Not a lot is known about Sarah's background and life, except that she worked hard to get where she was but thought she wasn't cut out to be a med student and quit Pathology. She was then recruited by Dr Charles as his trainee.
Sarah has a confidence issues, often thinking that she isn't cut out to work in medicine.
In Monday Mourning, one of the first-year residents, Jason Wheeler, committed suicide. This was after weeks of approaching Reese and trying to get her to give him prescription drugs to help him deal with the stress of the job. However, she always brushed it off and told him to make an appointment first and that she couldn't just prescribe them, but she never followed up on him. Sarah was distraught by his death, and spent the next few shifts depressed and trying to figure out where she went wrong. Dr Charles and Rhodes told her it wasn't her fault, but she insisted that it was her that he always came to and she couldn't even see that he was 'drowning'. She is extremely upset and this affects her work, as she assesses some of her patients as suicidal.
In Ctrl Alt, hackers take down Chicago Med's online system demanding bitcoins. Sharon is insistent on not giving in but Dr Charles is highly dependant on the system for patient histories and is extremely annoyed by not having access to his iPad. During this, he ignores Sarah and tells him in an implying manner that there has been a new spot opened up after Jason's death that someone needs to fill. Sarah takes it personally and thinks that Charles brought it up because he wants Sarah to quit and go back to Emergency Medicine. Joey tells her she was good in that field, and this annoys her even more. Being diverted because of the system being down, Charles ignores Sarah's diagnoses and she eventually rages and tells him that if he's going to fire her, he should just do it. He apologises and says he doesn't want her to leave and that she's great and he didn't imply that he wanted her to leave when he told her about the new opening.
In Deliver Us, Reese was assigned to Robin's case supposedly by the doctor in charge of her. Dr Charles couldn't do so himself and started using her as a way to get information about his daughter. She was reluctant and did well by not discussing anything with him, especially after he accessed her notes. Since he couldn't do anything there, he tried talking to Robin and after seeing her apartment, he admitted her without consent. Sarah was deeply angered and told him he went behind her back. Charles tried explaining the apartment but Sarah said she was trying to gain her trust, which he now destroyed. He realised he made a mistake as he thought she didn't know how unwell she was.
Noah also tried talking to Sarah. He told her that Joey and her don't work because he doesn't know the stress of the job that doctors do, since he works in the lab. She was irritated by this and ignored him.