The First Men

When the High-Dragon Tiamat created the first man, Adam was an imperfect, nude little fleshy being in the kiln of creation. But of Adam Tiamat took a rib and created Eve. The seeds of the Draconic Empire's demise were planted, and the fourth kingdom was born.
Humanity, the sons of air. The mutable creation of the other three kingdoms. Those whom had their design, their bodies, and their fates toyed with by dragon talons as if humanity was a tapistry on a loom, their lives string to be played with. The imperfect first creation was perfected and improved in time for the first pregnancy.
When Adam and Eve begat a child, he was named Cain. Or 'first' in draconic. The dragons studied the small, defenseless babe, and they were disatisfied. Almost as if purified, the young firstborn bore no taint of mutability. The dragons were displeased and forced the parents to couple again.
The second-born was named Abel for 'second'. This was the child the dragons saught. This was the being who carried such mutability monsters and soldiers alike could be bred, molded, and alchemically created from his loins. The dragons began to fashion a mate for Abel using one of his own ribs. A being of exquisite beauty and as mutable as the man she would mate with. Lillith.
Cain however, grew jealous. A lifetime of being sidelined. A lifetime of being unwanted and tested upon. A lifetime of torture and service for these scaled gods and his brother who had done relatively little was to be blessed with a reward. Cain raged and frothed. He fumed and plotted till, when his chance came, he slew his brother and set the body ablaze.
The dragons were furious. Their anger as strong as their flames and their will for revenge just as great. Cain was subjected to torture beyond human consideration. The eternal torture of prometheus paled before the flaying of flesh and collection of 'samples' the dragons inflicted upon cain.
Eventually however, mercifully, he was put down. Lillith, for her part, was left as a loose end. A wife without a husband, a creature created solely for breeding monsters for the dragons but with an empty womb. The dragons discussed what to do. Adam had since passed away, eve was in poor health. Their experiment was in danger. It was then Lillith herself helped decide all of humanity's course. She asked the dragons to fashion her a man. To create from her ribs a man equal to her. And in the mean-time, what did they have to lose by using the traitor cain's remains for 'tests'.
The queen of humanity spoke the dragons hearts well, and soon Seth was born. And while he was raised to be Lillith's consort and husband, Lillith began to beget children from cain. Monsters and beings who, over the eras of time, have forgotten their father but their mother has ever been un-disputed.
Unbeknownst to the dragons, Lillith hid three vials of blood. One of Ables, stolen in the dark of night. One of Seths, coerced easily while in bed. And one of Cain's, given to her by the dragons without qualm. When the Earth was split from eden, Lillith's hidden stash was upon the new minor plane as it hurtled into the abyss.
Eventually, enterprising mortals sought these vials. For their supposed immortality and ability to empower the imbiber.