Oathbreakers are the servants of The Plague Doctor, and are named in reference to the Hippocratic Oath.
There are two varieties of Oathbreaker, Plague Bearers and Mad Doctors.
Plague Bearers, or Night Surgeons, work to ensure that disease is spread throughout the population. They often pose as nurses, pharmaceutical salespeople, or back-alley doctors. Others spread disease through their occupations in food service or by encouraging/holding pox parties instead of vaccinating their children. Anyone intentionally spreading disease can be a Plague Bearer. Unlike the Mad Doctors, it's not a position limited to the medical profession. Aside from their work, they usually function as normal members of society. Plague Bearers sometimes have the Stick and Serpent symbol tattooed on their body or worn on jewelry or used in some manner of decoration in their home or office, both to honor their master and as a thinly veiled reference to their secret life.
Mad Doctors usually occupy higher positions in the medical industry than their counterparts, being surgeons, scientists, doctors, and psychiatrists. They are more specialized in spreading disease than Plague Bearers, and will often kidnap people and use them as guinea pigs for twisted experiments.
A notable Mad Doctor goes by the name of Dr. Beakman.