The intelligent, motivated and easy-on-the-eyes daughter of two over-achieving mothers, one of whom is a United States senator, Caitlin is an expert at hiding secrets. She hopes to follow in her mother’s political footsteps — that is, if the weight of her own secrets doesn’t crush her first.
On October 4th 2018, Sydney Park revealed Caitlin's new surname as Park-Lewis. Previously, her character has been marketed as "Caitlin Martell-Lewis", reflecting her book counterpart. The change may be a reflection of Sydney's own last name.
In the books, Caitlin is the adoptive daughter of two mothers, and the older adoptive sister to Taylor. Her brother committed suicide prior to the start of the series, which impacted Caitlin greatly. In the television series, one of her mother's is a senator and there is no mention of a sibling.
In the book, Caitlin is a Korean-American teenager, who is said to be very beautiful with a slim body. She has dark hair, pale skin, and brown eyes. In the show, Caitlin remains Korean-American, however, she has a shorter and curvier build. She also has more pigmented skin than her book counterpart.