Main Characters   

Lee Sung Kyung, 29 (M.D.) 

• Attending Cardiologist at SNUH. Was offered the position of Chief in her department but turned it down because the thought of people calling her "Chief" made her feel old and sappy. Besides, no one wants to sit around in an office doing paperwork all day. One of the best Cardiologists in the country but keeps a lowkey profile, though she has established her bragging rights. 

Nam Joo Hyuk, 29 (M.D.)

• An attending Pediatric Surgeon at SNUH. Born and raised in Busan but he and his family moved to Seoul just as he was starting high school. Started out as rivals with Sung Kyung when they first met, competing over who was the smartest overall but ended up becoming best friends. Hails from a family of legendary surgeons who own the hospital he's currently employed at. Been having feelings for Sung Kyung for a while but is too scared to pursue those feelings. 

Supporting Characters

Lee Jong Suk, 31 (M.D.)

• Chief of Cardiology at SNUH. Sung Kyung's over-protective older brother that would do just about anything his little sister asks. Has a bubbly, outgoing personality which is the polar opposite of his little sister. As much as he hates admitting it, he cares a little too much for his patients and always gets emotionally attached. 

Yoon Kyun Sang, 31 (M.D.)

• Attending Neurologist at SNUH. He and Jong Suk have known each other and have been the best of friends since birth. Was the supposed heir to a tech empire but he passed the position onto his sister since he had no interest in running a business and opted to save lives instead. 

Kim Go Eun, 29 (M.D.)

• Attending General Surgeon at SNUH. Sung Kyung's ride or die work-wife and "wifey" in general. The know anything and everything about each other. Everything. She will not hesitate to cut a if anyone dared to question her abilities. 

Choi Tae Joon, 29 (M.D.)

• Attending Otolaryngologist at SNUH. Is a very bold and confident man who takes great pride in his work. He was born into an upper-class family but does not like to reveal his wealth to others. He was put on the same team as Sung Kyung on their very first day at work as interns and they hit it off right away. After much pestering, he finally managed to convince Sung Kyung to let him be her roommate.

Park Shin Hye, 29 (M.D.)

• Attending Orthopedic Surgeon at SNUH. She worked very hard in her youth to get into South Korea's best university and succeeded by landing a job in her dream hospital during her residency. She might not look like it on the outside, but she has a black belt in Tae Kwon Do and literally breaks bones for a living. She also fixes them of course. 

Kim Ji Soo, 29 (M.D.)

• Attending Trauma Surgeon at SNUH. Joo Hyuk's most trusted and best friend since they were little kids. They met at such a young age because their families were very close and had history together. Is considered the baby in the group. 

Seo Kang Jun, 28 (M.D.)

• Attending Anesthesiologist at SNUH. Sung Kyung's most trusted Anesthesiologist and in her personal opinion, the best there is. He will assist in all of her surgeries as per her special request, depending on their schedules. They might've slept together once...maybe twice but they don't talk about that. 

Lee Family

Lee Chul, 58

• Chief of the Korean National Police Agency. Father of Jong Suk and Sung Kyung. A man of law and justice. Undoubtedly loving towards his family and would go to extreme lengths to protect them from harm. 

Kang Soo Jin, 59

• Human and civil rights lawyer. Mother of Jong Suk and Sung Kyung. She and her husband decided to adopt Sung Kyung when they found out another pregnancy would have been fatal to her. They have since then treated her like their own blood, loving her unconditionally and never once treated her otherwise.

Nam Family 

Nam Woo Sang, 62 (M.D.) 

• Chief Executive Officer (CEO) of Seoul National University Hospital, specializing in Cardiology. Joo Hyuk's father. One of the wealthiest people in all of South Korea and does not fail to act like it. 

Jung Min Ji, 60 (M.D.)

• Chief of Surgery at SNUH, specializing in Orthopedic Surgery. Joo Hyuk's mother. A well-known general surgeon and is a role model to those practicing medicine. Some might even call her a Goddess. 

Nam Hye Jin, 33 (M.D.)

• Chief of Neurosurgery at SNUH. Joo Hyuk's older sister and the oldest among 3 siblings. 

Nam Jun Ho, 26 

• An architect with big dreams. Joo Hyuk's little brother. Calls himself a "badass rebel" since he chose to pursue something other than medicine which infuriated his father. Looks like a cinnamon roll and is an actual cinnamon roll.