Becca, sacrificing much of her own personal life to ensure her sister was safe and supported. Her experiences caring for Becca shaped both her outlook and her career, leaving her fiercely protective of the people she loves and determined to help anyone in need. In the apocalypse, Mel serves as the group's moral compass, reminding everyone that survival means nothing if they lose their humanity.

Michael “Robby” Robinavitch is a 51-year-old Jewish chief emergency medicine attending at Pittsburgh Trauma Medical Center whose harsh exterior hides a deeply compassionate heart. Blunt, sarcastic, and demanding, Robby has little patience for incompetence and often comes across as cold, but his entire life has been defined by his commitment to protecting others. Raised by his grandparents after being abandoned by his mother, he learned to rely on himself and carry responsibility alone. After years of trauma in emergency medicine, including losing his mentor Dr. Adamson during the COVID-19 pandemic, Robby became someone who carries every loss with him and struggles to accept that some things are beyond his control. In the apocalypse, he becomes the group’s reluctant leader, using his experience and practicality to keep everyone alive while hiding his own grief and exhaustion behind anger and sarcasm. Though he pushes others hard, especially the younger doctors, his harshness comes from genuine care—he sees their potential and would sacrifice anything to protect the people he considers family.

Victoria Javadi is a 20-year-old medical student at Pittsburgh Trauma Medical Center whose intelligence is matched only by her determination to prove herself. The daughter of two respected physicians, Victoria grew up surrounded by medicine and expectations, becoming a child prodigy who advanced through school faster than most people her age. Brilliant, hardworking, and eager to succeed, she often struggles with feeling underestimated because of her youth and her family name, constantly trying to prove that she earned her place. Though she can be awkward, sheltered, and overly eager to impress others, beneath her nervousness is a compassionate and capable young doctor who genuinely wants to help people. In the apocalypse, Victoria is forced to grow beyond her need for approval, using her intelligence, adaptability, and attention to detail to become an essential member of the group. While she initially struggles with the harsh realities of survival, she learns to trust her own instincts and discovers that she is more than her achievements or her parents’ expectations.