Dr. Olivette was the first overseer of Vault 81 and the only member of the "residential side" to know of the vault's true purpose.
When Vault 81 was built, it was designed in two parts, with a residential side, where the vault dwellers would live, and a secret wing, where scientists would conduct experiments on the residents. The goal of Vault 81 was to create a cure for all of humanity's illnesses. Dr. Olivette was picked by Vault-Tec from their candidate list after their prime choice, Duncan, fell ill.
Dr. Olivette was skeptical of Vault-Tec's goal and possible use of human experimentation, planning to blow the whistle if it was unethical. Upon receiving her full briefing, she discovered the complete unethical nature of the experiment as well as the company's relationship to major backers in the federal government, effectively eliminating the option of alerting any proper authorities.
Dr. Olivette was still determined not to let the residents of Vault 81 be used as guinea pigs, so on the morning of October 23rd, upon receiving the "call" to start notifications of staff and residents, she sabotaged the call list. While residents still received notifications, the science staff weren't properly notified and didn't all report in. Her plan mostly worked, but three of the science staff members still turned up anyway. Drs. Collins and Flint were living nearby and arrived with the general population, while an overachieving intern Burrow showed up to check when the next drill was.
Dr. Olivette was the only person on the residential side aware of the existence of the secret wing to Vault 81, with which she communicated through a set of connected terminals. As the three scientists worked to create their cure, Olivette watched over all of their data and personally had to approve the scientists moving onto Phase II, animal testing, and Phase III, human testing on unknowing participants.
Before the human testing stage began, Olivette made the choice to disable the scientists' equipment. This caused an abrupt halt to any future research, sparing the unknowing residents from potential harm. She likewise severed communication with the researchers, bearing the guilt of such an action but taking solace in the fact that they would have enough food and water to live out the rest of their days. She kept the vault's true purpose, and the existence of the secret wing, a closely guarded secret.
Dr. Olivette is mentioned only in Fallout 4.