However subjective it may be, the underlying forces of human fear do have substance, murky and grim. This fear, as it turns out, can relatively easily be bottled in its liquid state. The witches of old created a recipe to brew liquid fear, traditionally used to deter travelers away from their huts. Any creature with a crystal vial and a decent amount of free time can follow the steps to create what is known as the Elixer of Earthly Terror, a vile concoction of all the things that so transfix humanity.
Feather of goose, venom of snake (that one had been easy), fang of acrylic, rain, allowed to ferment for three full moons upon the tallest peak. After completing the arduous task of gathering the idols of fear, the demon Crowley followed the instructions religiously to break them down to their essence. And now, many hours of hard work later, he strolled proudly into the Soho bookshop carrying an ornate vial of the ebony Elixer.
The liquid in the vial was of an ink-like consistency, thick and goopy as it swirled around its container with each step the demon took. Beyond dark in color, blacker than black, it seemed to suck in all the light around it like a vacuum. The mesmerizing texture drew the eye in until one could look at nothing else as they are consumed by the darkness. It was like staring into the void. And the void stared back.
"Aziraphale? I'm here," Crowley called casually into the empty book shop, absently passing the vial between his bony hands.
Stepping out of the backroom, the angel to whom Crowley was speaking to appeared in the bookshop. Aziraphale flashed a quick smile, "Ah, Crowley. I was going to--" he paused and inquisitively eyed the pitch vial, "what is that you have?"
"What?" Crowley glanced down at the vial in his hands, "Oh, that. It's fear."
"Yep. What were you saying?"
"Why on Earth do you have fear?"
"To ward off trick-or-treaters," Crowley shrugged.
"Crowley," sighed Aziraphale, his tone more annoyed than anything, "this is a bookshop in the middle of London. I hardly think we'll get many--"
The angel trailed off as loud knock resonated from the front door, followed by the cacophonous giggle of children. Crowley raised an eyebrow but didn't say anything aloud.
"But you can't be serious. It--" Aziraphale glimpsed the ancient grandfather clock that oversaw the rows of antique books and declared, "it's four in the afternoon!"
"Remember when Halloween was about spirits and rituals?" Crowley reminisced, turning towards the door and gripping the brass handle, "Where've those days gone?"
"Trick or treat!" Chorused a group of children in shabby felt costumes. On the doorstep stood three kids masquerading as a pumpkin, a cat, and a rather offensive devil.
"Get lost," Crowley hissed, craning his neck to tower over the group. His words were met with blank, expectant stares.
"Go!" he urged after an uncomfortably long moment of no one moving. A collective mumble rose among the costumed children outside as the hesitantly shuffled away. Glaring venomously after them, Crowley frowned deeply.
"Well, I'll be," Aziraphale approached, peering outside.
Without taking his eyes off the departing trick-or-treaters, Crowley uncorked the vial containing the Elixer of Earthly Terror. A thin trail of dark vapor levitated out from the opening, glittering like dying stars. Behind his sunglasses, the demon's yellowed eyes glittered with malicious intent. With a scowl, he flipped the vial over in one hand and poured its contents onto the doorstep. A jet black stain appeared where the Elixer made contact with the pavement, looking more like a bottomless hole than a puddle.
"Are you sure that's wise?" Aziraphale hazarded as the last of the substance dripped out from the lip of the vial.
"It's fine. No one will even notice," as soon as Crowley finished speaking, a deafening rush of wind drowned out any further objections Aziraphale could have made. Howling as they scraped along the edges of the storefront, currents of icy wind suddenly and unnaturally gathered in the doorway.
Thick, black smoke rose in a wave from the essence of human fear currently residing at Crowley's feet, a wall of darkness ascending into the late-afternoon sky. Within mere seconds, the smoke had filled the sky so completely that it blotted out the sun, plunging London into a void-like gloom as the wind suddenly abated and the air grew eerily still. Any human unfortunate enough to be wandering the streets bolted for cover like rats from a torch, finding themselves overcome by an insurmountable sense of dread. Hastily, Crowley stepped back inside and slammed the door shut, turning his gaze to meet Aziraphale's bewildered expression with a nervous grin.