From researching alchemy (above are a few of the books I looked at) I found the idea of the hermaphrodite or The Rebis –
The Rebis (from the latin res bina, meaning double matter) is the end product of the alchemical “great work.” After one has gone through putrefaction and purification, separating opposing qualities, those qualities are united once more in what is sometimes described as the divine hermaphrodite, a reconciliation of spirit and matter, a being of both male and female qualities as indicated by the two heads within a single body. from http://altreligion.about.com/od/beliefsandcreeds/a/The-Rebis.htm
In order to understand the Alchemical and Hermetic traditions, a lesson in symbology is essential. Often, groups operating under these guises would mask profound philosophical truths in the form of images. One such image is the Great Hermaphrodite.
The symbol deals with “Hierosgamos“, or the union of opposites. On a very base level you could interpret the Great Hermaphrodite as a western equivalent to the Ying-Yang symbol of the oriental traditions; but the rabbit hole continues deeper. The alchemists, in their quest for philosophical gold, considered the world to be influenced and manipulated by a multitude of paired forces: wet and dry, cold and hot, sun and moon, male and female, proton and neutron, etc. When these opposing forces are harmonized and balanced through synthesis, creation is commenced. The Great Hermaphrodite is an amalgam of this union. from https://chemicalmarriage.wordpress.com/2011/03/23/the-great-hermaphrodite-explained/
I found so many images of this from the book Alchemy: The Medieval Alchemists and Their Royal Art by (first book above) and immediately came up with a narrative inspired by this idea of searching for knowledge and the cost being two heads.
I feel my narrative may change later, depending on the techniques I use to create the imagery but this is the basis of my narrative.