Magic
She'd finally done it!
she'd finally gained enough power to teleport from the moon to the planet below. It had just taken her a little longer than she'd thought it would have. 10 years to be precise.
Not much had changed about the purple unicorn in appearance. She was still a magenta mare, albeit a bit more dusty thanks to all that time on the moon. Yet even Twilight had to admit that she hadn't given herself a proper once-over in, well, a decade. But she didn't have time to dwell on her appearance. She had to get back to Ponyville and seek out her friends to explain everything. She hadn't been able to shake the nagging doubt that something had happened to Luna to prevent her from delivering the message to her friends full stop. And she waited until the opportune moment, the moment when she could time her teleport so perfectly that she would land back in her old library. She saw her goal... and. BOOM.
To a casual observer, looking up from the town of Ponyville, they would have seen a glowing sphere of. Something. Appearing on the surface of the moon, and exploding, creating a small crater in the moon. But of course, nopony looked up, nopony ever looked up any-more...
She landed in the library with nothing more than a small thud, yet Twilight was experiencing the worst migraine she'd ever felt. Her head felt like it was on fire, and she could hardly open her eyes without letting out a strained grunt as the harsh sunlight beamed down into them. Wait, Sunlight?
Twilight sat up violently, and cringed, as the action set off another set of pain receptors that Twilight didn't even know she had. But she still steadied herself, and fought to get her body back under her control.
She looked around, at her surroundings. She was in her library. That was true.
What was also true was that there were no more books in the library, and there was an inch thick layer of dust on the bookshelves. Yet even through all of this mess, Twilight could tell that it was still her library, even though her memories were faded. She knew her own organised chaos anywhere. The remnants of said chaos were still on the desk, and scattered around the floor.
As she looked around, she started to see that this was no-longer a place of reading and study.
It had become a museum, an artefact, hidden and locked away behind the faded door, and boarded up windows.
She was hard pressed to say that she'd once lived in here. But still, nothing that a little magic couldn't fix. Soon, the room was glowing a brilliant purple as all the dust disappeared into the void, and everything was tidied up.
And yet.
An empty library by any-pony's standards is an empty library.
Useless.
Twilight decided to look around the old tree, checking the basement first, and finding all of her previous experiments gone. Just gone, no note, not a single piece of equipment left behind. Everything had been taken. She couldn't really blame them though. She had been gone for 10 years, in fact, someone else may have lived there, and decided that they didn't like the basement decorum. See, an explanation that fits.
Well, apart from the obvious disuse that the place has suffered.
Her next stop was her bedroom as she decided that the best thing for her at the moment was a long sleep. She couldn't remember the last time she'd slept, or eaten for that matter. Immortality had that effect on a pony she assumed. She opened the door to her bedroom, and all thoughts of sleep were banished from her mind.
On the bed, there was a small purple and green shape.
It wasn't moving.
It would never move.
She was back, and she was oh, so alone.