The Death of Gods?
No one knows when or how the Lukrovka came into being, or if they are a race unto themselves. They are related to Humans, and can breed with them. Some of the offspring of these unions are themselves half bloods, but they are usually humans and are often of poor health. The union of 2 Lukrovka is almost always fruitless, but on the very rare occasion of a conception, it is always another Lukrovka, with different characteristics