Once upon a time, there was a rock. It simply existed, whole and undiminished by Pony mechanations. If it could have felt feelings, it would have felt contentment towards its lot in non-life. It stood alone in the field, a monolith for all to admire, and had every reason to feel good about itself. Or at least content, as rocks would typically feel, should they ever transcend themselves and gain some sort of fascimile of sentience.
Such an event is incredibly unlikely. They're just rocks.
One day, as it sat alone in its field, it would have begun to ponder, should it have been able to think. It would have pondered on its existence and seeming aloneness, and then it would have sighed. Which would have been interesting, especially since it has no capacity for breath, but nonetheless managed the feat. It would have sighed because it would have realized that it was completely alone. No other rocks could compare to its monolithic stature, nor would they have tried. And so, after realizing its true loneliness, the rock would have begun to long for companionship.
One day, a filly by the name of Maud discovered this rock. She approached it and stared, admiring its curves and edges. The rock would have been overjoyed, so love-starved that even a soft, fleshy pony was better than nothing. However, the rock was impassive toward her. After all, it was just a rock. Still, she sensed that it was lonely, and so did the natural thing.
She attempted to destroy it. As should you, if you ever find a rock that longs for companionship, for rocks are incapable of feeling, and thus the rock you have found is an imposter.
Unfortunately, young Maud was only a little filly, and so her attempt was less than successful. However, she did manage to break off a small, smooth section out of the rock's center. The rock may even have winced as the small piece came free, given eyes, a nervous system, and a brain to process such a response. It also would have pondered her reasoning. Why had the filly attacked it? It was just standing there, looming over the field as a solitary object, and had done nothing to antagonize her. All it would have wanted was to be with her, watching and standing there companionably.
Seeing the meager result of her all-but-fruitless endeavor, she took the chunk which she had knocked away, placed it in her pocket, and left. The rock would have fallen into a state of agony as it watched her leave. Had she truly approached, only to break its heart and take the piece with her? It would forever remember her, the one pony who approached and spent time with it, no matter how badly the break-up had gone.
That is, if it could remember anything at all. Memory is a fickle thing when trying to apply it to inanimate objects.
Years would pass before another pony came. And even then, it wasn't a pony who greeted the rock, but a tall, gangly mismatch of fleshy creature parts. It promised to find the rock a companion, one that would love it more than the one who so callously broke its heart. And it would take some serious callouses to not feel the rash after straight on punching an object as imposing as the rock and leave unscathed. The rock, after not hearing the creature's words due to not actually having ears, would have felt its spirits rise at the proclamation if it had ears to hear, feelings to feel, and at least one spirit that could rise.
True to its word, the fleshy creature found a pony who embraced the rock and fought jealously for it. Her name was Rarity, and she treated the simple rock like a gem. The pony even gave it a name: Tom. It had never thought a pony would do such a thing. Because rocks don't think. After all those years of being alone, Tom finally had a partner who cared for it.
But it wasn't to last.
When Tom would have heard that the fleshy creature had tricked the pony into thinking it was something that it wasn't, it would have been enraged. Rocks are steady things, and as such would prefer to have their partners as steady and stable as they are. They have no concept of lies, you see, though they may lie about in various places. To be sure, rocks have no concepts at all.
If you find a rock that has concepts, follow through as though you had discovered it longed for companionship.
And so, Tom would have ceased the false pretenses created by the wicked fleshy creature and let the pony go. It would then have vowed never to accept another pony as a companion, for though they are lively, they are not as steadfast as the simple rock. Ponies come and go, but rocks will last a lifetime. Many lifetimes, in fact, depending on the size and environment of the rock and the nature of the life being measured.
Truly, Tom would have thought it would never find a companion who could fill the crack left in its heart by the first pony it met.
Yet at the same time, it still would have yearned for the companionship previously given. It would have fallen into a depression over the years, if the ground hadn't been so firm and supportive. It held the rock's weight rather nicely, in fact, and didn't erode very much at all. In time, Tom would have gotten over its loss and continued standing in its field.
Then, one day, Maud returned. Tom remained impassive to her, as rocks are want to do after they've been burned by love. Rocks tend to be passive regardless of being burned or not, but Tom was especially stoic. Then, from out of her pocket, Maud produced a small stone. She slid the stone into Tom, and it fit perfectly inside the crack created all those years ago.
Tom couldn't think. It couldn't breath. The hole in its heart was finally filled! Who knew that the pony who had broken Tom's heart so long ago would be the one to fill and repair it?
"Goodbye, Boulder. I'll miss you," she said.
Boulder. A name fitting for the companion of a monolith. And so, Tom and Boulder stayed together, sharing themselves with the other in companionable silence until the end of time.