“Okay so explain this to me again,” Lightning Dust said. She held up a hoof. “This time without using really long words.”

Doctor Sparkle gave her an annoyed look. “Stop moving around so much. Adjusting this new armor is difficult enough while you’re standing still, much less when you're wiggling like a bored foal.”

“I just wanna know what’s happening so when it explodes and kills me I know what to scream while I’m on fire.” Dust put her hoof down and tried to stay still, wincing as a strap was pulled tight. The new suit was sleeker than her usual armor, but managed to make up for it by being heavier and having a bunch of odd protrusions.

“Do you remember the antimagic field? You were able to use a suit with a battery,” Sparkle said. “It still worked even with your own magic cut off.”

“Right.”

“This suit is a prototype designed with integrated batteries. They’ll recharge from your Engine Heart over time. But when you need it, you’ll be able to activate them and reverse the flow to force mana into your leylines.”

“So what? If we run into another dead magic zone I’ll be able to keep going for a while?”

“It was an anti-magic field, it’s totally different--” Sparkle sighed. “Yes. It would let you keep going.”

“That seems kind of like a limited application.”

“It would be, if it was the only point of the system. By temporarily increasing the density of your thaumatic particle field…” Sparkle stopped, watching Dust’s eyes glaze over. She sighed and tried again. “It will work as a power booster for a limited time.”

“And you got a new suit of armor together already? What, did you have the parts just lying around?”

“I’ve been planning this for some time as an, ah…” Sparkle thought for a moment, then the word came to her. “An incremental upgrade, let’s say. When I had you on the table after your cardiac arrest we adjusted your Engine Heart to handle the flow reversal. Now that the armor is finished we can test the system.”

“Neat. So it won’t work for Sunset? Won’t she be upset?”

“Once we’ve proven the practical application I’ll be happy to work on an upgrade for her as well,” Doctor Sparkle said. “You’re the best test subject, though. Without Earth Pony magic Sunset is too fragile in case something goes wrong, and Marble has stability issues.” Sparkle paused. “With her Engine Heart, among other things.”

“Sure, that’s one way to put it,” Dust snorted. Sunburst lowered a helmet over her head.

“Let’s do some pressurization tests,” Sparkle said. “Better to blow a seal here than at sixty thousand feet.”

“Your Highness, we have the field report you requested.” Ensign Alias had knocked three times before coming in. Almost everypony who had served under Princess Cadance had learned to knock first just in case there was somepony -- usually Shining Armor -- serving under her in the immediate sense.

Thankfully Cadance’s dignity wasn’t at risk with what she was doing now. Well, unless seeing her drinking coffee caused some kind of moral shock among the tea hardliners. She never could resist a pumpkin spice latte, though.

“Thank you, Ensign,” Cadance said, taking the report in her magic.

"It's never a problem, Ma'am. You're a pleasure to serve."

Sunset Shimmer sat across from Cadance, wearing her white armor. Bronze wings fluttered at her side quite naturally, as if she’d always had them. The Ensign smiled at her. Sunset couldn't tell if it was smug or genuine.

“Is there anything else I can get you, Ma'am?" Alias asked. "You haven't had lunch yet."

"Oh, that would be lovely, thank you," Cadance smiled. "Bring something for Sunset as well."

"Of course, Ma'am." The Ensign saluted and left, quietly closing the door behind her.

“What’s in the report?” Sunset asked, after the pony left.

“Celestia started a new counter-offensive,” Cadance said, opening the folder. “I thought you should know.”

Sunset had known already, of course. Doctor Sparkle's sources had gotten their hooves on the plans already. “Is it going well?”

“Sombra is having supply line issues, and they’ve broken through almost all the way to the Empire’s front doorstep.” Cadance smiled. “The war might actually be over soon. I just wish we didn’t have to…”

“She’s making progress because she’s finally started using lethal force on the conscripts,” Sunset said. It wasn’t a guess. She’d seen the papers. “It took her long enough.”

“I don’t know the details, but they say it’s better in the long run.”

Sunset had seen the numbers. EIS projected that using lethal force now would result in less than fifteen percent of the total casualties involved in a longer, drawn-out war. The difference was that it was all at once, and the blood was on Equestrian hooves instead of Sombra’s.

She shrugged. There was no point getting into an argument with Cadance about the methods when she was getting a free lunch just by being pleasant.

“It’ll be good for things to get back to normal,” Sunset said. “Maybe Celestia will be easier to deal with if she’s not so stressed out.”

Cadance smiled. “It’s always worst when two people that care about each other start fighting. Everything is personal and things get blown out of proportion… but I know part of her still loves you.”

Sunset raised an eyebrow.

“I’m serious. I’m the expert, you know. If you want a second opinion you’ll need to dig up another pony that can sense love.”

Ensign Alias knocked on the door, bringing in their lunch.

“Sixty thousand feet,” Sunburst reported. “Altitude holding steady.”

“How does the suit feel?” Doctor Sparkle asked. At this distance, the crystal radio spat and crackled with the amplification needed to push a signal through. She watched Dust on the monitor, the scrying spells showing her as little more than a glowing dot.

“Not bad,” Dust said, her breathing heavy when she spoke. “A little harder to get lift with the air this thin, but I feel like I could go a million miles an hour.”

“Just keep it under control. When you’re comfortable, we’ll activate the booster system.”

"Do we have a name for it yet?"

"Not really. I've just been calling it a battery booster."

“It needs a cooler name than that.”

Sparkle sighed. “You can name it when you get back.”

“Yes! Thank you! That’s the smartest decision you’ve made today.”

“Whatever she comes up with, don’t put it in the official report,” Sparkle noted, whispering to Sunburst. He nodded in agreement.

“The radio is still live,” Dust said. “I can hear you.”

“Activate the battery booster,” Sparkle ordered. “At maximum power you’ll get five minutes. Shut it down immediately if the readings fall outside the safe zone. I'm worried about the heat it might generate. We haven't properly tested all the components.”

“I remember the briefing,” Dust sighed. “I’m a professional.”

“Activating booster,” Sparkle said, pressing a big red button. She watched as the thaumatic readings shot up, like fuel thrown on a fire.

“She’s starting to accelerate,” Sunburst noted.

“Try to keep your pace down, Lightning Dust,” Doctor Sparkle said.

“Yeah, yeah,” Dust said.

"How's the heat output?" Sparkle asked.

“It's barely within tolerance. But she's still accelerating,” Sunburst said. “Lightning Dust, you need to slow down and turn around. You’re going to leave radio range.”

“I’m trying to!” Lightning Dust’s voice had an edge of panic. “I can’t stop!”

“Shut down the booster,” Sparkle ordered. Sunburst hit a safety switch. Nothing happened. He hit it again. Sparkle shoved him out of the way and hit it herself just in case her lab assistant couldn't press a button correctly. She didn't have a lot of faith in other ponies.

“I could use some help here, Doc!” Dust screamed.

“She’s almost out of detection range!” Sunburst said. Sparkle glanced up at the display, then pried the control panel off, bypassing the switch and pressing wires together.

“Anything?” she asked.

“The batteries are still dumping! It’s some kind of cascade reaction!” Sunburst’s eyes went wide. “She’s going so fast…”

"Damn!" Sparkle swore. "Can you get through to Sunset? Maybe she can--"

“Doctor!” Dust yelled, her voice dissolving into static as she left radio range. The blip on the sensors shot right off the charts.

Sunburst swallowed as everything went silent. “All readings are dead. She’s… completely left our screens.”

Dust was gone.

"Doctor Sparkle's detection range is far better than the military's," Ensign Alias reported. "I've already alerted the EIS as per your instructions, Ma'am, but they say there's nothing they can do."

"What about the Magus Corps?" Cadance asked. She looked down at the map of the world in the War Room as if she could find Lightning Dust just by squinting.

"No results on scrying spells," Alias said.

"Of course not," Sunset said. "I didn't have any luck trying to track her. If I couldn't do it, the magi are a waste of time."

"Sorry," Cadance said, quietly.

"No, it's..." Sunset closed her eyes for a moment. "You've been a big help, Cadance. If Celestia was here she'd probably have made things more difficult instead of helping us look."

"Ma'am, if I might suggest?" Ensign Alias waited for Cadance to nod before continuing. "If she was anywhere in Equestria, we'd have found her. The whole country is on high alert. We should consider contacting our allies and coordinating efforts with them."

“I don’t care if she’s in a crater in Yakyakistan, the middle of the ocean, or vacationing in Zebrica!” Sparkle yelled, throwing a clipboard at Sunburst. “I want her found!”

“If she lost control at that speed she’s probably…” he trailed off.

“She isn’t dead,” Sparkle said, firmly. “Do you know how hard it is for a pegasus to die when crashing under their own power?”

“I don’t think that applies at several times the speed of sound,” Sunburst replied.

“Regardless,” Sparkle said, adjusting her glasses. “She has an engine heart. She’s probably close to being immortal. Lightning Dust won’t die even if she’s killed.”

“Her real heart stopped twice already, and some of the readings we had before she vanished suggested it might be happening again from the stress.”

“Her real heart stopped twice and started back up without much help from either of us,” Sparkle retorted. “And if she is dead, I want her back to find out how it happened.”

“Ma’am?” Moondancer said, pulling herself out of the bowels of the lab’s sensor system. “I have a snapshot of the last readings before she vanished.” She put down a few tools and sighed, passing over some papers. “I only did some back of the hoof calculations, but with her speed and that trajectory, we might have a bigger concern than finding her in a crater.”

“As long as we can narrow it down to a target zone we can start a search pattern,” Sparkle said. She frowned as she read some of the numbers.

“That might be difficult,” Moondancer said. “According to this, she was hitting orbital velocity. Lightning Dust might still be up there.”

Doctor Sparkle looked at the simple grave. It was identical to the hundreds of others around it, a knee-high white stone standing in formation. It had been a park a few years ago, during the war. Now it was just tombstones, as far as the eye could see.

“How long has it been since you came here?” Asked Night Light.

Doctor Sparkle didn’t look at her father. “This is the first time. He’s not buried here. The grave is just for show.”

“Your brother was always proud of you,” Night Light said, standing next to her. “He requested a transfer off the front lines just so he could keep you and Cadance safe.”

“I miss him,” Sparkle admitted.

“I do too. Your mother wishes you’d come home once in a while.”

“I can’t.”

“Work again?”

“Yes.” Twilight glanced over at him. “I need a favor.”

“What kind of favor?”

“There was an accident during a test. I need access to the Royal Canterlot Observatory to check some calculations using the equipment there.”

Night Light sighed. “I should have known this would just be about work. You can submit a project proposal like everypony else. If that’s all you wanted to talk about, I’ll be going.”

“Wait!” Twilight said. She hesitated. “I… Dad, it’s one of my friends. She’s gone missing.”

“You have friends?” He stopped mid-step to look at her in surprise.

“He told you to do it yourself?” Night Light asked, as they walked through the streets. They were busy, or at least as busy as they got these days. It was almost all children and the elderly. Everypony who could fight had been called to service.

“Kevin told me it was for my own good,” Sparkle said, sourly. "I think he just hates public speaking. He could have easily taken my place at the conference."

Night Light laughed. “Sounds like he’s looking out for you. You need to get out more. Odd name though.”

“He’s foreign,” Twilight said. She stopped, looking across the street. There was an old bookstore there, hardcovers in the windows fading in the sunlight. The mailslot was stuffed full of flyers and junkmail, papers of condemnation taped up behind the glass.

“When did they close?” Twilight asked, quietly.

“A few years ago,” Night Light said. “You used to shop there, didn’t you?”

“Mom used to have to dangle a book in front of me to get me to follow her out,” Twilight said, smiling sadly. “I can’t even remember the last time I read a book just for fun.”

“You’ve been working too hard,” Night Light sighed. “You’re going to burn out. I’m worried about you. Why don’t you take some time off and come home? Invite your friends over, even. It’d be nice to have you there.”

“I…” She nodded. “Once I can rescue Lightning Dust. I promise. I'd love to have dinner at home again.”

The Canterlot Observatory was the largest in the nation, located in Canterlot not just to be close to the center of political power but also so that they could stay updated from Princess Celestia on planned times for astrological events. Unlike on most worlds, in Equestria meteor showers were by appointment only.

Doctor Sparkle frowned as she looked around the dusty halls.

“Shouldn’t there be more ponies here?” she asked.

“Most of the interns either joined the military or found a way to get out of it. I think my lab assistant fled to Zebrica and claimed it was for her thesis research.” He chuckled. “The rest of us are fighting over the last scraps of the grants we’ve still got.”

“Sorry,” Twilight muttered.

“You don’t go into pure science to make money, but it sure does help if you have enough to keep the lights on. Doing math in the dark is really hard!” He shrugged. “Come on. You said you brought some data?”

“We were tracking Lightning Dust with several types of scrying spells. We have readings right until she left our detection range.” She pulled open her saddlebags and started pulling out papers until her father helped, opening up a folder with his magic.

“Are these numbers accurate?” He whistled as he flipped the page. “Honey, I knew you were working on something big but I didn’t think ponies could even go that fast.”

“It was a magical cascade event. At most it could have lasted five minutes from the marked time on the graph.” She pointed with her hoof. Her father almost dropped the folder.

“What happened? You’ve got burns all over--”

Sparkle looked away, feeling an odd urge to hide the scars on her fetlocks and hooves.

“It was… during the attack. The one that killed Shiny.” She couldn’t meet his gaze. She’d burned her hooves killing her own brother when he’d been turned into a slave. Her parents had never known the details. Nopony had. It had all been covered up by better hooves than hers.

“I didn’t know you got hurt,” Night Light said, frowning.

“We hadn’t been talking even before that,” Twilight shrugged. “Please, Dad. One thing at a time.” She tapped the paper.

“Right,” he sighed. “Let’s just run some quick calculations…”

Night Light took her into a lab and started writing on the blackboard there, referencing the papers she had, looking more and more concerned as he got closer to a conclusion.

“You’re serious about this just being a pony? The figures are more like some of the experimental rockets they've been flying over in Germane.” Night Light asked. “You said a five-minute time limit. Fuel?”

“Batteries. It wouldn’t change her weight significantly.”

He crossed out a few numbers on his blackboard. “So we don’t need to worry about further acceleration due to loss of fuel weight. What’s the exhaust velocity?”

“It was pegasus magic. We can only guess based on calculated wingpower, but there are unique circumstances with her thaumatic field. It could be anything up to the speed of light, depending on how you want to assign variables.”

“Well, not that fast.” He held up some papers. “Relativistic exhaust would create some very impressive radiation plumes. No sign of that.”

“So we’ve been able to eliminate the most extreme possibility,” Sparkle snorted. “Dad, this is time-sensitive. Can you tell if her flight path would take her into orbit?”

He sighed and put down his chalk, taking a deep breath. Sparkle felt unsure now. He usually only had that expression when he was about to give bad news.

“If I’m right, no.”

“That’s good!” Sparkle sighed. “Now we just need to figure out where she landed.”

“It’s worse than that,” Night Light said. “With this speed, she was on the way out. This is a hyperbolic trajectory, Twilight. She hit escape velocity and kept going.”

“That can’t be right!” Twilight’s eyes went wide. She ran to the chalkboard and started checking the math.

“There’s one thing we can try to check it,” Night Light said.

“It’s the pride of the observatory!” Night Light yelled, over the sound of the gears. Around him and his daughter, the stars and planets danced around a nearly spherical room fifty paces across, with only a small area clear of mechanisms and forming a walkway to the central console. "Ignore the sound! She needs a little oil! We need to get a fresh batch of grad students in to lubricate everything!"

It was an orrery, the largest in the world, and as accurate of centuries of work could make it. In some ways one could say it was more accurate than reality -- Celestia had on several occasions made minor adjustments to the path of sun and moon to make the sky match the wheels of bronze and silver here. It had started as a desk model and had, with countless unicorns adding to it, become rather larger and more exact over the years.

“I’ve been here before,” Sparkle reminded him.

“Yes, but you’ve never seen it in action,” Night Light smiled. “Right now it’s idling and just showing what we’d see in the sky if the sun was down. But what we can do is run this back to the exact time of the accident and calculate where she is now.”

“How?” Sparkle asked, surprised.

“Same way we track comets -- we’ve got some tracers and automatic elements so all we need to do is provide the numbers and it’ll do the work for us.” He started entering information he’d jotted down into the dial. “Give my compliments to whoever built your tracking spells. Even most professors only bother with a few significant digits.”

“Moondancer,” Doctor Sparkle said. “She’s… invaluable.”

“I remember when I had a lab assistant like that. Not like the ones we get these days. I swear the interns could get amnesia every morning and nothing would change. I ended up marrying her, but I couldn't keep her in the lab!”

Twilight blushed but refused to answer that teasing barb. She got enough from Cadance.

“Okay, here we go--” Night Light pressed a button, and things started to change quickly, delicate mechanisms spinning into action and wheeling things backwards in time. A bright red line appeared near the planet, and it took Twilight a moment and a lot of squinting to make out that no magic was involved - it was actually thread being strung along very fine wire.

“It’s showing us the path she would have taken,” he explained. “Any inaccuracy is going to be mine, not the machine’s. We used this once to calculate the exact landing spot of a small comet. Or at least it would have been the landing spot if it hadn’t exploded in midair.”

Sparkle watched anxiously as it looped part-way around the planet, then kept going into the void.

“No…” she whispered.

The building shook.

“Was that you?” She asked, looking at her father.

“I hope this thing hasn’t thrown a gear. We haven’t had the funding to give it a proper maintenance check in a while…” he looked around, trying to spot a stuck gear.

“Don’t bother,” Sparkle said. “I can hear the sirens. It’s an attack.”

“What’s going on?” Cadance demanded as the whole War Room shook, knocking over the plate of snacks Ensign Alias had brought her while she read over the papers Celestia would normally have taken care of.

“We’ve got an unknown enemy contact!” Yelled Commander Raker, who had one hoof on a crystal radio set and was trying to drag information out of it with volume. “It’s just broken through the old Everfree defense line and it’s coming right towards the castle!”

Cadance flew to the main table, looking at what was being displayed there.

“It blasted through the reserve unit.” General Nickel Plated said. “They barely even had time to warn us. We’ve mobilized everything we have to try and slow it down.”

“I felt the shockwave from the throne room, General. How bad is it?”

Lieutenant Gopher Pile answered for him, paling as he listened to the report from the field. “The eighth and ninth divisions are wiped out! No reply from any of the intercept units from Cloudsdale!”

“Declare a red alert,” Cadance said. “Raise the city shields and get every weapon we have firing at the target. Somepony try and get word to Celestia!”

“We can’t, ma’am! Long-range communications are cut off!”

“Get a courier dispatched before the city shields come up, then somepony get me Twilight Sparkle! If anypony knows how to kill a monster it’s her!”

“We need to get to a shelter,” Night Light said. “There’s one not far from here--”

“I’m not leaving until this sequence is complete,” Sparkle said, watching the red line. “I need to know where she ended up!”

“She wouldn’t want you to die trying to find her, honey,” Night Light said, softly.

“I owe her,” Sparkle said, firmly.

It took a dozen unicorns to match Shining Armor’s ability to project a shield around the city, They stood in a ritual circle, powering the huge bubble around the capital.

“Get more blessed oil onto those circles!” The crew chief yelled. “Move the mirrors into place! Facing north, damn you! Use the bucking compass, don't eyeball it!”

“Rough day?” Starlight asked.

“Bunch of bucking foals,” the chief muttered. “All the good ponies in the guard are a thousand miles away in the bucking north. All we’ve got are the reserves. Half of them shouldn't even be in the Magus Corps. They're bucking children.”

The castle shook, and half of the ritual casters collapsed, horns smoking.

“Get the backups into place!” the chief yelled. He bit his lip and continued more quietly. “That much feedback… this thing is more powerful than anything we were prepared for. I don’t know how long we can keep the city safe. If Captain Armor was here we might be able to hold out for a little longer, but...”

“You can’t win just by defending,” Starlight said. “Get somepony to help me with the suit.”

“Come on!” Night Light grabbed his daughter as the observatory shook again.

“Oh my stars,” Sparkle whispered, looking back at where the red line had ended, the thread pointing right at the surface of the moon.

Bronze gears rained down as the dome cracked open, the centuries-old mechanism exploding in a shower of springs and sparks.

“What is that thing?” Night Light gasped, looking through the open dome at the huge creature flying above Canterlot. It had to be almost a full-grown dragon, its body wrapped in layers of black crystal.

“It’s a Linnorm,” Doctor Sparkle said, just before the sky erupted with fire.

My greatest foes have always been the ponies closest to me.

Is it bad luck? Poor judge of character? What failing on my part turns my family and friends against me time and again?

Now I find myself with a dangerous question - do I allow this little game with Twilight Sparkle to continue? It's a danger to everything I've built, in more ways than one.

She's combined ancient magic with the latest discoveries and she has either invented techniques with the aptitude of a true genius or she has access to information that I've kept suppressed for centuries. The truth is, I'm not smart enough to know which it is.

Sparkle claims to be on the path to turning ponies into alicorns. She hasn't managed it yet. The signs would be obvious if she had - there have certainly been odd magical events, but nothing so grand as a rift to the Ascendant Plane. I know she's closer to success than she's told me.

I could stop her now. Perhaps I should. How close is she to that final gateway? Years? Months? Maybe it's just a matter of flipping the right switch and the fabric of reality will rend apart even as I pen this.

What she has created, those half-immortal soldiers, they might turn the tide of the war. It's flirting with disaster to even allow them to exist. I tell myself it's worth the risk. if I allow her to continue perhaps it won't end in the disaster I fear. Perhaps she'll help end the war before more ponies die.

I should never have let it get this far. I was focused on Sombra. The mystery of what happened to my sister. Other old enemies being too quiet for too long. Sparkle felt like a distraction. Something I could deal with at any time. I thought - even now, part of me still thinks - she could be an asset, like a dog to keep the wolves at bay from the herd.

Instead, I think she may be a wolf herself. She offered me the leash herself but I wonder if the other end is tied to anything or if it is simply the illusion of control.

I'll watch her. I'll watch the ponies she's gathered into her orbit. I'll find the ones helping her from the shadows. If she's going down the wrong path, if she becomes more of a threat to my ponies than the war raging around us, I will shut her down.

- Princess Celestia, personal journal