It just appeared in the middle of town one day.
Applejack saw it on her way home, but she was in a hurry. She caught a brief glimpse of it. The perfectly smooth sides, charcoal gray and precise. But that was all she saw. That single look out of the corner of her eye as she galloped past. In her mind it was just another thing in a town filled with things.
By evening, half the town was gathered around it. They'd all seen it by now, had passed it on their way home like Applejack or had caught a glimpse through an open window. They circled it, speaking in hushed tones as if afraid they might awaken it. A brand new oddity for an already rather odd town.
“Monolith,” somepony—likely Twilight—said.
Very few of them knew what the word meant, only the feeling it gave them as it rippled through the crowd. A strange and very slight sense of vertigo. They all felt it, although nopony said a word as they let it pass over them. As quickly as it had come, it lifted like a cloud. They forgot in unison. Forgot who had said “monolith”, forgot they didn't know what it meant. They just stared at the structure before them, wondering where it had come from.
Twilight stepped forward. As a princess, she thought it was about time she took control. She opened her mouth to make a speech, something light but cautionary.
The words flopped out of her, loose and clumsy. They spilled from her like water from a burst pipe, insincere and nonsensical. She could feel the monolith pulsing behind her, throbbing and humming as the useless syllables crawled from her mouth. Twilight's gaze was drawn to it, even as she struggled to keep the crowd's attention. It was just so beautiful. Beautiful and unknowable, like the space beyond the void. In its darkness, she could see an entire universe. Looking deeper, Twilight could see a deep void from which creatures malevolent and impossible poured in a steady stream. The colors writhed and pulsed, much like the words she was failing to speak.
She reached to touch it. She was still speaking, but the static in her head had drowned out her words. Were they words? Twilight was barely conscious of her mouth moving, let alone what was coming out of it. She could only feel the monolith, could only hear its steady hum.
Lyra Heartstrings got there first. She reached to touch it, to feel its calming hum on her hoof.
Lyra vanished right before their eyes. One moment she was reaching to touch the monolith, the next she had disappeared. There was no fanfare, no muffled pop, no whoosh or scream or sharp intake of air. There was just the space where she had been, that final image of her burned into their eyes.
They all saw it. The expression of fear on Lyra's face as she reached out to the monolith, her eyes filled with tears. The way her hoof shook, the sheer terror that darted across her face a split second before she vanished. They saw it, but many of them did not comprehend what they had seen. They all stood there for a good minute, in awe of what was before them. As swiftly as it was seen, it was forgotten.
But then the crowd broke apart. They all felt it simultaneously, like the aftereffects of a tremor. A burst of static inside their heads, high-pitched and grating against the insides of their skulls. This wasn't fear. It was something harsh and primal, a long-buried instinct awakened by the droning hum.
Days passed. Ponies began to disappear.
Everypony knew it was the monolith. The hum—slow and steady—rippled through their bones. They always knew when somepony had been taken. The hum told them. Doors were locked, windows were bolted, entrances and exits barricaded from the inside. Communication with the outside world ceased entirely, as ponies feared attracting distant relatives or loved ones to the town. The streets emptied out.
The hum followed Applejack into her dreams. The inside of her head vibrated, her skull aching with a headache that never seemed to go away. Perhaps being somewhat far from town helped in a way, but the agonizing throbbing in her skull was the price she paid. She didn't know what had happened to her friends. Applejack tried not to think of it, tried to make herself calm even as the hum shook the inside of her head.
One night, she found Apple Bloom in the kitchen. The little filly had wandered out of bed at some point, despite Applejack having seen her fast asleep less than five minutes ago. Apple Bloom had descended the stairs on silent hooves, or perhaps the hum had drowned out her hoofsteps. Either way, Applejack found her little sister fiddling with the latch on the kitchen door.
Applejack sprang forward, a cry of alarm spilling from her mouth. She tackled Apple Bloom to the ground, wrapping herself tightly around the little filly's body. She'd hoped the shock would render Apple Bloom motionless for at least a few seconds, but Apple Bloom immediately began thrashing around. But the more she tried to escape Applejack's grip, the tighter her sister held on.
“No!” Apple Bloom screamed. “It wants me! I have to go to it! It wants me.”
Applejack was taken aback by Apple Bloom's strength. She was actually struggling to hold the much smaller pony in place. But she refused to relent, pressing Apple Bloom down with all her strength even as Apple Bloom tried to wiggle her hooves from Applejack's grip.
Even as Apple Bloom shrieked and pleaded, Applejack held on. She held on because she could see the terror in her sister's eyes, the tears streaming down her face, her desperation even as she struggled so vehemently against Applejack's grip. She knew what would happen if she touched the monolith. They all did. But it was so beautiful, so alluring, so unknowable and fascinating. It held their dreams hostage. Truly it was the most beautiful structure in all of Equestria, a sight worthy of the princesses' blessing.
Applejack's grip slackened for just a split second, her mind filled with the monolith. It was there for her. The monolith had come for her and her alone. She needed to go to it. It was calling to her, beckoning her, wanting her across the whole of life and death.
In that split second, Apple Bloom broke out of Applejack's grasp. She slammed her back hooves against the door, the wood splintering and breaking from the impact. Another blow caused the door to fly open, the flimsy locks and chains clattering to the floor. Then the unusually strong filly was gone, bolting through the empty doorway. She needed to get to the monolith. It had come there for her and she needed to go to it.
Her head clear for the first time in weeks, Applejack immediately threw herself through the open doorway. She raced towards Apple Bloom's retreating figure, shouting out her sister's name as she galloped. But Apple Bloom had a head start and knew exactly where she was going. In mere moments, Apple Bloom had reached the edge of the farm and completely disappeared from view.
By the time Applejack got to the monolith, it was too late. Apple Bloom was gone.
Applejack stood before the monolith, stood at the exact spot where her little sister had vanished. Her eyes were filled with tears. She stood there, helpless and angry as she stared at the uncaring structure before her. She didn't want to believe it. She didn't want to believe her sister had just been taken. Apple Bloom had been taken just like Granny Smith and Big Macintosh a few days ago. They thought they were safe out there on the farm. Perhaps they had been, but the hum had gotten them in the end.
She raised a hoof. Applejack was the only one left. The last Apple in Ponyville. She couldn't imagine what had happened to her friends. Perhaps she was the only one left in town, the final one to be summoned by the monolith.
But even as the anger welled up inside her, Applejack found herself admiring the monolith. So radiant, so wondrous and filled with secrets. It spoke to her through the hum, its voice almost indistinguishable from the droning. But somehow Applejack knew what it was saying. Its words filled her with primal fear, yet she stepped closer to the monolith. She reached out to touch it, almost choking on her sobs.
Nopony was there to see Applejack disappear. Nopony was there to see one of the strongest ponies in Ponyville break down, whispering her sister's name one last time before she was taken.
Two days later, the monolith disappeared.