The Doc was a Rittenhouse agent who defected in 1972.
The Doc was born into Rittenhouse. At one point she earned a PHD in history at the University of Chicago. The Doc was responsible for keeping a mental roster of all the members of Rittenhouse.
She defected because she didn't want her son to be trapped in Rittenhouse as she was. Her husband and son had fled to Hong Kong and she was to reunite with them after helping Lucy and Rufus rescue Wyatt, with the help of the Black Liberation Army.