Knowing what I know now, I really think there are a lot of hints in there of things that were actually going on at the time. When reading Varney, I noticed a lot of alchemical references -- especially to the alchemical elements, like tin, silver, mercury, etc. Varney's eyes were described as being like tin, which I find to be an odd way to describe eyes. Varney also tends to target young, virginal women whom he marries and then sucks their blood and kills them.

Although "Varney" was written before Rymer became a Freemason, I think he was already dabbling to some extent with the occult. There are just too many hints throughout the book.