There were shadows dancing on the wall of the cave.
Light was what brought shadow into being; they were cast by its brightness and thrived in its absence, formed by blocking the brilliant rays from passing through space and time.
Where there was light, shadow existed by its side.
There were shadows dancing on the wall of the cave, and no mortal man, alchemist or not, could tell the true form of that which caused dark shapes to slide over the stone.
... for we see as through a glass, darkly...
Hohenheim was a scientist, a philosopher. He didn't believe in evil. That which others called "evil" was merely an imperfection; it was an absence of that which was good in a world where everything was created good, and therefore nothing was evil and evil was nothing.
He tried to repress a shudder as the thing strolled into the library, its lip curling at the stacks of books—reminders of the passion of the soul that had been burned out of its body and of the life which it could no longer claim. It padded toward him on cat-quiet feet, eyes narrowed in an expression of malicious good humor.
Hohenheim had known of his son's human failings and inner flaws. He had known how Lucas had resented being compared to his great alchemist father; he had tasted the boy's bitterness when others accepted him because of his good family name and not the sweat of his brow and fruit of his own labors. He had understood his golden child's pride, his unmistakable and yet completely forgivable envy; he had understood, and he had loved Lucas in spite of it all, because of it all—his imperfections of character had been so... so woefully, completely human.
Exactly what that thing which had risen from the spiraling array of divine proportions was not.
It leaned against the arm of Hohenheim's chair, leaning over his shoulder to study the book he held in his shaking hands, and strands of its death-darkened hair tickled along his cheek and neck. The sour smell of it—slight sulphuric, with stronger undertones of iron and ozone—made him gag and turn his face away sharply.
"Father... " it purred, breath cold against his skin, and then its hands were on his back, touching him, stroking over his lapels and twining in the loose sheaves of his blonde hair, and this time he couldn't stop his body's instinctive tremble.
"Envy," he said, not for the first time, "stop that. I told you not to touch me." He tried to focus on the words scrawled across the page before him.
"Call me by name," the thing breathed in his ear, and the hunger in its tone made his stomach twist horribly. "The one you won't say. Father mine, call me by name... Call me by his name." There was a revoltingly chill, wet touch against the curve of cartilage, and it purred again like a cat with a mouse under its claws, tongue rushing out with his words to lap up the human warmth.
Something in Hohenheim snapped, and he jerked free, shaking the thing off and quaking almost convulsively in terror and disgust. He wheeled around, staring at it with wide, fear-dilated eyes.
"Your name? Envy! Envy! Envy! " he shouted in rage, flinging the book in his hand wildly at it. Envy hissed and dodged it, baring its teeth like an animal. "I can only call you what you are! How thou are fallen from heaven, O Lucifer, son of the morning! "
Envy picked the tome up, flipping through the pages, and then he began tearing the leaves free, snarling as he did so. The papers fluttered to the floor like broken birds. "I know what I am! " it screamed back, flecks of foam flying from its lips. "Well thou hast named me, Father! Well, indeed; it was because of you that I sinned! You! " It took a step forward, and Hohenheim could see its own fury building to a fever-pitch. "For I had said in mine heart, I will ascend to heaven; I will exult my throne above the stars of God! I will ascend above the heights of the clouds; I will be like the most High! "
Hohenheim turned away, shaking his head and fumbling for the door like one struck blind. The thing was laughing softly behind him, but the sound was ragged and maniacal; it might have known where to strike to hurt him, but it sounded as though it had discovered too late a second side to the blade it had employed to do it. He stopped at the doorway, leaning heavily against it.
The shadow was dancing behind him, its sadism singing in its inhuman veins.
"The wages of sin is death," he muttered to himself before he slipped out.
"Thou wert brought down to Hell, O Day Star, son of the Dawn. The one who shone brightest fell the furthest, and God's favor lights upon you no more."