Slightly more NSFW version here: Hemovore [TG/Vampire/Man-to-Cow]

Not prequels but sort-of related:

The creature was detained in the Washington area, red-handed, while in the process of feeding on a civilian. He claims to be European nobility, with diplomatic immunity for his actions as part of the Hungarian political entourage! After a cursory examination of its teeth, claws, and bizarre non-human biology, I am classifying him as a dangerous wild animal and detaining him as such. If there is political fallout, I will take responsibility. Not that anyone knows we have him.

The hemovore (we are not using the "V word", for the love of science!) appears to feed exclusively on blood. We are providing it with livestock. It demands human blood.

Such a fascinating animal! The more livestock it feeds upon, the more it resembles them. It is unclear whether this merely represents a genetic deterioration or if this is an evolved predator response that allows it to mimic its prey for ease of feeding.

We have restricted it to bovine specimens to better track its metamorphosis. Its pleas for human blood grow more frantic with every feed. It knows what it is becoming; what we are turning it into. Yet it cannot stop itself. It cannot go more than three nights before its hunger overwhelms it and compels it to feed.

The hemovore is an enigma. By most scientific metrics, it is dead. It has no pulse, no breath, and no body heat. Yet it is also alive. It moves, talks. Outwardly, it is a alluring, healthy specimen of its kind.

The one thing all the tests can agree on is that it is a cow, dead or alive, following weeks of forced feeding. A female holstein to be exact. Despite being unalive, it mimics many of the biological functions of life perfectly. Judging by the tightness of its udders, it is even producing milk.

Its mind remains fully intact and alert, always looking for ways out of its cage. It alternates between crying, begging, and threatening that other vam- hemovores will come for it.

I'm formulating countermeasures based on weaknesses in its physiology - the issue is that it has so many, I'm unsure where to start!

But the opportunity to gather extra specimens excites me!

Animal Control Report, March 7th, 1968

Filed by: Livia Holt, TFPD Forensic Zoologist