Through the pact between races that became aitherions, a sacrifice of sheer power for a hope of peace was agreed upon by all. Using the last of their magic, the dragons made hands from hooves, and teeth from fangs, letting aitherions move amongst humans without being hunted.
Diminished from their original form, banshees could call forth their wings and talons, but lost their domination as warriors of the sky.
Werewolves did not betray their animal form but withered to the size of mere humans away from the full moon.
Terrified by their weakness, the aitherion races scattered, that rift enabling centuries of lost knowledge.
While each race tested their new limits, creating rituals, spells, talismans, and weapons to compensate what they had sacrificed, aitherion scholars did not begin to chronicle the common consequences of the pact until the 1300s. And, due to the continued mistrust between select races, a comprehensive study has yet to be made.
An early theory that has withstood the tests of modern science is the aitherion imitation of human in death.
Across all aitherion races, if an aitherion dies while in the guise of a human their corpse will present as human even with the use of modern forensic technology.
However, should an aitherion die while in true form (i.e. a harpy with wings extended, a werewolf in animal form, a vampire with fangs exposed) the dissolution of their their earthly form will occur according to race (i.e. fire, smoke, stone, mist, etc.)
This variance has led to the vulnerability of the races whose natural decay resembles that of humans, allowing their remains to be discovered and studied by humans several times in each century. Fortunately for all aitherions, the rarity of altered remains portrays a minimal existence, presenting the supernatural as extremely uncommon, offering most races an additional layer of secrecy and safety.
It just hit me that when they find the place Clara was killed, they'll actually find Clara. Oh. oh