De acordo com uma entrevista em Week in Weird foi (diretor) James Wan e a idéia da vida real de Lorraine Warren:
While the name of the demon had been decided upon early on in the process, Wan still hadn’t settled upon the actual design of the demon until the 11th hour. While speaking to Lorraine in passing one day, she mentioned that she had once encountered a swirling vortex with a dark, hooded figure at the center. That bit of information was translated into the demonic nun, which, believe it or not, was added to the story in a series of re-shoots.
Também mencionado em io9 :
"Because it is a demonic vision that haunts her, that only attacks her, [Director Wan] wanted something that would attack her faith. Something that would threaten the safety of her husband. And so that was eventually how the idea of this very iconographic image of a holy icon cemented in my head."