Though many of our world’s more infamous monsters are long-since extinct, destroyed either by time or more deliberate endeavours, their touch can sometimes still be felt.
The existence of creatures and beings that might be considered monsters, in a crude and reductive taxonomy, seldom comes as a surprise for those with even a cursory acquaintance to the impossible. Indeed, a chance encounter with some fearsome and inhuman intelligence that cannot be accommodated within a more mainstream ontology can often be the spur that puts someone on the path towards an esoteric education. What can confound though, is that many of the famous species of classical monsters - the archetypes of folklore and myth that informed and inspired a shared representation of the fiendish - are notable in their contemporary absence: The most culturally pervasive examples of the sub- and super-human seem to have died out almost entirely.
Stories of vampires, werewolves and other creatures of their ilk (those who, despite their impossible abilities, nonetheless share a close kinship to the humanity whose image and aspect they selectively share) are, doubtless, vulnerable to the same exaggerations and amalgamations which lent themselves to the wild inaccuracies documented in mediaeval bestiaries. Nonetheless, there is good evidence that several demi-human species not only existed, but survived as variously viable subcultures within wider societies (sometimes for hundreds of years at a time) before fading out almost entirely across the eighteenth century. There are no clear reasons for these multiple and simultaneous apparent extinctions - neither malady nor crusade to whose banner either credit or condemnation can be attributed - but there are still instances of their human descendants creating somewhat more extraordinary issue.
The phenomenon is known as teratavism - a portmanteau of terata (a transliteration of a Greek word meaning ‘monster’) and atavism (a term for the reappearance of previously-absent ancestral characteristics) - though it can be mislabelled and misdiagnosed in any number of ways, depending on which species’ nature is being uncovered. Not following the typical rules which govern the heredity of things like eye colour, teratavism evidences as an irregular and unpredictable consanguinity; concerning traits which, while not consistently present at even a genetic level, are entirely dominant wherever and whenever they find themselves expressed. This means that although any of the strengths or abilities of a person’s inhuman ancestry might become apparent, they will not be tempered or lessened by their presence in an otherwise mortal form.
Despite being a result of genetic expression, at least in part, the interplay of the scientific and the supernatural in cases of teratavism means that the presence and appearance of even the most overtly non-human physical traits do not necessarily manifest at birth. This has seemed to be particularly evident where the mutation comes from a species whose inhuman aspect is covered by some kind of transformative metamorphosis (lycanthropes and amphibious merfolk being prime examples) or where an external catalyst causes the shift between their alternate form and appearing otherwise human. In such instances the revelation of abilities beyond the mere mortal may be triggered by puberty or other hormonal upheaval or by exposure to certain specific environmental conditions.
In cases of teratavistic vampirism, for instance, the presence of large amounts of spilled blood might trigger the manifestation of impossible strength or a mesmeric gaze. Nonetheless, whatever the trait, no matter how dramatic a transformation might appear, it occurs in isolation; an alteration of the baseline human code rather than the regression to a distinct form of life. Any supernatural abilities and their attendant mutations - none of which can be rationalised or explained by the purely physical mechanisms - do not come with accompanying instinctive or psychological changes or behaviours. Someone who develops a banshee’s ability to foresee deaths, for example, would lack their full-blooded ancestor’s compulsion to stalk the unfortunate and ill-fated whilst keening a chilling lament in warning.
As rare as teratavism is (best estimates and accounting for the fact that not all traits are easily observable put the rates at somewhere around one case in every three to five million people), there are no proven instances of it causing the weaknesses, failings and fallibilities which, to many, are as synonymous with any given monster as their strengths. Allergies and sensitivities to things like sunlight and silver (sometimes acute, even life-threatening) certainly exist, but their mysteries have been unravelled and explained as more common medical maladies. Some psychological conditions can present with a repulsion to religious iconography, or cause animalistic disinhibition under the wan light of a full moon, but these have only been seen concomitant with teratavism where a physical change has resulted in the delusion of a more complete transformation.
This disparity, the return of strengths without previous limitations, has given rise to some interesting theories around the origins of teratavism (particularly as it relates to the broader extinction of the creatures whose traits it restores). Given the relative instability of the historical cultures and communities of monsters - often living and dying at the extremely changeable whims of their parasitic and symbiotic relationships with human societies - some argue that teratavism represents an unsuccessful attempt at preservation. Endangered - either despite or as a result of being considered dangerous themselves - our not entirely dissimilar kin (whom we had come to label with the catchall ‘monsters’) recognised the inevitability of their annihilation and instead chose to chance their arms on the possibility of rebirth.
Interbreeding with humans, where that were possible, had taken place sporadically in the past; but the best records indicated that the results were inconsistent, an unpredictable lottery that would often produce offspring who were both too monstrous to be accepted in human society and not strong enough to survive outside of it. Instead pacts and bargains were entered into, the razing of whole species in order to cull the essences that would be infused into the boundless and fruitful children of mankind. There these potentials would take root, causing the occasional issue of scions who might restore their ancient species once the scrutiny of superstition had given way to the more hospitable mistaken certainties of modernity. Instead something went awry, and the only contemporary examples of what was are a handful of people with a disjointed collection of impossible abilities.