She earned her nickname many years before the events of The Spook's Apprentice, when she opened a home for young women who were struggling to care for their infants. Unbeknown to the home's residents, Mother Malkin in fact had no intention of caring for these women. When missing people reports came about within the county, locals went to investigate, only to find the bodies of mothers and infants drained of blood. It is assumed Mother Malkin used this blood she had collected in some form of Dark Magic during a ritual.
Mother Malkin preferred to employ the use of Blood Magic, unlike her niece, Bony Lizzie, who got by using Bone Magic. Mother Malkin was, as suggested by the name she was known by, of the Malkin clan.