Rather than being the depiction of the real life serial killer, Fate's version of Jack the Ripper is an amalgamation of the numerous unborn children as well as those who died during an abortion manifested into a single entity, similar to how Nursery Rhyme represents the innocent imaginations and dreams of children across the ages. The serial killing of several women was due to Jack, representing the unborn children, wanted to find a solace for the fact that she was never truly "born" from the womb and never has a mother figure. Hence why she usually referred to her master (regardless of gender) as "mommy".