Author's Note
This is an unofficial sequel to LordBrony2040's "Sunset Reset" As such, it is not canon to his story, just a possible alternate timeline. My thanks to LordBrony for allowing me to play in his pool.
I'm a huge fan of Sunset Reset, and I wouldn't dare assume I was worthy of continuing on it, but it DID give me some ideas that begged for expression, so here we are.
Prologue
Princess "Mi Amore" Cadenza, otherwise known as Cadance (or Princess Cadance at most) to her friends, was starting to get worried. Every night for a week, Sunset Shimmer had slipped out of the Alicorn sized bed she and Cadance shared with their coltfriend, Shining Armor, after Shining had drifted off to sleep and then had been missing for nearly an hour before slipping back into bed.
It wasn't as if Cadance wasn't used to Sunset putting in some late night work, either drawing up new legislation or working on some new invention, usually inspired by her time on the world of humans she'd spent nearly three years living in while in self-imposed exile from Equestria, but USUALLY Sunset would stay in their apartments, the faint light from her horn and the rustling of books and papers, quill and ink being something that had started to become almost relaxing to the Alicorn of Love.
But whatever Sunset was up to this week, she didn't want anypony else to know about. Cadance had tried to follow her, but Sunset had apparently been teleporting away from just outside their room, and Cadance didn't have the skill to track a teleport, even though she knew, from what Celestia and Sunset both said, that it was possible.
She could go to Celestia, of course. While the eldest Alicorn in Equestria certainly had the skill to track down her adopted daughter, Cadance didn't want any reason to cause any more issues between the two hot-headed solar alicorns. Things between Celestia and Sunset had been intense ever since Sunset had returned to Equestria as a full-fledged alicorn... one more powerful than Celestia herself by a significant margin. Not that 'returned' quite fit the unusual circumstances of her ascension. One moment, Sunset Shimmer was looking into Starswirl's mirror portal, the next, with a flash of light, she'd apparently transformed into an Alicorn.
The truth was somewhat more complicated. Cadance felt her head hurt just thinking about it. Somehow, Sunset had traveled back in time to a month before she'd left through the portal in the first place, making the events that would cause her to flee through the portal in the first place never happen. The only pony who could remember the events of that alternate timeline were Sunset herself. Not that Cadance doubted Sunset's explanation. Not anymore. Too much evidence had piled up to show that everything really had happened the way Sunset remembered it. It wasn't Sunset's recollection of events that Cadance doubted, it was her interpretation of the reasons behind them... and of the motivations of Sunset's "best friend" in that alternate timeline. Princess Twilight Sparkle.
In the end, while gravely tempted to pass through the portal back to the human world in an effort to try and set things up so that her presence in their world wouldn't prevent Twilight Sparkle from becoming an Alicorn and a princess, Sunset Shimmer had agreed to stay. She'd become such a huge part of so many ponies lives and Cadance had managed to persuade her not to leave, arguing that her leaving would cause more harm than her staying.
Cadance herself was incredibly happy that Sunset had chosen to stay, not in the least because that meant that the mare that she had fallen so madly in love with wouldn't leave her. She, Sunset, and Shining Armor had somehow stumbled into a three-way relationship that was, as far as Cadance knew, unique in Equestrian society. They were partners... each to the other. Cadance loved Shining Armor AND Sunset, who loved Sunset and her, who loved her and Shining. They each had their own unique relationship with each other, but, with work and care, they managed to balance their odd relationship into something that Cadance found incredibly fulfilling and rewarding.
But being in love didn't solve everything, especially not for a mare as complicated as Sunset Shimmer. Sunset still carried a great deal of guilt over her supposed crimes of the past... over the wrongs she had committed before learning, as she put it, about the 'magic of friendship', and she still had huge issues with self-doubt and self-loathing. She found it incredibly difficult to believe that she deserved to be happy, and Cadance made a point of ensuring that Sunset knew that she was loved and valued every single day.
Whatever Sunset Shimmer was working on, she didn't want anypony else to know about, and that worried her. It wasn't that Cadance didn't trust Sunset. She knew implicitly that Sunset would never deliberately harm her, Shining, or anyone she cared about, but that didn't mean Sunset wasn't capable of harming them indirectly by a misguided desire to punish herself... or to try and "fix" something that shouldn't be repaired. If Sunset Shimmer insisted on hiding her actions, there wasn't much Cadance could do to stop her, but that didn't mean she shouldn't try.
Slipping out of bed herself, careful not to wake Shining Armor, Cadance went to the entry hall to their room to wait for the love of both their lives. If she was right, Sunset wouldn't be very long. Opening a book on Crystal Magic that she'd been studying for the past few weeks, Cadance settled down to wait.
*********************
It seemed longer, but a glance at the clock told her that it had been just a little bit more than an hour when Sunset slipped quietly through the door from the Castle hallway outside into their entry hall, obviously intending to head back to bed.
"What's going on, Sunset?" Cadance asked quietly. "You've been sneaking out every night for a week now. What are you working on that you don't want to talk to us about?"
Sunset started slightly at Cadance's voice, and her slightly wide eyed look told the pink Alicorn that she hadn't noticed Cadance waiting for her. "Working on? Er..." Sunset's eyes shifted up and to the right, and Cadance sighed.
Cadance frowned. "Please don't think up an excuse. If you don't want to tell me, you don't have to, but don't come up with a lie. You owe me better than that."
Sunset sighed and hung her head. "I know... I just. I don't think you'd really approve of what I've been doing."
Cadance raised an eyebrow. "That doesn't sound good. But you know you can't just leave it at that. I'll worry more if I have to guess."
Sunset took a deep breath and nodded. "Yeah. I know. It's not like I'm doing anything bad or anything. It's just I know you don't like the idea of me messing around with the Mirror Portal."
Cadance's eyes went wide. "You're right about that! Sunset! What are you thinking? You can't possibly intend to go back to the human world, not after everything..."
Sunset quickly shook her head. "No! No... I know that I nearly did that before, and I'm sorry about that. I know I can't put everything back to the way it was, and I really don't want to leave you and Shining... and mom, and Twilight and the girls. And I know that if I left it'd hurt all of you. So no, I'm not planning on going anywhere."
Cadance looked confused. "So why? What good does messing with that mirror going to do you?"
Sunset shrugged. "Well, I started thinking about how to fix the main thing I've been worried about ever since I came back. That going back in time and becoming an Alicorn, I may have jeopardized Twilight Sparkle's chance to become an Alicorn... and a Princess. I know I'm already planning on helping her as much as I can, but how do I know it'll be enough? Becoming an alicorn isn't as simple as I used to think. Mom can't just poof wings on ponies who she thinks deserve it. It isn't about magical aptitude, or, no offense, you'd never have become one."
Cadance laughed. "None taken. I know I'm not the magical prodigy you or Twilight are."
Sunset smiled. "And it can't just be about being a wonderful pony... or I wouldn't be one either."
Cadance frowned at her lover and nearly growled. "You ARE a wonderful pony, Sunset. Although I think you're right. If you have to be some perfect, kind and caring, infallible wonder pony, Celestia certainly would never be one."
It was Sunset's turn to glare at the smaller alicorn, who bore the Amber alicorn's ire with aplomb. "Mom may not be perfect, but nopony is... and mom has done things nopony else could have managed. Holding Equestria together for a thousand years...."
Cadance held up a hoof. "Nopony is saying Princess Celestia hasn't been a fantastic ruler for a millennia. And It'd be hard to find a pony who cares about her subjects more. But she's nowhere near perfect."
Sunset rolled her eyes, then nodded. "Right... so becoming an Alicorn isn't as simple as being powerful, or skilled, or even just being a good pony. There's something more to it. I want to make sure that I can guide Twilight down the right path to her destiny. I KNOW she'll be a wonderful alicorn someday."
Cadance looked confused at that. "OK, that part I understand, but what does that have to do with the mirror? Do you plan on having her look in it, so she can see her destiny? I mean, we know how well it worked out for you..." Cadance trailed off. "Well, I guess in the end it worked out pretty well. I mean, you saw yourself becoming an Alicorn in the mirror, and eventually that's exactly what happened. From our perspective, you became the alicorn you saw the instant you looked in the mirror, even if you had to take the long way round on your own."
Sunset frowned. "Well, I thought about that... I don't think mom would be thrilled about having Twilight look into the mirror like that after what happened to me, but I figure I could probably convince her it was worth it. But no, that wasn't what I had in mind. I've been doing some research on Star Swirl's work in temporal and dimensional mechanics, and I've think I've almost got it worked out."
Cadance blinked. "Got what worked out?"
Sunset grinned. "How to talk to Princess Twilight Sparkle herself, that's what!"
