Castor Willow is somewhat of a tragic figure. At work he is a man in charge and wields his cane as his instrument of authority over his apprentice son. At home, he is a doting father to his headstrong daughter, Josephine. Castor knew Joe was not cut from the right cloth to be an Assameister, as hard as the boy tried. His untimely death posed a deep problem for Castor, and he dithered over a solution even as he contemplated his own pending demise. Castor mourns the loss of his son and the previous loss of his wife. All he has in the world is Josephine, brief comfort from Nell Barley, and his work. 

Castor first appears in Chapter Three, and is somewhat of a caricature. His backstory did not flesh out until Chapter Eleven, and his role amongst the Burghmeister’s is explained in more detail, and his dilemma and perpetual grief is called out.