Dr. Marcus Andrews is a surgeon and board member at San Jose St. Bonaventure Hospital. He serves as the head of the hospital's surgical department.
While he does have a personal life outside of work, Andrews oftentimes spends much of his time and energy focused on work. He has very high standards, and is always on top of everything that happens in his surgical department. He also displays a big ego. He often shows a fair amount of tension and stress, and rarely has a sense of humor, as a result of this. He originally has a major distrust for Shawn, using this as a means for wanting to take Dr. Glassman's position, as head of the hospital. This work focused demeanor, and lack of control of his ego, causes tension between Andrews and his wife. When he and his wife have trouble conceiving, Marcus becomes upset when the therapist suggests it may be due to a fertility problem in him. They also argue over Marcus using his distrust in Shaun in wanting to get Dr. Glassman booted out, for Marcus to have the hospital head position himself. Marcus also gets into a disagreement with Dr. Claire Browne, when he forbids her to apologize to a patient for misplacing a lab sample. Despite the frequent tense and egoistic behavior, he does occasionally show a caring, soothing side. This allows him to maintain his relationship with his wife, and to generally maintain relationships with Melendez and the surgical residents.
As the first season goes on, he forms a great deal of trust and belief in Shawn Murphy. He even eventually confronts Neil Melendez about his lingering distrust in Shawn.