Twilight first realised things were wrong when, all of a sudden, she felt something strange beneath her. It wasn't the softness of her bed in the Library, but something else, cold and wet. Slowly, she opened her eyes, taking a moment to adjust to the light levels. And here, to her shock, she found herself in a place unknown to her. Grass was beneath her, and all around from the looks of it. She got to her hooves, looking in every direction, but she was all alone here. The air was cold, and her breathing made that clear with every small cloud of vapour that now left her mouth.
"H...hello?"
She called out, but nopony answered. Instead, all she got was silence, save for the gentle breeze around her. But, her attention was soon drawn to something else, far from her. It was a small hill, right on the horizon. Twilight hesitated, but for the time being, it was all she had to go on. So, slowly, she took a step forward. Then another, and another, and another, until she finally started a more regular walking speed. However, it was not long after she did this when she noticed something that, frankly, she should have noticed right from the start, for as she looked upwards, her eyes widened with disbelief.
"What?!"
The sky was quite unlike anything she'd ever seen before. On one half, to her right, was bright daytime, with the sun shining brilliantly in the middle of it. To the left was the night, with a beautiful full moon, hanging there as if opposing the sun. Naturally, Twilight couldn't make heads nor tails of this situation, only that she knew she shouldn't be here. So, shaking her head, she moved onwards, heading on towards that same hill.
"This isn't real...this can't be real."
She just kept on saying that to herself, as if trying to convince herself that it was true. But her walk was, yet again, interrupted, and only a few metres from the base of the hill. The young unicorn's head turned when, to her surprise, she saw that there was somepony else walking towards the hill. But her expression soon broke out into one of unparalleled joy when she realised who it was.
"Princess Celestia!"
Sure enough, it was indeed the alicorn of the sun who now stood there, staring out across this grassy landscape. But, in spite of Twilight having called out her name, the white mare hadn't seemed to notice, for her gaze was locked onto something else entirely. Confused, Twilight took on a look of confusion.
"P...Princess?"
But again, the Princess did not answer. Instead, her face was one of worry and fear, though of what, Twilight couldn't say. Eventually, the young unicorn turned her head, trying to see what it was that had her mentor so concerned. And like before, her eyes widened with shock. For there was now another alicorn, a black and armoured one, who now walked on the other side of the hill.
"It can't be...Queen Moon?!"
Like with Celestia, the mare of the night did not reply, and simply stood her ground, glaring sternly at Celestia from across the gap that lay between them. For a time, nopony said anything, with Twilight simply looking from one sister to the other. She could feel the tension in the air as this happened, and in the midst of it all, she herself was feeling fear of her own.
"I...I don't understand! What's going on?!"
Again, no answer. But this time, shortly after her outburst, there was, at the very least, movement on the part of the alicorn sisters. They turned their heads in unison, to the hill, and Twilight decided to follow suit. When she looked upon that hill, she started to notice something. At the very top, right where the dividing line between night and day seemed to be, there emerged, from the other side, another figure. From the outline, Twilight deduced that it was a unicorn of some kind, a female from the size most likely. A gust of wind blew, and this mystery mare's mane began to flow as a result, revealing that it was, in fact, quite long. But aside from that, Twilight couldn't make anything out about her. But that thought soon gave way to a more pressing one, as just then, a pair of wings emerged from this mare's back, spreading out regally. Twilight was stunned, taking a step backwards.
"A...another alicorn?!"
As had happened so many times so far, she had little opportunity to properly react to this, as the wind had suddenly kicked up, causing her to raise a hoof to shield her face from it. But as she did this, she looked onwards, seeing this unknown mare atop the hill turn her head, looking over to Celestia. The sun-mare, seeing this, looked back to her with hope, perhaps even warmth. What's more, to Twilight's confusion, the sky seemed to change as a result of this, with the daytime growing larger, forcing back the night. But this moment was short-lived, as the third alicorn then looked over to Queen Moon, who responded with a determined expression, as well as pride, as though having won some great victory. And like before, the sky changed again, this time with the night being dominant. Twilight stood there, in the middle of it all, completely nonplussed.
"What the...?"
This went on for some time, with the third alicorn looking from one sister to the other, with the sky changing between one extreme and the other. But there came a time when this ended, and instead, to Twilight's concern, the mare looked straight at her. Instinctively, Twilight took another step backwards, even more so when, all of a sudden, that unknown pony's eyes opened, and began to glow a bright white. The glow grew more and more, intensifying with every passing moment, until the light seemed to engulf everything around it. Twilight saw it coming for her, and she again raised a hoof to shield herself, waiting for what was coming.
"No...NO!!!"
But, nothing came. There was now no light whatsoever, only darkness, and the sound of her panting furiously. She could feel the sweat pouring down her forehead, and as she slowly lowered her hoof, she saw, to her amazement, that she was sitting upright in her bed. She was home, back in the Golden Oak Library. Squinting, she could barely see anything, and so reached over to her bedside table, wherein she found her glasses. Slipping them over her eyes, she saw that it was just her room, as it always was. No Celestia. No Queen Moon. Nopony. Realising this, Twilight let out a long sigh, raising her hoof to wipe away her sweat. But when she did this, she suddenly felt a sharp pain in her head, like a headache. A very familiar-feeling headache, which lead to realisation in her expression.
"That...that was..."
Her bedroom door burst open, interrupting her train of thought and causing her head to snap in its direction. She saw the worried and fearful faces of Spike and Trixie, with the former in particular now running towards her.
"MOM!!!"
The young dragon rushed to her bed, taking hold of her hoof and looking to her with clear worry. Seeing this, Twilight then took to looking up at Trixie, who likewise started to speak as she entered the room.
"We heard you screaming. Are you okay?"
Twilight relaxed a little, looking back down to her son. He was still worried for her, prompting her to give him a warm and loving smile, as she took her free hoof and gently patted the top of his head.
"Thank you both, but...you don't need to worry."
Spike hesitated, but then spoke again.
"You...you're sure?"
Twilight's smile widened, and she nodded.
"Yes, Spike. It was just a bad dream."
Trixie raised an eyebrow, as though somewhat more sceptical of that claim, and upon seeing this, Twilight looked to her with that same smile.
"Really, I'm fine. Like I said, it was..."
Turning away, Twilight's eyes, just for a moment, had a flicker of doubt.
"...just a dream."
