Sunset was still not entirely comfortable with the internal combustion engine, but she found that the fate of the world helped her get over her issues very quickly. She'd paused only long enough to grab her keys and shoes before jumping into her car and gunning it towards Canterlot High. It was early enough that she was nearly the only person on the road. The only things that stopped her were red lights. She wasn't going to see existence destroyed because she got pulled over.

Once at CHS, Sunset skidded to a halt across three parking spaces, sprang out of her car, and ran across the parking lot, feet pounding against the asphalt. Now she could rush. Now she didn't need to worry about anything but the space between her and the statue.

"Ah, Miss Shimmer! Good morning."

Now she mentally smacked herself. She'd really set herself up for that one. Turning, she said as quickly as she could, "Good morning, Mister..." She trailed off as she took in Mr. Discord.

He grinned, floating a foot above the ground with a familiar creature in tow. "I know, it's a bit much, but what can I say? When I found I could make the law of gravity more of a suggestion, I just couldn't resist indulging myself."

Sunset gulped. Discord unable to resist using his powers. Fantastic. "I see. And Sonata?"

Mr. Discord looked at the siren. "I take it the two of you met recently?"

"She tried to tear my throat out last night," Sunset deadpanned.

"Yes, she does seem to have a habit of doing that, doesn't she?" Mr. Discord considered Sonata. "Or, at least, she did. I must have done something to her, because ever since our little altercation earlier today, she's had all the joie de vivre of a dead slug." He patted Sonata on the side. She just kept staring at nothing. "Probably just worried. Have no fear, Miss Dusk, we'll have you sound in body soon enough. Then we can worry about your mind." He hummed to himself. "Probably a good idea to test that, now that I think about it." He took off his glasses and ran his fingers over his eyelids. When he opened his eyes, there was no sign of the pupils, and the irises were unevenly dilated. He beamed. "Excellent! I can heal!"

Mr. Discord turned back to Sunset, who had managed to cover a bit more distance during his distraction. "So," he said, making her halt and turn back to face him, "aside from an unexpected guest, what did you get up to last night?"

Sunset plastered a grin on her face. "Excuse me?"

"Oh, come now, Miss Shimmer, it's as plain as the horn on your forehead. You've clearly had your own overnight epiphany, one important enough that you didn't even want to waste the time needed to change out of your pajamas." Mr. Discord leaned forward, chin in his hands. "Do tell."

"Well..." Sunset's eyes darted about as she thought. She wasn't sure how Mr. Discord would react to learning how dangerous he really was, and she didn't want to risk finding out. Her frantic gaze noticed something on the horizon. "What is that?"

Mr. Discord scoffed. "Really, now, Sunset—may I call you Sunset? If you don't want to tell me, you just have to say so."

Sunset turned to face the thin purple streak. "No, really, there's something there." She squinted. "And it's coming closer."

Mr. Discord turned to look and stroked his goatee. "Hmm. That is peculiar. Miss Dusk, you're staying here. I'm going to investigate this." He rose further into the sky.

Sunset waited a few moments in case he turned back. He didn't, and so she resumed her race for the portal. She risked a quick glance behind her as she did. Sonata kept hovering where she was. In other circumstances, Sunset might have felt sorry for her, but the siren had tried to conquer the world, which was probably only minutes away from collapse. Sunset's priorities were clear.

Sunset's horn began to tingle as she approached the Wondercolt statue, making her skull shake and her vision blur. By the time she could put a hand on the plinth, every step became a struggle, and not just from the growing headache. The air seemed to thicken the closer she got to the portal. As she rounded the corner, it felt like her head was splitting open as she tried to force her way through memory foam. A trickling dampness on her head made her realize that the first part wasn't a simile, and that the grinding sound she felt through her molars really was bone against growing horn.

The sight of the portal was nearly enough to make Sunset forget her headache. It bulged, a scintillating sky blue curve forcing its way out of the statue's base. "Thaumic flux," she muttered, barely able to hear herself over the growing ringing in her ears. The magic was literally pushing its way into this world.

Sunset worked her way across the statue, going hand over hand. After what felt like an eternity, she managed to plunge a hand into the gateway. A moment later, she felt the prickle of magic grip the limb on the other side, then pull. She yelped as she was yanked back to Equestria.

Mr. Discord hovered above the roof of the school, thinking up experiments as he waited. So much potential, so little time. Just the thought made his brain itch, though some of that might have been the horn buds.

He smiled as the purple streak came close enough to identify. "Ah, Twilight. It appears that this is truly a morning for the history books. Sunset Shimmer also had a pajama-level breakthrough. I trust you're going to be a bit more forthcoming?"

Twilight hovered before him, enclosed in a flowing lavender aura. Her hair whipped about as if in an updraft. She spoke, and her voice was as a chorus. "You are causing a fatal imbalance in the fundamental forces of the universe. Cease."

Mr. Discord threw up his hands. "Oh, come on! Doesn't anyone trust me to manage space and time? They've looked after themselves for this long, how hard could it be?"

The aura brightened around Twilight's fists. "Failure to comply will result in escalation."

Mr. Discord raised an eyebrow. "Wouldn't that be rather counterproductive?"

"The probability of cosmic collapse is greater without direct intervention."

"Hmm." Mr. Discord tented his fingers. "How much greater?"

Twilight glared. "Irrelevant. You have ten to the forty-fourth power temporal quanta to comply."

"You mean Pranck times? So that would be, oh, ten seconds. Which I've mostly taken up by calculating that. And there goes the rest." Mr. Discord gave a laugh. "Well played."

Twilight surged forward, swinging a glowing fist through where his head had been a moment earlier.

Sunset flew through the portal. It took her a moment to realize she had finished the trip; she still felt the bizarre stretching sensation that she associated with moving between worlds. By the time she had blinked her eyes clear, the feeling ended, heralded by the falling hum of deactivating machinery.

"Hi, Sunset," said Twilight, shifting from hoof to hoof, wings fluttering, mane growing more askew even as Sunset watched.

Sunset took stock of her situation. She was held in Twilight's magic, and judging by the decor, they appeared to be in that castle she'd heard so much about. "Hi. Nice pla—"

"No time!" Twilight galloped out of the room, towing Sunset along with her.

Sunset tried to take in the scenery, but something distracted her. "Why are my hindquarters buzzing?"

"That's the Map of Harmony alerting you."

"The what?" asked Sunset.

"Well, I don't know if that's the official name, but it came from the Tree of Harmony, so—" Twilight nearly stumbled as her ramble changed tracks. "Hold on, do you know about the Tree?"

"Yes. Princess Celestia told me everything about the Elements." Sunset sighed. "It's actually part of why I fled Equestria; I figured she'd abandon me as soon as I got Luna back for her."

"Sunset, we can talk about your past regrets as much as you want after we've dealt with the problem that has Discord worried." Twilight skidded to a halt in front of a model of Equestria surrounded by six thrones. Images of their cutie marks floated from their haunches and circled not too far from the model of the Canterhorn.

"Is that the Everfree Forest?" asked Sunset.

"Yup."

"Are we going to need to see the Tree?"

"Most probably."

"Are you going to put me down?"

"When we get there." Twilight resumed her rush until she burst out of the castle.

A mishmash creature was waiting for them. "Sunset Shimmer? I'm Discord." He shook her hoof. "Always a pleasure to meet a fellow member of the Reformed Villain Club." Sunset felt a slight weight press down on her mane. She took it off. It was a baseball cap with a smiley-face sticker roughly placed over a cruel scowl.

"Can you take us to the Tree?" said Twilight.

There was a flash of light, and the three of them stood at the mouth of a cave. Discord grinned. "Signs point to 'Yes.'"

"Great. Thank you!" Twilight galloped in.

"I thought you said you'd put me down when we got there!" Sunset cried.

Twilight came to a stop. "I did." She set Sunset down. "We're here."

Sunset took in the Tree of Harmony. She'd never seen it before, but it felt oddly familiar, like a forgotten memory.

"The Map doesn't tell us what to do, just where to go, so—"

"It's okay," said Sunset. "I know what to do." She walked up to the Tree and put a hoof on the base of its trunk.

The Tree of Harmony glowed. The Elements glittered. Sunset flared with all the colors of her namesake.

Twilight squinted her eyes shut and put her wings over her face. By the time the light died down and she blinked the spots out of her eyes, all that remained of Sunset was a carbon smear in the shape of her cutie mark. Even as Twilight watched, some of the blackened matter sloughed off of the Tree's roots.

Eyes wide, Twilight looked up at the core of the Tree, where the Element of Magic still gave off a faint glow. "I really hope you know what you're doing." She wasn't sure who she was talking to, but she meant it.

Author's Notes:

When every second counts, even the narration doesn't have much time to spare.

As for why Twilight didn't teleport, she's panicking, and with good reason. When adrenaline shouts "RUN!" in your ear, it can drown out the quieter voice saying "Or fold space." Plus, teleporting into the Everfree still isn't the best of ideas for anyone other than Discord.