Long before civilized man began murdering each other in the name of their Gods, there existed lesser Gods - the first Gods. Worshiped by ancient Egyptians, each for special powers. Like any Gods they grew jealous when mens attentions turned elsewhere and their statues and reliefs buried in sand and dust.
Many Gods faded from existance, needing their worshipers to keep them alive.
Others dwelled in darkness, their hatred of mankind burning and growing until revenge forged solidly in their brains. For all they had given to man, so they would take it away. Free will. Pleasures of the flesh. Experiencing the warmth of the sun on their faces. Children, love, respect.
The Gods take the lives of men, thrusting themselves into their mortal bodies. With bloodlust born of hatred, they use these bodies to murder, to rape, to wreak carnage. And to their delight, once bitten, a mortal forced to drink their tainted blood would soon be possessed by a hungry, waiting demon forever. Unnatural, immortal beings now roamed the earth, in constant struggle with their burning thirst for blood and their lingering humanity. These creatures became known to future generations of vampire as The Ancients.