“Not a sign of her?” Spike looked hopeful.
“I’m afraid not, darling. I thought she mentioned something about helping you, Applejack?”
Applejack nodded. “She was supposed to, but she never showed up. It wasn’t too big a deal, and I figured she was running late for a good reason. I imagine she’d show up sooner or later.”
Rarity ‘hmm’d’ softly. “Have you checked dear Fluttershy’s place?”
Pinkie piped up. “Yeah. She’s not been there, and nobody else has seen her since yesterday.”
Applejack gulped softly before speaking up. “Spike? At this point, I’d say we should get the Princesses involved if she’s really vanished like this.”
Spike nodded and opened his mouth–
Only to be interrupted by Rarity. “Spikey? Do you need paper and a quill?”
He nodded again. A moment later and he had both.
Celestia,
We can’t find Twilight. She was supposed to meet Applejack this morning and nopony has seen her since last night. We’re worried something happened to her.
Spike, Rarity, Applejack, and Pinkie Pie
He rolled up the parchment. “Alright now that’s– hrrk!”
He burped up a scroll with Celestia’s seal. His own scroll forgotten, he unravelled the one he received and read it aloud. “Twilight,
Luna passed over Ponyville last night on her nightly patrols and had a ‘feeling’ of something bad coming from Ponyville approximately two hours before dawn. Has anything happened in town? Are you alright?
Concernedly,
Celestia and Luna
P.S. She blew in my balcony. Again.”
Once he finished, Spike dropped the letter before tearing his own back open. He quickly scrawled a second note on the back.
Celestia and Luna,
Twilight is missing. Nopony has seen her since last night. These two things have to be related. Could one or both of you come here ASAP?
Spike, Rarity, Applejack, and Pinkie Pie
He immediately sealed it and sent it on its way.
“There, I sent it.” Celestia’s left wing wrapped around Luna’s body gently. “Alright?”
“Alright, Tia.” Her ears folded back as she leaned into her sister’s hug. “I’m still sorry for destroying your balcony and spooking the guards again.”
Now in a considerably better mood, she nuzzled Luna’s cheek. “I forgive you. It is definitely something to get Twilight’s attention about. I just hope she replies soon.”
Luna’s mouth opened as a green puff of smoke coalesced into a scroll at the tip of Celestia's horn.
Luna smiled softly. “That was fast.”
“See? Probably nothing to worry about.”
Celestia unrolled the scroll and read it once, twice, three times. Luna didn’t want to intrude on a letter from Twilight.
“Sister?”
All emotion had fled Celestia’s voice. “Twilight is missing. Has been since last night.”
Luna dipped into the Royal Canterlot Voice. “What!?”
Turning the letter over, Celestia spotted the letter Spike had written originally. “They were just about to send this to us.”
“Do we… what do we do, Tia?”
“I…”
Luna took the letter and read it, both sides. Not looking up from the letter, jabbed Celestia’s chest. “Go.”
“Lu…”
“Celestia. Go. I will hold down the castle!”
“Lu…”
Lifting Celestia in her magic, she hurtled Celestia out of the unrepaired balcony, arcing almost directly toward Ponyville. Stepping out to make sure Celestia kept going, she shouted “Go, Celestia! I will be fine here!”
Shocked into motion as she soared down the side of Mount Canterhorn, her wings slipped open and carried her into a glide. As her sister’s shout hit her, Celestia clenched her eyes shut, tears in the corners spilling down. She reached deep into her magic pool and teleported to Ponyville.
Barely a minute later, a boom sounded above town. Spike shot up and right out the door, looking skyward, seeing Celestia drop down from a glide to land outside the Crystal Castle.
“Princess Celestia!” He called out
“Spike? Spike!” Her horn lit and he was suddenly crushed against her chest inside the castle. “What happened?”
“I don’t know. Twilight didn’t wake me up this morning and we can’t find her. She vanished.” Spike’s tears soaked into Celestia’s chest, and he hiccuped softly.
“What was she working on yesterday?” Shushing him softly, she did her best to comfort him, even as she cried herself.
“Just her normal projects. She was nearly done with a new… spell…” Spike’s eyes widened as he remembered the spell scroll he saw earlier.
Celestia stood, a hoof holding Spike to her. “Where is it?”
“Her desk. Come on, I know the way.” Struggling free, he sprinted off toward Twilight’s room.
Minutes later, he stopped outside a door, panting. “Here’s… here’s her room. There’s a scroll on her desk that I didn’t recognize, other than it was definitely her work.”
“Alright. Spike, gather the rest of Twilight’s friends. I don’t know if we’ll need their help, but I will try to figure this out.”
He turned around, but before he started away, he ran back and grabbed her hoof. “Promise… promise you won’t cast it without supervision, alright? We don’t need to have to find you, too.”
Celestia nodded. “I promise. We will find her. I swear on my crown.”
Spike nodded and sprinted off again.
“Now, what have you created this time, Twilight?”
Making her way to the messy desk, she didn’t dare touch anything, merely looking over the scrolls, notes, and books seemingly scattered across it.
Taking note of everything’s order, Celestia scanned the rest of the office. Seeing Twilight’s calendar, she spotted something troubling. The mark for a complete spell was right around the time Luna mentioned her feeling.
“What have you done, Twilight…”
She found the scroll on the floor where Spike had left it. Years of tutoring Twilight left her at an advantage in decrypting Twilight's spells. It was flawless. A reusable time travel spell. Built in failsafes that should send the user back to their timelines, ways to prevent paradoxes, even accidentally. Only an alicorn could cast this spell from the scroll. Any other casters would require setting up a spell circle and ritually casting this, one individual spell at a time.
She was an alicorn. She had plenty of magical power. She could… 'I can cast this. I can save Twilight.'
Drawing from the power of the sun, she refilled her magical reserves.
“Princess?”
Looking up, she saw Spike with the rest of Twilight’s friends. “I’m glad you all came. It seems Twilight has cast some new spell she finished last night.”
Rainbow shot over to Twilight’s desk, trying to read over Celestia’s shoulder. “What does it do?”
Celestia’s magic encompassed the entire table as Dash’s wake threatened to disrupt Twilight’s setup. “It’s supposed to be a reusable time travelling spell.”
Pinkie tilted her head cutely. “Really?”
Celestia nodded. “Yes. She’s built a great spell here. It should return the caster to the same point they cast it if it fails, or if any other conditions are met.”
Applejack sat down next to Spike. “Like what?”
“The caster is injured, causes injury to others, or causes a self-referential paradox, to name a few.” She looked over the desk. “Spike? What spell is she basing this off of? I don’t think this is an entirely new spell.”
“I think she based it on the scroll she used to go back in time a number of years ago. The time we ended up in the library a week later?”
Celestia called that scroll up from her memory. ‘Star Swirl’s one-use time travel spell. Any caster can only go forward or back with it once.’ “Does she have a copy? I want to compare it to that.”
“I think she does. It’s probably on the desk here somewhere.”
Celestia slowly separated the items on Twilight’s desk until she found it. Setting the two side by side, she saw the difference almost immediately.
“How… how could she miss this?” Of all the failsafes that Twilight had built in… Celestia’s wings opened in an instant and tossed Dash toward the ceiling. “She forgot that?” Her mane and tail started to flow faster and faster, the individual colors blending together into an almost sunset-orange.
“Um. Princess? What did she forget?”
Shaken, Celestia calmed down, and her mane and tail returned to normal. “She forgot to account for Equus’ position in the solar neighborhood.”
Pinkie gasped like it was the worst thing. “Oh no!” Two seconds passed. “What does that mean?”
Rarity piped up. “She forgot to account for how the planet drifts and moves over time?”
“How did you…”
Swishing her hair playfully, Rarity replied cheerfully. “Sweetie Belle had a fascination with celestial phenomena a year ago. Stargazing and watching comets and meteors. Somepony had to teach her.”
Dash settled down on top of one of the nearby bookcases. “Um, doesn’t the sun revolve around Equus?”
Celestia nodded. “Yes. That doesn’t mean it isn’t physically moving in the solar neighborhood.”
“So that means…”
“When Twilight cast this spell, she went forward or back in time. Without moving physically along with the planet as it travelled in time.”
“So, all we have to do is go after her? Easy peasy. Fire it up, Princess! Let’s go get her back.”
“Unfortunately, it’s not that easy. If I cast the spell now, we don’t know when she went. We have one shot to get her back.” Celestia brought the calendar up. “Twilight wrote the date and time when she completed the spell.”
“Mhmm.”
“So, I have to cast the spell correctly, accounting for that, to see where she goes, and follow her with,” she lifts the bad spell, “this spell, and rescue her. Then come back here.”
“Why back here?”
Rarity chimed in, following the magic discussion easily. “Paradox, remember? We’ll have to come back to a time just after I leave.”
Applejack nodded. “Right.”
Celestia swept her gaze over all the other ponies in the room. “So, I only get one chance. No. We only get one chance. In addition, only an alicorn can cast this spell unaided. The sheer power required is too much for any regular unicorn to attempt. I will need to cast it four times.”
Dash seemed to deflate a little. “Oh. Yeah, that’s a whole lot more complicated than I thought.”
“Now, Miss Rarity, would you mind helping me rewrite a correct spell? Do you happen to have the–”
A calculation for planetary drift slowly slid up to float next to the spell. “Here you go. I knew what was coming.”
“Thank you, Miss Rarity. Now, I’m afraid I’ll have to ask you all to step out. I don’t want to disrupt this casting, please.”
Dash took off quietly and zipped out of the room, followed by the others. Spike lingered for a few seconds. “Please, save her.”
Celestia nodded. “I will. I swear it.”