Dr. Lucinda Sheraton

Dr. Sheraton is the Natural Philosopher (i.e. scientist) at Castle Warrick. She is Marcia's mentor/teacher as Marcia apprentices under her to become a natural philosopher herself. She is insatiably curious (as most natural philosophers are) and a bit absent-minded. She is brilliant but gets easily lost in her investigations.
Dr. Sheraton's parents died when she was young while they were experimenting with a formula for "Chinese fire medicine" (i.e. gunpowder). The resulting blast destroyed the castle's workshop and resulted in experiments with Chinese fire medicine being (temporarily) banned at Warrick.
Lucinda was apprenticed to her older brother to be a natural philosopher until he accidentally poisoned himself during her late teens (he was testing to see if adding arsenic to steel would make it stronger as adding arsenic to bronze does and breathed in an excess of arsenic vapors).
Many thought that after her multiple family tragedies, she would choose a different path but she continued on and finished her apprenticeship under Dr. Eberhardt, the natural philosopher at Castle Nordhaven. She returned to Castle Warrick at the age of twenty to take up the position of natural philosopher in her brother's place.