Sunset Shimmer was a wiser mare.
In terms of subjective time, she had spent decades, years spent cramped in identical benches in identical classrooms, with the same handful of teachers. She had discovered on her second class that the teachers weren't smart enough to tell if she was paying attention to them, and they'd never move on until she responded to their questions and took their tests.
Thus, with a few mental tricks she'd learned from Celestia, Sunset could ignore the mental compulsion trying to force her to study, and direct her mind elsewhere. Once she was started on some other task, her brain would happily latch onto that instead, and couldn't tell the difference between it and whatever the teachers wanted her to learn. At first, she used this "extra" time to practice some of the basic concepts being taught to her, going over them in more detailed ways, combining them with things she'd learned in previous lessons. But another few classes later, and Sunset used the compressed time for purposes entirely disconnected from her classes. Everything the pocket reality did to suppress physical needs and claustrophobia was still in effect, so she never got anxious. Sunset Shimmer had done what Celestia herself had never done, what even Star Swirl hadn't done: she'd mastered time.
What did Sunset Shimmer do with all her extra time? Experiment, at first. Datamancy was a complex magic, revolving around the central reality that the entire world was nothing more than an immensely powerful series of calculations performed by a computer called the Infinity Engine. It could be expanded with an infinite number of modules, hence the name. Every module was another shard, a simulation of the world perhaps the size of a city, with its own rules, constraints, and flow of time.
Contrary to what the thief Jackie had believed, this revelation was itself no great shock to her. Sunset's understanding of the magical framework of the physical universe did not illustrate anything fundamentally different: Equestria too had a Kernel, which defined the thaumaturgical behavior of all matter on Equestria. Sunset had even visited that Kernel in the company of her then master, possible only after a difficult journey through the Everfree and much hardship. Learning that the builders used a similar trick, albeit with a different school of magic, was not a big deal.
If anything, it meant she saw datamancy more completely than even the instructors (or the ones who had designed them) possibly could. The material she read in every new class was full of reassurances and comforts for Builder students, reminding them of meaningless philosophical fluff about "the significance of a human life is measured by its experiences, not the context which created them." As if she needed reminding.
By her third class in the series about datamancy, Sunset found the exploit she needed to shut the instructor down, and let her work in peace. By her sixth, she found the weakness in the completion authentication subroutine that would allow her to bypass the order of instruction entirely. There was no more need to waste time with fields like "chemistry" and "ethics," and she could focus all her attention on her plan.
Sunset was not actually any older when she first put Jackie's words to the test, though decades of practice and study had passed. So far as Sunset's brain knew it, she'd been a human living in this school for longer than she'd been Celestia's personal student. She almost couldn't remember what it was like to stand on four legs, or the taste of a good hayburger. She would have to fix that.
So, she made her way into the school's cafeteria, shoving right through any of the simulated students who got in her way. It didn't matter how inconsiderate she was to the population of simulated low-level atmospheric processes, it wasn't like there was a real mind behind them. Not yet, anyway.
Plenty of students were congregating in the lunchroom, with plates of food looking as fresh as though they'd just come out of the kitchen. Every single plate was as perfect as she was, untouched by time. Only when she looked at them did any of the students take a bite, and even then, the amount of food on their plates wasn't going down. I see through all of you, Sunset thought. But not for much longer.
Sunset had learned terrible things in her only class about human history, but many of those things had also been useful. She'd learned, for instance, that the module currently running this school was one of the largest in all the Infinite Realm. It had been built at a time of wartime desperation, when hundreds of thousands of people had used it at any one time. It had been left intact into modern day, in the hopes that one day citizens of the Federation would wake up and flock to it anew. Of course, there was only one mind inside it now. One mind using resources meant for hundreds of thousands, with almost no restrictions.
Sunset scanned the lunchroom, searching for a suitable candidate for her experiments. She found one towards the back, a girl with bright purple hair and a pair of thick black glasses. She was eating alone surrounded by a mountain of books, though she seemed to be doing far more studying than eating. She didn't look even one bit like Princess Celestia's newer, smarter, more obedient, friendlier apprentice. Not even a little bit.
"Hello, Twilight," Sunset said, as she sat down on the other side of the plastic bench across from her. She shoved with one arm, sending a dozen books careening to the floor at their feet.
The girl looked up, impotent anger on her face, and she opened her mouth to object. "Excuse me," she said, and the emotions seemed almost real. "What are you doing?"
"Finding a use for you," Sunset answered, one hand on her GIO. The device was now as thin and sleek as Jackie's, though it had Sunset's cutie mark etched into the plastic, as well as an orange and red color scheme. It also had voice commands. "Suspend execution of slave process." The girl who was certainly not Twilight Sparkle froze, her mouth still hanging open. None of the other students seemed to notice, nor had they reacted to Sunset's intrusion in any way.
Sunset waved one hand in front of the girl's face, but she didn't even blink. She wasn't all that different from the teachers, really. Just a bit of scenery with a few pre-programmed reactions. But why does she look afraid?
This was as far as she'd ever gotten with the instructors—she had always suspected that damaging them might attract a system administrator, and so she'd never done anything more than suspend them. She scanned over the code for the function she'd written, one that would be required for her plan to have any hope of success. No reason the administrators would be watching what I do to the scenery. These weren't people. It was okay, she wasn't doing dark magic. I'm not going to invite the abyss into my mind because I trim the bushes. Changing the background people is the same.
Sunset believed that, but it took her nearly a full minute to say the keywords that would activate the spell. "Edit mode," she said, gesturing at the figure in front of her.
"Subroutine edit mode activated," the girl responded, her voice now flat and emotionless. That was part of the spell, the part that let Sunset know she had succeeded. She began fiddling with her GIO, dragging her fingers across and transferring a few of the most important programs she'd written. This girl wasn't just her first test subject, she was also about to become an important node in the process of taking over this shard. Every class Sunset had taken (and she'd taken almost all the classes on Datamancy now) emphasized the dangers of permanent modifications to her own mind. As Jackie had put it, Sunset lacked any canonical backups. If she made some mistake that melted her brains, that would be it. This was as dangerous as a unicorn's first teleport, and so it required the same level of care. Unicorns practiced with inanimate objects, then plants, then animals. Sunset could do the same.
The girl twitched slightly in her seat, one hand reaching up to the side of her head. She looked like she was about to pull away, maybe to run. It wouldn't have helped if she did—Sunset's GIO wouldn't care about range. Sunset winced, her heart thumping in her chest as she stared at the projection. How in Celestia's name had it moved while she was working on it? Probably just a bug in one of my programs. I accidentally bridged something I shouldn't, that's all. "Do not get up," Sunset instructed, her voice firm, meeting the girl's eyes. "You will not rise until I say so."
"Command acknowledged." She put her arm down, slumping back into a motionless position. She remained there for the remainder of the transfer, no longer struggling in any visible way. Only her pained expression remained, her mouth slightly open and a little drool dribbling down her face.
It didn't take all that long, less than a minute really. Her GIO made a high-pitched ringing sound, indicating that the transfer was complete. Sunset began to smile. "Self-diagnostic," she said.
The girl rose at once, knocking over her food and walking out from behind the bench with no regard for the books Sunset had scattered on the floor all around them. She practiced walking back and forth, moving her arms in various ways, all the while Sunset's GIO felt warm against her skin as it filled with the internal processes this first node in her network was undergoing. This process amounted to a stress test, meant to determine if the administrators governing this shard had anything in place to notice when a piece of the background scenery suddenly demanded the same kind of resources as a real mind.
Another minute later and she stopped moving, turning back to face Sunset. She didn't stand rigidly anymore, not even like a solider. She rested in a natural standing position, indistinguishable from any human. I didn't write that animation. I wonder if the original program is still in there somewhere. It didn't matter really, so long as the program could still do what Sunset wanted it to. "Computation Node 001 registers as functional, administrator. Requesting functional designation and first assignment."
"Your designation is... Twilight Sparkle," Sunset said, while one of her hands danced over her GIO again. The projection didn't even seem to notice as Sunset adjusted a few physical details on the girl, making her a little taller, a little slimmer, changing her eye color, switching her hair... all these were details any citizen could change about themselves in many shards, though it was supposed to be fixed in this one. Fortunately for Sunset, Node 001 wasn't a citizen. I can't wait to see your smug face when I show you my Twilight is smarter than yours.
"Designation Twilight Sparkle accepted," she said. "Please input first assignment."
"You're going to be my assistant, Twilight." Sunset rose from the table, dislodging a few more books in the process. "As of this moment, I'm a princess."
Twilight no longer looked like she was in pain, or like she was going to run away. Rather, she seemed like one of Celestia's own servants, eager for a command. Eager to make herself useful.
Don't you worry, Twilight. You're about to become the most useful bit of set dressing in pony history.
"Assignment accepted—personal assistant. What is on our agenda for today, Princess?" She removed a pad of paper and a pencil from the table, ignoring all her other objects. "I will do everything within my ability to ensure you are free to concentrate on more important matters."
"Good." Sunset turned away from her, facing the room. There were at least a hundred Builders in this room alone. Assuming every instance of the school had the same population this one did, there were thousands and thousands of subroutines to rewrite. "Your first assignment: I need local time compression at a factor of 120 to 1. Please pay for it using your own process resources."
There was a lurch, and the room around her went abruptly silent. No one ate, no one spoke, or moved their tableware. It was like looking at a photograph.
Except for "Twilight," who walked over to stand beside her. "Command accepted, Princess. Local time compression enabled."
Sunset felt a wide grin spread involuntarily across her face. "Let's get started."