Molly Fuller was born in Watford, Hertfordshire in 1899 to William H. Fuller (the famous England test cricketer) and Margaret Fuller. She enjoyed a semi-privileged upbringing and graduated from University College London with a degree in English Literature. Against her parent's wishes, she spurned a respectable career path and took a job as a reporter for a London newspaper. Within a few years she had worked her way up to the chief reporter on the social gossip column of a popular magazine, although she must publish under the pseudonym of Mungo J. Fuller to avoid the inherent misogyny in journalism at the time. Fed up with the empty charade that was gossip reporting, Molly took a job as staff reporter at the Daily Scoop, reporting on crime and bizarre events, a much more action-packed, exciting and fulfilling calling.

Molly is rather small and petite, and because of her proclivity to wear men's style tweed jackets and trousers, can often be mistaken for a teenage boy, especially when her wavy auburn hair is pinned up underneath a cloche hat. Although her physical frame may look weak, she moves with a purposeful kinetic energy. Her boisterous and bawdry mannerisms belie an educated and cultured interior.