Cornelia is the daughter of August Robertson and Victoria Robertson and the sister of Henry Robertson. She is married to Phillip Showalter and is having a secret romance with childhood friend Dr Algernon Edwards.
Cornelia is the head of the The Knick’s social welfare office and the board-of-trustees proxy. She is the one who insists that Dr Edwards is hired and threatens to pull funding for the hospital if he is not. When a case typhoid fever makes it way into an upper-class household, Cornelia, along with Jacob Speight try to find the cause.
Cornelia is married to Phillip Showalter who comes from a well off family who her father is desperate to please in order to do business with them. When Cornelia’s brother, Henry Robertson, reveals that their father, August Robertson, is losing his financial foothold on the West Coast is becomes clear to her that this is one of the main reasons for her marriage to Phillip. After Sister Harriet is called before a judge for her role in the backstreet abortions, Cornelia attempts to persuade Philip to help fund the ex-nun’s defense. Philip responds in disgust, unable to understand why Cornelia would support such a woman when they are trying to have a family of their own.
Dr. Algernon Edwards
Cornelia and Dr Algernon Edwards have a secret intimacy, which we see when he calls her “Neelie”. When Edwards opens his underground clinic in the basement of the hospital to treat the Negro patients, Cornelia is delighted and gives him her full support. The sexual tension between the two eventually gets the better of them and the pair end up having sex in Edward’s makeshift clinic in the basement. Unable to keep away Cornelia begins to frequently visit Edwards in his hotel during the night. The consequences of their affair become clear when Cornelia discovers she is pregnant with Edward’s baby. She approaches Edwards and begs him to perform an abortion to terminate the pregnancy, but he refuses saying “I can’t kill my own child!” This leads Cornelia to discover Tom Cleary and Sister Harriet’s underground abortion operation, and she has the pregnancy terminated by Sister Harriet. After the termination, Edwards distances himself from Cornelia, only for them to later share a kiss and rekindle their affair.
Cornelia’s father in-law, Hobart Showalter, has an unusual interest in Cornelia which comes across as almost incestuous. At one point he even suggests to her “Why don’t you start calling me dad?” Hobart gifts Cornelia with a pair of earrings belonging to his dead mother, which she later pawns in San Francisco in order to bribe to police to let her into a blocked off neighborhood full of starving immigrants. Hobart later offers to move Cornelia and Philip back to New York and into a stunning 11-bedroom apartment, at the base of Central Park. Desperate to get back to The Knick, she agrees only to find out she’s been fooled and the apartment is not yet ready. She and Philip now find themselves having to move in with the Showalters for the next five months. Hobart confronts Cornelia after he sends someone to follow her and discovers she has been investigating the death of Jacob Speight. He demands she stops and concentrates on making his son happy and getting pregnant.