The train pulled up to the station in the Frozen North. The near-perpetual storm had calmed somewhat from the constant, roaring gale to merely windy. The only passengers, Shining Armor and Princess Cadance, stepped off the train in their cold-weather gear. Despite the reports, the station appeared to be in good shape. The rest of the train that had been abandoned, however, was markedly absent. Shining checked around for any signs of danger or survivors. He found neither.

Cadance stood captivated on the station platform. Her eyes were fixed on the glowing spires in the distance. She had only ever seen crude illustrations of the empire in Celestia's ancient, worn textbooks. No artist could every truly capture its beauty.

Shining poked around in the surrounding area at some suspicious shapes in the fresh snow. Without digging very far, he found the wreckage of the rest of the troop transport train. The steel frame of the train cars had been mangled into a pretzel.

"Oh... we need to go. Now!" Shining said, turning a whiter shade of pale.

"Then let's go!" Cadance said, heading toward the empire.

"What? No! We need to leave on the train. We need the rest of the Equestrian Army!" Shining said, chasing after her.

"No. We came here to protect the empire. And we will. As soon as we get there, you cast your shield spell," Cadance said. Shining looked behind them as the conductor put the train in reverse, departing from the station, and heading back to Canterlot. They were stuck here until his sister and her friends arrived on the next train.

A howl came up from the distance as they ran. Shining had never in his life heard the wind make such a horrid sound. He felt it as much as he heard it. I made his fur crawl with chills more than the bitter cold ever could. A massive shade moved towards them. It was darker than the space around it, like a rain band. But it was moving fast, and against the wind, and very much in their direction.

"Run, RUN!" he yelled. The deep snow impeded his speed. It clung like cement on his hooves, weighing him down and sapping his energy. They were still a decent ways away from the outskirts of the empire. Shining ran as he took deep, panicked breaths. His lungs burned from the extremely cold air. The shadow was getting closer much faster than the empire was. His legs ached in fatigue. He felt a sudden dread, like a pit in his stomach. It was like he had fallen out of a window, and he was looking at the ground rushing up at him. It was the stark realization that he was about to die.

He turned to face the monster. At the very least, he could buy his wife enough time to make it to the empire. He readied his horn to attack. At the last moment, something grabbing him and picked him up into the air. He looked down at the pink hooves wrapped around him as Cadance carried him, flying through the air towards the empire. Just as soon as they passed the first crystal spires the air around them changed. It was like they had stepped into a warm, spring day. The shadow, close behind them slammed into an invisible wall and shrieked.

Cadance recognized the aura of her aunt's magic. Celestia and Luna must have shielded the place from the cold when they battled the king the first time. But even though the spell had been preserved along with the empire, it was still finite, and increasingly brittle under the barrage of attacks by the creature outside.

"Shining! Your spell!" Cadance said. Shining hurt, inside and out. He felt like he was going to throw up. But he summoned what strength he had and focused it into his spell. A bolt of magenta arced from his horn, up into the shield spell around the empire, refreshing it with new strength. For how long it would hold, he could not say. But hopefully he would be ready to recharge it before they had to find out.

The shadow outside slinked away, vanishing in the distance. Celestia said that it had been banished to the Frozen North. Without the strength of the empire, it would be unable to leave this place and be a threat to Equestria. And as long as the shield held, they were safe inside. But now they, too, were trapped here, at the edge of the world. But they were not alone.

"Come on, we need to get to the palace," Cadance said. Shining began to follow her, but stopped and looked back. Out beyond the edge of the shield, across the frozen wasteland, back towards the train station. Twilight and her friends would be arriving in a few hours.

"I'll need to come back and keep watch for Twilight and her friends," Shining said. "They have no idea what they're heading into."

Twilight's imagination ran wild while she rode on the train. All she needed to do to protect the empire was stop the unicorn king. She had gone up against more powerful foes like Nightmare Moon and the very Spirit of Chaos, himself. A mere unicorn would be cake compared to that. Shining knew an entire suite of combat magic. In all probability, he had already dealt with the king, himself.

The more she thought about it, the less she worried. She would get to the Crystal Empire, and it would just be a vacation for her and her friends. And she would find a way to get her brother alone with her again and...

Twilight shifted uncomfortably in her seat. The weather outside the train had deteriorated as they got further north. The howling wind and blustering snow drowned out the chug of the locomotive. The fading sunlight vanished altogether behind the dense cloud cover.

"End of the line," The conductor announced as the squealing brakes of the train slowed it to a halt. The door to the train car opened. Twilight and her friends moved to the exit. She shielded her face from the biting wind with her her hoof.

"Ha, and you all made fun of me for packing so many scarves," Rarity said smugly.

"Twilight!" a stallions voice called out from the distance.

"Shining Armor!?" Twilight called back. The white stallion galloped towards her, donned in a heavy scarf and visibility goggles.

"Twilie! You made it!" he said, taking off the goggles to see her at last. They ran to each other and embraced in a hug. Twilight could have just stayed there forever, even in the freezing cold, to just hold him. He broke the hug quickly, as the smile ran away from his face.

"We better get moving," he said in a serious tone. "There are things out here that we really don't want to run into after dark."

"What kind of things?" Fluttershy asked.

"Let's just say that the empire isn't the only thing that's returned," Shining said ominously. They followed him towards the Crystal Empire. The wind was against them, slowing their progress. "Something keeps trying to get in," Shining shouted over the gale. "We think it's the unicorn king that originally cursed the place."

"But Princess Celestia said I was being sent to find a way to protect the empire," Twilight said. "If King Sombra can't get in, then it must already be protected."

A fell voice roared over the noise of the wind.

"That's one of the things, isn't it!?" Fluttershy shrieked. Shining felt his fur stand up from worse than cold.

"We have to get to the Crystal Empire now!" Shining yelled. A column of shadow rose up behind them, terrifying green eyes blinked open in it and gave chase to the group of ponies as they ran for their lives towards the light ahead of them. The cloud of shadow was unperturbed by the wind, moving faster against it than the ponies. As before, it was closing the distance on them faster than they could get to the empire. Shining needed to buy them time. "Almost there..."

If they could not reach the shield in time, perhaps he could bring the shield to them. He tried to focus his magic to enlarge the empires shield to extend outwards to them. But he hadn't the time, strength, or focus for something so grand. He stopped and turned to face the shadow monster. It worked. It stopped to square off against him, letting the others escape. Shining fired a couple quick shots of arcane energy at it. It dodged them with ease. It didn't matter. He was just trying to stall.

Sombra realized this, and swooped down to kill this interloper once and for all. Shining readied his spell. It was a small spherical shield, just enough to surround himself. It was all he could manage with what strength he had left. The king hit it with the force of a train. The shield did not shatter. It was made flexible to give like a resilient balloon. The shield squished and warped, compressing until Shining's horn penetrated through it. Sombra's death hex merely attacked Shining's horn, embedding it with inhibiting crystals. The shield rebounded like a compressed ball and launched Shining backwards away from the king. The last of his magic fizzled and the shield evaporated as he was sent tumbling through the barrier around the empire.

"Oh no! Shining Armor! Your horn!" Twilight cried, looking at the hex crystals. She helped him to his hooves. He was alive, but when he tried to call his magic to his horn, it hurt like an arcane-inhibition ring that they used for unicorn prisoners. Twilight looked at the pained expression on her brother's face. At that moment, King Sombra had added himself to Twilight's vivisection list, alongside Queen Chrysalis.

"Ooh. Sparkle-rific!" Pinkie Pie squealed in joy, looking at the pretty colors of the Crystal Empire.

"Pinkie Pie!? What the hay!?" Twilight scolded. "We almost just died and my brother is gravely wounded!"

"This is how I cope, Twilight," Pinkie Pie said, seriously. "Giggle at the ghosties. Otherwise they win. You can't live in fear."

"It's gorgeous, absolutely gorgeous!" Rarity said, unable to keep the smile from her face. "There are no words."

"Rarity, what the hay!?"

"Focus Rarity. We're here to help Twilight. Not admire the scenery," Applejack said.

"I don't see what the big deal is," Rainbow Dash said. "Just looks like another old castle to me."

"Have you lost your mind!?" Rarity scoffed. Rainbow and Applejack snickered and hoof-bumped. Rarity realized that she was being messed-with. "Very funny."

"Dash, Aj, what the hay!?" Twilight snapped. "There is a giant smoke monster just outside the empire waiting to kill us all! Can you please take this seriously!?"

"Twilight, it's okay," Shining said, putting his hoof on her shoulder to calm her. She was nearly in tears. He pulled her into a hug. "It'll be okay." She had a dubious expression. "And even if it isn't..." he trailed off, thinking about the numerous times in his life he was so certain that he was going to die. After all that, things like a giant killer shadow monster tended to get the volume turned down. They were alive, for now. He knew better than any pony that in life, there was no certainty beyond the present. So why be miserable? "Nothing like almost dying to make you appreciate being alive," Shining said, smiling at his little sister. It got her to smile back. She hugged him for just a tad longer than he was comfortable with in mixed company. He gave her a subtle, but firm push away. They headed upstairs to the palace throne room.

Cadance sat on the crystal throne. Her horn glowed, maintaining the spell. Her head was nodding as though she was bobbing for apples.

"Cadance!" Twilight greeted, smiling with glee. The name leaped from her mouth without another thought. A part of Twilight had come to resent Cadance for taking Shining away from her. But Shining was right. Almost dying did make her appreciate being alive. And it put things other things into perspective. It made her lingering resentment seem so petty. What mattered was that Cadance was still a dear friend to her. And nothing had changed that. Cadance returned a smile of her own, trotting out to greet her with their old dance.

Sunshine sunshine.
Ladybugs awake.
Clap your hooves,
and do a little shake!

"One of these days we need to get together when the fate of Equestria isn't hanging in the balance," Cadance said with a tired groan. Now that Twilight was close enough to get a good look at her, she could see the bags under Cadance's eyes.

"Are you okay?" Twilight asked.

"Cadance has been able to use her magic to spread love and light," Shining explained. "That seems to be what it protecting it. But she hasn't slept. Barely eats. I want to help her, but my protection spell has been countered by King Sombra."

"It's alright Shining Armor, I'm fine," Cadance said.

"She's not fine. She can't go on like this forever. And if her magic were to fade... Well, you saw what's out there waiting for that to happen."

"That's why we're here," Twilight said.

"Why we're all here," Applejack said.

"Well with Cadance putting all of her strength into keeping her spell going, and me trying to keep an eye on signs of trouble in the arctic, we haven't been able to gather much information from the crystal ponies," Shining said.

"Crystal ponies? There are crystal ponies!?" Rarity said with inappropriate glee.

"Rarity, what the hay!?" Twilight said.

"But we have to believe that one of them knows how to protect the empire without having to use Cadance's magic," Shining said. "But they seem to have some sort of collective amnesia or something. All I was able to get out of one of them was something about a library."

"A library? Well why didn't you say so!?" Twilight squealed.

"Uh, I thought I just did," Shining said.

"This will be like a research paper. Don't worry Shining, I'm really good at these sort of things," Twilight said as she and her friends trotted off into the city to find the library.

"What was all that she was going on about a 'research paper'?" Cadance asked. Shining shrugged.

"Eh, it's probably just her way of coping," he said.

Twilight opened the doors to the crystal library. Halls of rows of shelves of books stretched out before her. The shelves were filled with tomes a millennium old, untouched by the ravages of time. Ancient knowledge that would have otherwise been lost to the sands of history, here, perfectly preserved.

"I just- I don't even know what to- There are no words!" Twilight fawned.

"Actually, there are millions of words. This is a library," the crystal librarian said. "May I help you?"

"Yes. We're looking for a book," Twilight said.

"We have plenty of those," the librarian said with dry snark.

"You do. You really do!" Twilight gushed.

"We're looking for a history book," Applejack said. "Something that might tell us how the empire might have protected itself from danger back in the day."

"Yes, of course," the librarian said. "History... history... ah, yes!"

"Which is where, exactly?" Twilight asked.

"I... I can't seem to remember," the librarian said, a bit flustered. "I'm not sure if I actually work here."

"We'll just take a look around. I'm sure we can find it on our own," Twilight said.

"Let's grab random books off of the shelves to read until we stumble upon the right one," Applejack suggested.

"Whoa, wait a minute, AJ," Rainbow Dash said. "You can read?"

"Rainbow Dash, what the hay!" Twilight scolded. "AJ, how about we act like time is a factor instead? I assume the history book we need will be in the history section."

"Oh yeah. That makes way more sense." They walked to the history section of the properly organized library. Twilight scanned over the books that were organized by title for a few moments until she found the one they needed.

"Boom. History of the Crystal Empire," Twilight said with smug satisfaction. "I just hope it has the answers we need." Twilight skimmed through it until she found the answers they needed. "A Crystal Faire. According to this book, it was established by their first queen and became their most important tradition. The fair was held every year to renew the spirit of love and unity in the empire so they could protect it from harm. The whole purpose of the Crystal Faire is to lift the spirits of the crystal ponies so the light within them can power the Crystal Heart so that the empire can be protected."

"The Crystal Heart?" the librarian asked excitedly. "Do you mean you've found out where it is? But King Sombra said he'd hidden it away where we would never see it again. I only hope it will still be as powerful after all these years."

"Uh... yeah," Twilight said nervously. "We need to, uh, run away now for a completely unrelated reason." Twilight and her friends ran back to the palace to tell Shining and Cadance what they had found.

"My friends and I could put the faire together," Twilight explained to Shining and Cadance. "Everything we need to know is in the book. The only thing we're missing is the Crystal Heart mentioned on the last page. It's a relic that King Sombra apparently hid."

"Wow. That's a pretty significant detail," Spike said. "It's a good thing Sombra didn't tear out that last page."

"Spike, that would be an incredibly contrived measure. If he was going to do that to prevent ponies from finding out about it, he would have just destroyed the whole book," Twilight said. "And that would have to assume that he could have foreseen this exact scenario during his reign before Celestia and Luna defeated him a thousand years ago. Even my Daring Do fan fiction writing isn't that convoluted."

"Yeah Spike," Applejack said.

"Shut up AJ! You can't even read!" Spike said.

"Spike, what the hay!" Twilight scolded.

"Dash, stop spreading rumors about me!" Applejack snapped. Rainbow Dash just snickered in guilt.

"Aww, Cadance is so cute when she's asleep," Pinkie Pie said. Everypony turned to see that Cadance had passed out in Shining's hooves from exhaustion. Her spell faded and they all watched the shield around the city evaporated. The smokey form of King Sombra appeared in the tundra beyond, bearing down on the empire. "You know what? I owe Princess Luna an apology. That pony looks like a Hokey Smokes."

"Twilie," Shining cried, looking to his sister in desperation. His wife, unconscious in his hooves. His magic, disabled by the Sombra's hex. She could teleport. She could take him along with her, away. Far away. Far enough away to escape. Without his magic he wouldn't be able to stop her from- Twilight pushed those thoughts away. Even if they managed to escape, he'd never forgiver her. She'd never be able to forgive herself.

Shining shook Cadance awake. "The empire is under attack!" Her dull eyes flittered awake and focused on the smoky black mass approaching the empire. She looked back at her husband. He couldn't give her strength with his magic, but his eyes told her all she needed to know.

I love you.

She took a deep breath and steadied her hooves with fresh resolve. She marched out onto the balcony and her horn glowed with an iridescent tinge to her usual blue magic that Rarity had never seen before. The protection spell spread out and surrounded the empire once more. Twilight and Shining exchanged nervous glances. If time hadn't been a factor before, it was now. Cadance was burning Soulfire.

"I have to find the Crystal Heart!" Shining said.

"I'll help you!" Twilight said.

"We all will!" Applejack said.

"No," Twilight said. "The Crystal Heart is useless without the Crystal Faire to lift the spirits of the crystal ponies so the light within them can power it. The rest of you need to put the faire together to renew the spirit of love and unity in the empire so they could protect it from harm! Everything you need to know is in the book."

"Yeah AJ," Dash said. "You can read it to us."

"Seriously Dash, what the actual hay!" Twilight scolded. "The empire is in peril and we could all die!"

"Pssh."

"Rainbow, I need you to spread word to the crystal ponies that there's going to be a Crystal Faire while the rest of them put it together," Twilight said. She looked at Cadance, and then back to Dash. "And I need you to do it fast."

By the stars, it was like the pegasus had been waiting all day to hear that word. The 'T' in fast didn't even make it to Rainbow's ears. The prismatic mare outran the sound waves, taking off into the sky so quickly that she left behind a hole in the volume of air that was once occupied by her body. The atmosphere collapsed in on it with a deafening boom akin to thunder following the hyper-expansion of ionized air around a bolt of lighting.

"We'll get started right away," Rarity assured the prince. "Come on Spike, we've got a Crystal Faire to put together."

"That sounds pretty promising," Shining said. "The two of us will find the Heart and you guys get that faire going." The other ponies left to get to work. He turned back to his wife, watching her burn her Soulfire. "Cadance?"

"I feel fine," Cadance said, unnaturally chipper.

"And she'll keep on feeling fine right up until she..." Twilight trailed off.

"Then we don't have a moment to lose finding that Heart!" he said with conviction. "Um, any idea where we should start looking for it?"

"Right here!" Twilight said, walking with her brother back inside from the balcony, into the throne room.

"The castle?" Shining asked.

"The king would have been counting on the fact that no pony would dare come looking for it here," Twilight said. "They'd have been too afraid to even try."

"I hope you're right," Shining said.

"You and me both," Twilight said.

"So you think we'll find it in here?" he asked. Twilight looked the the throne, remembering Celestia's words about the way the nature of the Crystal Empire's magic changed 'if fear and hatred take hold'.

"No," Twilight replied. "Because this isn't King Sombra's castle."

"Well, isn't this where he lived while he was in power?" Shining asked.

"It is. But it didn't look like this," Twilight said. She focused on the crystal structure of the throne room. She fueled her every dark thought into her magic. Every time she felt anger, or hate.

She thought about that colt that called her a nerd in magic school. She thought about the pony that was late returning the library book that she needed. She thought about Discord turning her friends into the opposite of themselves. She thought about Chrysalis trapping her brother in the caves to starve to death. She thought about Cadance.

Shining watched the magenta magic around his sister's horn turn dark. Arcs of black crackled around her horn.

Twilight though about Cadance. She though about her lying there in their bed and Shining, standing over her with his... penis. His erect penis! Her eyes were clenched shut but she could see them, in her mind's eye, as clearly as she could see her hooves in front of her.

Shining could see wisps of dark purple aura at the corners of Twilight's eyes.

Twilight could see him, there, right in front of her. She could see him, on top of Cadance with his erection. He moved between her legs and he- he was putting it in! Twilight wanted to stop him. She wanted to stop Cadance from doing that with her brother. She wanted to stop her with all her might. Cadance was fucking Shining! She's fucking him! Twilight would stop her! She would- she'd KILL her!

The bolt of black magic fired from Twilight's horn at the throne. The dark spell transformed the throne room into the shadowy version of its former self. A hole opened in the floor, revealing a spiral staircase leading down into a pitch dark abyss.

Twilight breathed a sigh of relief to be rid of the toxic magic, and the equally toxic thoughts.

"Whoa. When did you learn to do that?" Shining asked with equal parts of awe and concern.

"That was a little trick Celestia taught me," Twilight said.

"Twilie, I-" Shining put his hoof on her shoulder. "That kind of dark magic, we've been trained to defend against that sort of thing in the guard. The unicorns that use it... it taints them. It turns them into..." Shining shuddered.

"I won't let that happen," Twilight assured him.

"Nopony lets it happen. But the fact that Celestia is teaching it to you... Maybe it's different for an alicorn. The ponies that use it, the things that it shows them, by the time it takes them over, they don't even realize it. Just- just please promise you won't ever use that again."

"Okay. I promise," she said. They looked down the hole that the stairs led into. They couldn't see the bottom. Twilight pried a bit of crystal from the wall and dropped it down. They waited and listened. And waited. And listened. The echo of the impact finally made it back up to them. "Whoa, that's a long ways. And we don't have much time."

"Then what are we waiting for!? Cadance is burning Soulfire!" Shining grabbed the back panel of the throne and pried it off. He positioned it at the edge of the stairs and got on.

"Shining, wait!" He slid down the stairs in a blur. The spiral shape kept him pinned against the wall's edge. The world spun rapidly as he went in circles He braced his hoof against the wall to steady himself and to try to slow his descent. Sparks flew from his horseshoe and it quickly grew to hot for him to stand. He reached the bottom of the stairs before he could worry about burning his hoof. The panel struck the abruptly level floor and he was thrown from it. Luckily, his face broke his fall. Shining shook off the crash and orientated himself. In the small space at the bottom of the stairs there was nothing but a single door.

"Twilight! I think it's here!," he called up to her.

Shining opened the door and walked inside. The room was small and plain. The Crystal Heart sat there on a rather unassuming pedestal. Clearly the former king had no love for the item to put it in any kind of place of honor. He picked up the heart and looked at it. It was smaller than he had expected. But then he didn't know what to expect. He turned to leave. Twilight was waiting for him in the doorway.

"Oh, good! You found it!" she said. "You know, we've got some time before the rest of my friends have the faire ready to power it. And I can't think of a more private place in the entire empire for us." Twilight slinked up to him with her come-hither bedroom eyes.

"Twi, come on! Cadance is upstairs burning Soulfire. This isn't fair to her," he said. Twilight's magic began teasing his sheath. "And we promised that we wouldn't do this again after I got married," he said. "We promised that we would be good ponies."

"Shining," Twilight cooed as her magic drew out his shaft, and began stroking it. His erection grew harder than it had been since that time together with her before the wedding "we're not good ponies."

Shining's throat hitched. Deep down in his heart, he felt it. He knew she was right. He was not a good pony. He was a married stallion that lusted after his own sister behind his wife's back. His wife who was dying for him just to buy them time. And they were using it to-

"Twi, stop!" he begged. She grabbed him with her magic and pinned him down, straddling him. With the hex on his horn, he was powerless to stop her.

"You can tell yourself you don't want this, if it'll help you sleep," she said, lowering herself onto him. He groaned as he felt his cock slide inside his sister's tight pussy. She began sliding up and down on him, keeping his hooves pinned with her magic. "I will do what I must to put out the flames of my heat. I will take what is mine. You can tell yourself I forced you to do this." He moaned as she rode him. "But I can tell you are enjoying this."

The terrible truth of the words stabbed him like icy daggers. He was enjoying this. He loved it. And he hated himself for loving it. He hated how much more he enjoyed having sex with Twilight than with Cadance. She rolled over, pulling him on top of her just at he went past the point of no return.

"Twilie!" he cried out. His cock flared, throbbing and pumping. His pent-up load flooded deep inside his fertile sister. A week's worth of cum into the mare in season would surely get her pregnant. There would be no way for him to hide this.

"Well, well well!" Cadance said from the doorway. Shining's eyes went wide at the voice.

"Cadance! It's not what it looks like!" he cried.

"Really? Because it looks like you're balls-deep into cheating on me! With your sister of all ponies, you disgusting pervert!" Cadance yelled. Cadance grabbed him with her magic and carried him upstairs. Without his magic, he was helpless. She carried him out into the empire's square, tying him to a post on a cart. She hung a sign around his neck that said 'sister fucker'. His limp penis hung in front of him, still wet with Twilight's juices. Cadance spat on his face and then turned to begin pulling the cart. A mob formed around him. At the front of it was his parents.

"Mom, dad!" he begged for help. His parents gave him a look of utter disgust and they cast the first stones. Then the rest of the ponies began throwing rocks at the defenseless stallion as they all chanted 'sister fucker'. Cadance pulled him to the other end of the square to a platform where Celestia and Luna waited for him, surrounded by every Royal Guardpony he ever knew.

"Shining Armor," Celestia addressed him. "For your infidelity, your marriage is hereby annulled. You are stripped of the title of 'Prince', of 'Captain', and you are hereby expelled from the Royal Guard!"

"Shining Armor," Luna said, "For the crime of..." she sneered at him. "incest, you shall be hereby gelded!"

"Shiny," Twilight said from down below, "At least I'll still have your foal."

"Give me the knife!" Cadance said, grabbing it from the operating table. She pointed it at his balls. "These are mine!"

"Shiny!" Twilight cried. Cadance brought the knife down.

"SHINY!" Twilight screamed.

Twilight screamed as she finally reached the bottom of the stairs and tackled him. His cheeks were dripping with his tears. "Shining what's wrong, why were you just staring at this... doorway..." she asked, looking at wall in the door frame. Dark magic shot out from the door frame at her. He saw his sister being brought to tears. "What!? What do you mean you don't want me as your student anymore!? But I- I-" Twilight sobbed. Shining slammed the door shut. "Wha- what happened?" she asked.

"King Sombra's dark magic," Shining said. "A doorway that leads to your worst fear."

"I was back in Canterlot. Celestia said she didn't want me as her student anymore," Twilight said as she wiped her eyes. "She was sending me away for failing my test." He wrapped his hooves around her.

"Twilight, I've known you for your whole life. I know you well enough to know that the only thing you can't do is fail. You don't know how to." She hugged him back. She could feel the wetness of his cheek on hers. She couldn't imagine what horror could have driven her fearless big brother to such a state. She glared at the door frame and hit it with her magic to disable the curse. The doorway opened into another space. She let go of him and walked through. "What's in there?" he asked. Twilight looked up.

"Stairs. Lots and lots of stairs," Twilight groaned. Shining joined her. She could still see the damp patches of fur on his cheeks. "What did the door show you?" she asked. He gulped.

"The worst-" he said, trying to keep the tremble from his voice. "Sombra winning," he lied.

"Well we're not going to let that happen!" she said with conviction. She ran up the stairs. He followed after her. His eyes automatically followed the pony in front of him. His angle below and behind her gave him a very particular view. He found his eyes being drawn to when he knew they ought not be. Her flank flexing and shifting as her tail swished from side to side. He felt a primal part of him stirring. He was not a good pony. He tried to bite back his arousal. He tried to think back on the visions that the door had shown him. Something occurred to him.

"What if this is just more of his magic?" he asked. "He makes a door that leads to your worst nightmare. Why not a staircase that goes on forever?" Twilight thought about it for a second, looking up at the spiral of stairs. Her eyes lit up.

"Hold onto me," she said. Shining felt his loins twitch.

"Uh, what?"

"Hold onto me!" Twilight lifted him with her magic. He could only float there as she placed him onto her back as though he were mounting her. It was just like in the horrible vision. The nice part of it anyway.

"Uh, Twi, we don't have time for-" She cut him off as he spell finished and they were flipped upside down and fell... up. They began 'falling' up the smooth slope of the underside of the stairs.

"WHOA! Hahaha!" Twilight laughed out loud as they slid along the smooth slope. It was the same hearty, innocent laugh he remembered from her when they had gone sledding in the snow as foals. But it was all he could do to keep his hooves wrapped around her and hold on. And it took all his willpower to keep himself from getting hard on top of her. "I actually studied gravity spells thinking it might be on my test! Turns out I was prepared for this! Woohoo! Hahaha!"

"So about that Crystal Heart...?" one of the crystal ponies asked Fluttershy down in the palace courtyard.

"Oh. Um, well, you see-"

"Where is the Crystal Heart?" another crystal pony asked Applejack.

"The thing is, uh-"

"When are you going to get the Crystal Heart?" another asked Pinkie Pie.

"We uh, we uh-"

"Why are you not getting the Crystal Heart now?" another asked Rainbow Dash.

"Uh..."

"Spikey, why don't you run and check on how Cadance is doing while we manage the crowd?" Rarity suggested. Spike ran up into the palace to head up to the throne room.

Twilight and Shining reached the top of the stairs. Twilight quickly disabled the gravity spell and they fell down onto the floor of the room at the top of the spire. Shining landed on top of her. Twilight couldn't ignore the semi-firmness in his sheath pressing against her flank. As much as she wanted to push back and rub against it, she knew they didn't have time to indulge themselves.

"The Crystal Heart!" Shining said, spotting the relic floating in the middle of the room as he got to his hooves. Twilight focused on her mission and ran to grab the Heart, inadvertently triggering the hidden trap. She leaped to grab the Heart but only knocked it away with her hooves as the black crystal walls shot up around her. The Crystal Heart skittered across the floor, sliding off of the edge of the spire.

"Oh shit!"

Cadance stood at the balcony railing, her spell burning her Soulfire. She would hold the spell for as long as she had to until the empire was safe. Or until it killed her.

Spike walked into the throne room and saw Cadance at the balcony with her back to him. He walked out onto the balcony to talk to her.

"Hey Cadance, is there anything I can d-" The falling Crystal Heart clocked Spike square in the head and bounced onto the balcony floor in front of him. Cadance turned to look at him, seeing the Crystal Heart beside him.

"Spike! You found the Crystal Heart! You're a hero! Come on, let's go!" She picked him up and the Heart with her magic.

With her magic carrying the Heart, the barrier spell lapsed. The monstrous form of King Sombra closed in on the empire as Cadance flew down to the mob in the courtyard.

"The Crystal Heart has returned!" Cadance announced to the crystal ponies. "Use the light and love within you to ensure that King Sombra does not!" All the crystal ponies used the light and love within them to power the Crystal Heart, sending out a blast of magical energy. It turned everypony crystalline, destroyed the crystal cage around Twilight, the hex on Shining's horn, and made King Sombra explode into a million tiny pieces. Rarity looked around at all the sparkling, glimmering, shimmering, crystalline ponies and nearly had an aneurysm. She grabbed the nearest stallion she could and, in so many words, demanded that he mate with her. At the top of the spire, Twilight ran over and wrapped her hooves around her brother, tackling him to the floor.

"Oh my gosh! We did it! We save the empire!" Twilight squealed. "Look at you! Look at me! We're see-through!" She looked down at herself. "We're like a living anatomy book!" She looked through herself at Shining under her. She could see what she was feeling where she was straddling him. She could she his semi-hard shaft still inside his sheath. She couldn't keep herself from grinding her hips against him. Shining couldn't keep himself from his involuntary reaction.

She watched his erection grow out of his sheath, sliding under her marehood, pinned between them until it emerged out from under her, growing harder with each beat of his heart. She lifted her hips off of him and he took to thinking she was done playing and he tried to sit up. She took his cock in her hoof and angled it upwards towards her pussy.

"Twi, no!" he objected. "We promised we weren't going to do this again after I got married!"

"I just want to see what it looks like inside!" she said in genuine curiosity. Before he could tell her no again she lowered herself back down onto him. The air rushed out of Shining's lungs as soon as he felt himself slip inside her. He truly did miss this more than he wanted to admit. Least of all to himself. "Oh my gosh, oh my gosh! Look!" Twilight squealed as her hips met his. Shining had no choice but to look. Even with his eyes clenched shut, he could see right through his eyelids. Shining's cock filled her pussy perfectly completely. It was as though it had been molded around him. It was the exact right depth for his length. His tip rested snugly against her cervix.

"I knew it felt like a perfect fit! And now I can see it is! We're perfect for each other." Twilight said as she started to move up and down on him. They could both see in detail exactly what each of them were feeling. He could see every muscle he felt squeezing and massaging him. She could see every contour of his veiny shaft sliding in and out of her. She could see the cloudy white swirling in his balls. There was a lot. "Those look full," Twilight said. "We'll fix that!"

"Ngh, Twilie!" Shining moaned. His fear and guilt melted away under her. It just felt so good, so right. She was right. There was a lot. It had been too long. He wanted this. He needed release. His hips thrusted up to meet her. "F-fuck!" he panted. She looked down at his shafted thrusting in and out of her.

"Yes! Yes! Fuck me, big brother!" she moaned, appealing to the taboo nature of their act. Shining started to hyperventilate as the vision of all his worst fears came rushing back.

"Cadance is going to see. Everypony is going to see! Celestia is gonna have me sent to the gelding clinic and- and-" Shining realized that his horn was no longer hexed and his magic pushed her off of him. "Shit. Shit!" he cursed as harsh sobriety washed away his lustful haze.

"Shining, it's okay! There's nothing to worry about."

"Nothing to worry about!?" he said incredulously. "Twilight, I'm married. I'm a prince! I have SO MUCH to worry about. And I can't have a secret relationship with you on top of that! I already feel bad enough for what we did at the wedding. I can barely sleep, and things between me and Cadance have been really strained. But I obviously can't tell her why."

"Well, maybe you just need this as stress relief," she said.

"This isn't stress relief. This is stress increase!" he said.

"But you obviously like it," Twilight said.

"That doesn't make it okay," he said. "A few minutes of bliss aren't worth the lifetime of torment. I'm scared all the time, Twilie. I'm scared that we're going to get caught. I'm scared that we're going to lose everything we care about just to indulge in each other. But most of all..." He sighed and looked away. "I'm scared that we'll get away with it. You have to be the one to stop. You know how hard it is for me to say no to you. You- you know how weak I am for you, and you're preying on that weakness. You know that there is a possibility that I- that I just might give everything up for you. And that terrifies me. You're Celestia's star pupil. I'm the Captain of the Royal Guard. A prince now. We're supposed to be good ponies."

Twilight considered his words. She wondered what she would actually do if they ever were found out. Would she deny it? Would she run away? Would she give everything up for him, too? Even if it meant hurting everyone else she cared about? Her friends, the rest of her family, Celestia and Cadance? The more she thought about it, the more it troubled her that the answer wasn't immediately 'no'. Twilight put her hoof on his.

"Maybe we're not good ponies," she said. He yanked his hoof away from her.

"Maybe you're not," he spat. "But Cadance is a good pony. And she deserves to have a good pony for a husband! Now if you'll excuse me, I need to go downstairs and see to my wife. When you come down, it better be as my sister." His shameful erection finished retreating back into its sheath. He walked to the stairs and looked at her a final time before leaving. "But never again as my lover. Is that clear!?"

"... Crystal."

Princess Celestia watched the aurora streak across the evening sky from the north, signaling the success in the Crystal Empire. With a smug grin, she looked at her sister beside her, leaning her head to touch her horn with hers. Luna hesitantly returned the gesture.

"Well Luna, it looks like you owe me a cider."

"We shall see," Luna replied before she left to begin her shift.

Celestia took Starswirl the Bearded's ancient spell book from her bag. She flipped to the last page where his final spell remained unfinished.

"Indeed we shall," Celestia mused to herself.

In the Crystal Empire, everypony was celebrating the return of the Crystal Heart and the defeat of King Sombra, hailing Spike the dragon as a hero. Shining Armor ran into his wife's hooves and they embraced each other. She filled him in on what he had missed. Everypony was in high spirits.

Everypony except Twilight Sparkle.

Twilight remained at the top of the spire for how long, she didn't know. So much had transpired so quickly. Sombra was defeated. She should have felt relief. Instead she felt only dread that she would have to carry on. The imminent threat of her demise that King Sombra presented has given her a strange sense of comfort. It gave her focus about what was most important to her. And now that it was gone...

Twilight sighed and began trotting down the stairs.

Princess Celestia had told her that she alone was to save the empire. But it hadn't been the case. She had failed the test. And now she had alienated herself from her brother even more so. She could feel all the things she cared most about eroding away from her.

She was hardly alone. She was surrounded by thousands of ponies who were the happiest they had ever been in their lives. Their world was saved while it felt like hers was ending. That was what loneliness really felt like, Twilight realized. Not being alone, but being surrounded by ponies that made you feel alone.

She had never wanted to hurt anypony. She used to believe that all you needed was love. And that love would beget more love. That the more you gave, the more you would have. That if she loved her brother, that he could love her back, simple as that. But if she had learned nothing else, it was that love, like life, was never simple. And it would never be enough to simply want for something.

~

Spike sent off Shining's letter with a quick burst of green fire just before Twilight's friends came up from the courtyard. Twilight reached the throne room shortly after her friends and they all ran to hug her. She smiled reflexively. Pinkie Pie knew smiles, and Spike knew Twilight. They could both tell when her smile was fake.

"Are you worried about your test?" Spike asked. Twilight nodded. Princess Cadance and Shining Armor returned to the throne room from the balcony to join them. Twilight felt her throat closing up. She couldn't look her brother in the eyes. Cadance was practically glowing.

"The love and light inside the crystal ponies has revitalized her," Shining explained to Twilight's friends. "They're hailing her as the 'Crystal Princess'."

"I always thought the heart for my cutie mark had to do with my love magic," Cadance said. "But now I see that it's the Crystal Heart! It's my destiny!"

"So I guess that means we'll be staying here for a while," Shining said.

At the edge of the world, Twilight thought. As far away from me as possible.

"But we should probably be getting back to Canterlot as soon as possible to tell Princess Celestia that the empire is safe," Spike said. "Right, Twilight?"

"Yeah... sure," Twilight said, turning to leave. Her friends reluctantly followed after her. As did Shining and Cadance.

As they reached the edge of the empire, the crystalline effects wore off of them, much to Rarity's disappointment.

"Everything's going to be okay," Shining said as he caught up to Twilight to walk her and her friends to the train station. Twilight's friends assumed he was talking about her test with Celestia. But the siblings knew better. "You've got to stop saving my rump like this. It's starting to get embarrassing," he added, trying to cheer her up in recalling her role in saving the wedding. "Besides, it's just a test. Maybe she'll let you retake it," he said jokingly, trying to give her poor mood some levity.

"Shining, what the hay?" Cadance scolded him.

"I don't think she's going to give me a new test," Twilight said, getting on the train without looking back. It was a little unnerving to her how well Shining could act like everything was fine. But she would have time to worry about things with him later. First she had to deal with Princess Celestia back in Canterlot.

"It's beautiful," Celestia said to Twilight of the aurora outside the castle window.

"I wish it had been me that ultimately made it so," Twilight said. "But it wasn't."

"Twilight, as I understand it, Spike brought Cadance the Crystal Heart because you weren't sure how quickly you could escape the tower. You weren't willing to risk the future of the citizens of the Crystal Empire in an effort to guarantee your own," Celestia said, holding a scroll in her magic. Twilight recognized her brother's writing, a letter he'd had Spike send to Celestia before they'd left the empire. Clearly he had slightly enhanced the truth in Twilight's favor. "Far better that I have a student who understands the meaning of self-sacrifice than one who only looks out for her own best interests."

"Does this mean...?" Twilight asked. Celestia nodded. Twilight ran from the room in excitement.

Outside, Spike paced back and forth unreasonably close to the castle doors. Twilight threw open the doors, giving Spike his second concussion in as many days. "I passed!" she announced to her waiting friends.

~

Back inside, Luna brought her sister a mug. "Here's your cider," she said, before taking a sip of her own.

"Luna, it's like, nine in the morning," Celestia said with disdain.

"Pssh. Yeah. For you," she said before chugging her drink. "Does that mean you're not having yours?" Celestia gave her sister the other mug back. Luna drank that one, too. "Enjoy your day being sober. I'm going to bed."