In some ancient civilizations the Wolf was a symbol of the underworld. In Egypt, the guardian of the dead was Anubis who was a wolf-headed god. The jackal portrayed as black was the symbol of both death and regeneration.
William is also the one who hid inside the suits and kidnapped and killed children, leading to the assumption that William Afton is The Purple Guy of FNaF 2 and 3 (he is killed at the end of the book when Charlie sets off the spring locks in his suit).
Pigtail Girl/Baby/William Afton. What if the girl that has the pigtails from fnaf 4 is the girl that we hear talk about playing with Baby throughout Sister Location. It would explain why Baby looks so much like her, it's s because she is William Aftons daughter, the man who CREATES the animatronics.