At the Beginning of creation, two celestial beings descended from infinity and began their work to fill the unending. The Beings, known collectively as Dragons, used their Sparks of Life to transform this barren rock into a beautiful paradise, filled with beasts of the air, and of the field, and of the sea. They lifted up their eyes and saw that their creations were good, and decided that they could become as the Creator of all things. And so they attempted to do what none, other than the creator, had done before.

They attempted to create sentient life.

They did not succeed. At least, not quite.

The beings they created could walk, they could talk, they could even think. But they had not the spark of life, their empty husks contained no soul.
No matter how much they bickered and tried, they could not succeed in their self given task. what's more, The Creator confronted them of their sin, and they were punished.
no more would they roam the vast expanse of the cosmos, no more would they continue the Work they had been appointed.

as for the beings that had been born of the dragon's flames?

The creator filled them with the Spark of Life taken from the Dragons, and named them Human.

The youngest dragon, seeing the punishment as the chastisement it was, set about continuing The Work as best she could, teaching these new Human's things to prosper themselves.

But the eldest, grew bitter at her punishment.

The two sibling Celestials battled in the sky over the fate of men. They poured out their anger, their grief, and from their desires two new creatures were born.

Eons later, and the Knightly order of the Winged Chevaliers guard the realms of men from the great drakes, demons born of the Eldest's wrath, atop the Wyverns born of the Youngest's purity.