> Sunrise, Sunset
>  by Summer Knight
> --------------------------------------------------------------------------

> Sunrise, Sunset
> --------------------------------------------------------------------------

	Spike's belch shattered the quiet of the Golden Oaks Library. 
“Letter for you, Twilight.”
“So I heard,” Twilight giggled. “Let's see.”
Spike handed over the letter. Twilight unrolled it with her magic and held it in front of her, her purple eyes darting back and forth as she scanned the contents.
“What does it say?”
“It's from Cadence,” Twilight said in surprise. Nopony other than Celestia had ever sent her letters through Spike, though she knew that it could be done. 
“Dear Princess Twilight,” she read. It was an oddly formal tone for her former foalsitter to use. “I am sorry to call you on such short notice, but I need you and Spike to come to the Crystal Empire immediately. I have sent a chariot to bring you here, which should arrive at your home within the hour. I apologize again, but it is extremely urgent. With love, Princess Cadence.”
“An hour?” Twilight shouted. “Oh my gosh, we need to get ready! Oh, I wish she had told me more about what's going on. What books will we need? Should we bring food? What if—”
“Twilight, calm down!” Spike said. “I'm sure that if we needed anything in particular, Princess Cadence would have told us.”
“You're right, Spike.” Twilight took a deep breath. “Okay, let's think about this logically. Since we don't know what's going on, we need to be prepared for the widest possible array of situations.” She rattled off a list of a dozen books for Spike to pack, along with some odds and ends. “That should cover the basics.”
“What about the others?” Spike asked. “Are they coming with us?”
Twilight read the letter again, frowning. “No,” she said finally. “Cadence didn't say anything about bringing them along, and we wouldn't all fit into a chariot anyway. Looks like it's just you and me this time.”
After a frenzied hour of preparation there was a knock at the library door. Twilight took a moment to make sure she was presentable, then opened it. 
She promptly gasped and a blush spread across her face. “Flash!” 
“Your Highness.” Flash Sentry bowed deeply, then stood up and smiled shyly. They stood there looking at each other for an awkward moment.
“Not the time, Twilight,” Spike said, impatiently pushing her out the door. 
A chariot sat near the door with another pegasus guard waiting to pull it. After making sure that Twilight was safely aboard, Flash took his place next to the other guard and they rose into the sky. Twilight tried to strike up a conversation, but the guards were pulling for all they were worth and the rushing wind made it impossible to hear. 
Sooner than Twilight would have thought possible, they were descending into the Crystal Empire. The chariot landed outside the palace and Twilight's two guards escorted her in. They led her to the throne room, where a certain pink alicorn was waiting to greet her.
“Twilight!” Cadence exclaimed as they entered. Ignoring proper decorum, she swooped down and caught Twilight up in a hug. “And you too, Spike. Thank you both for coming on such short notice.”
“Good to see you too. Where's Shining?”
“He was called away on a diplomatic mission to Gryphonia. I'm afraid he won't be able to join us.”
“What's going on, Cadence? Your letter didn't say much.”
“No, I'm sorry about that. I was in such a hurry to send it that I didn't include much detail.”
“Well, what's the matter?” Spike asked.
Cadence took a deep breath. “It's about the mirror to the human world,” she said. 
“Of course!” Twilight exclaimed. “It's been two and a half years since we went through, Spike. Thirty moons. Does that mean the portal is open again?”
“Yes, and somepony has come through it. She says she knows you.”
“Sunset Shimmer?” Twilight gasped.
Cadence nodded. 
“Where is she?” Twilight asked. 
“We arrested her,” Cadence said.
“What? Why?”
“She's a criminal, Twilight. Last time she came here she stole one of the Elements of Harmony.”
“She's changed!” Twilight pleaded. “Please, Cadence, at least let me talk to her.”
“I planned to,” Cadence reassured her. “That's why I asked you to come here. Sunset said that Equestria is in danger and she asked to speak with you. She willingly turned herself in once I promised to write to you.”
“Can I go see her now?” 
“Yes, I think that would be best. I'll come with you.”
The two princesses and Spike, escorted by a crystal pony guard, made their way down several flights of stairs to the dungeons. 
“These dungeons haven't been used since King Sombra's time,” Cadence explained as they walked. “I was hoping they would never have to be used again, but they're the only place we have that can hold a unicorn like Sunset. The cages are made of a special type of crystal that disrupts magic spells, so she can't teleport out.”
“I see.” Twilight wasn't happy to think of someone she counted as a friend locked up in a cage like that, but based on Sunset's history she couldn't fault Cadence for it. 
“Here she is, Your Highnesses,” the guard announced.
“Sunset!” Twilight called out, going right up to the cage despite the guard's attempts to keep her back.
“Twilight!” Sunset exclaimed. She stepped forward and extended a hoof hesitantly, which Twilight reached out to take. “Thank goodness you're here.” 
“What is it, Sunset? What's wrong?” Sunset's hoof was shaking, and the pony herself did not look well at all. Her eyes were baggy and bloodshot as if she had not been sleeping well, and she was very thin. 
“Oh Twilight, Equestria's in danger and it's all my fault!” she cried.
Twilight gently shushed her and stroked her hoof comfortingly. “It'll be okay, Sunset. Tell me what's happened.” 
Sunset took a deep breath to calm herself. “Things were great for a while after you left. I finally had friends—real friends—and I was starting to make amends for how horrible I'd been to everyone. I think I was happier than I've ever been. But turning into a demon, a giant magical battle, those things don't happen in the human world. Needless to say, what happened that night attracted a whole lot of attention. They wanted to know what happened, where the Element came from, how to get here, and I...” she looked away, unable to meet Twilight's eyes, “I told them everything.”
“But I don't understand,” Twilight said, “why does that mean that Equestria is in danger?”
“You don't know what they're like, Twilight,” Sunset said quietly. “Your only experience with the human world was in a school, and what you did there was amazing, but you haven't seen what they're capable of. They wanted to know everything about Equestria because they think they can harness its power. Twilight,” she stared up into Twilight's eyes, “as soon as they realize that the portal is open, they're going to invade.”
“Invade?” Cadence shouted. “You knew what they wanted to do, and you still told them how to get here?”
“I didn't have a choice!” Sunset cried. “I tried to resist. I held out as long as I could, but they were very persistent and very skilled.” 
A horrible suspicion struck Twilight. The wasted thinness, the baggy, frightened eyes... "Did they torture you?” she asked quietly.
Sunset bit her lip and looked away.
“Sunset, answer me." Twilight's stomach was twisting itself into knots.
“Not like you're thinking,” Sunset said quietly. “Not with hot irons or lashes or anything like that. They just made me totally helpless. I had no control at all, over anything. Meanwhile, they would tell me every day what a horrible person I was, how many people I nearly killed, and how it would only happen again if I didn't tell them what they wanted to know.” 
“Psychological torture is still torture,” Twilight said softly. “Oh, Sunset, I'm so sorry.” She gave Sunset an awkward hug through the bars. “Is there anything I can do?”
“It's not important right now,” Sunset said, pulling herself free from Twilight's embrace. “We need to figure out what we're going to do.”
“Twilight, can I talk to you for a moment?” Cadence asked. 
With a final concerned look at Sunset Shimmer, Twilight went to join the other princess. 
"Are you sure she's telling the truth?” Cadence asked quietly. “You told me that she was very good at creating conflict. She even drove your friends apart for a while. This might be some kind of plot to cause trouble between Equestria and the human world.”
“Just look at her, Cadence. She's obviously been through something terrible,” Twilight said. Her heart burned with anger and the desire to help her friend recover from the ordeal. “Besides, what would she gain from a lie like that? If nopony else comes through the portal, then that's that. It's not like we're going to invade, right?”
“Right,” Cadence said, though she still looked worried. “Just be careful, okay?”
Twilight looked back toward the cage and her ears drooped. To leave her locked in a cell after all of that... 
“Cadence,” she said suddenly, “if I promise to take full responsibility for Sunset Shimmer, would you let her go?”
“What?” Spike shouted. He'd been keeping quiet from an awkward sense that all of this was a bit over his head, but that part he understood. “Twilight, don't you remember all the terrible things she did? All the things she did to you?”
“Of course I do, but she's changed. I think she's telling the truth.”
“Twilight,” Cadence said sternly, “I want you to know how serious this is. If you take responsibility for her, that means that anything she does can be held against you. If she tries something like she did before, it would be both of you in jail.”
“I know that,” Twilight answered determinedly, “but I'm willing to take that risk.”
“Alright, if you're sure,” Cadence said.
“I am.”
Cadence nodded to the guard. “Open the cell. Let her out.”
The crystal pony looked uncertain, but he did not question his princess. He pulled a key out of a small pouch and unlocked Sunset's cell. 
Despite the door standing wide open, Sunset did not leave the cell. “You don't have to do this for me, Twilight.”
“I know,” Twilight said. “It's my choice, and I'm choosing to believe in my friend.”
Sunset bowed her head. “Thank you.”
“So what do you suggest we do about this threat from the human world?” Cadence asked. 
“The portal is only open for three days,” Sunset replied. “All we have to do is hold them off until it closes. We'll want to mount our defense on this side of the portal so that we can take advantage of our magic.”
“Sunset, this is the Crystal Empire,” Cadence said. “Crystal ponies can't use magic.”
“Even so, we have two former students of Princess Celestia and you on our side, and Twilight has the Element of Magic.”
Twilight and Cadence looked at each other uncomfortably. “Actually,” Twilight said, “I don't.”
“What?” Sunset shouted. “You didn't bring it?”
“No, I don't have it anymore,” Twilight said. “About two years ago my friends and I had to return the Elements to the Tree of Harmony to save Equestria from Discord's plunder seeds.”
Sunset sat back on her haunches, eyes wide and face pale. “You sacrificed the Elements? How are we supposed to protect Equestria without their power?”
“Sunset,” Twilight said, “what happened in the human world should have shown you that it's not always about power. We'll find another way.”
“I've already got guards watching the portal,” Cadence said. “I'll have them double it.”
“Alright. Either Twilight or I should be in the room at all times,” Sunset suggested. “We're the only ones who have experience with the human world.”
Spike cleared his throat loudly.
“Oh, and Spike, of course.”
“I am not leaving you alone with the portal, Sunset Shimmer,” Cadence said firmly.
Sunset rolled her eyes. “Set as many guards on me as you want, as long as they're watching the portal too.”
“We need to make a plan,” Twilight said. “If Shining Armor were here he could just put a shield around the portal so they couldn't get through, but that's not an option right now.”
“What's to plan?” Sunset asked. “We just throw any humans that come through right back into the portal.”
“I'm not comfortable with using force as our first means of defense,” Twilight answered with a frown. 
“So what, then?” Sunset asked incredulously. “Are you planning to make friends with them?”
“Ideally, yes. There's no reason to think we can't resolve this peacefully.”
Sunset shook her head. “Twilight, you're being naïve. These people are coming to conquer Equestria and take its magic power for themselves.”
“This is my kingdom,” Cadence said, “and I will not have it be the first to strike. We will defend ourselves if we have to, but only if we have to.”
Sunset threw her hooves up. “Fine. Talk to them, if you can, but don't say I didn't warn you.”
“That goes for you too, Sunset,” Cadence said sternly. “If I hear that you attacked the humans without provocation, you'll go right back into your cell.”
Sunset glared at Cadence, her lip curling angrily, but she nodded. “Yes, Your Highness,” she said stiffly.
“You two get to the portal,” Cadence said, “I'm going to speak with the guards. I can't watch it personally, but make sure that somepony comes to get me at once if anyone comes through.”
Twilight nodded. “Good luck, Cadence.”
“You too.” Cadence hugged her once more. “Now go.”

Twilight and Sunset, along with two dozen crystal pony guards, had been watching the portal for several hours without incident when there was a telltale ripple in the mirror. The guards stiffened to attention and Twilight and Sunset braced themselves as someone came through.
The first pony through the mirror was attempting to walk on two legs, but his new form was not suited to it. He stumbled and fell forward, cracking his head on the hard crystal floor. A long metal rod, which was attached to him by a strap that Twilight imagined would have been slung around his human shoulders, slipped off and skittered across the floor. Sunset immediately snatched it up in her magic and it glowed teal as she flung it across the room, far away from the pony. 
"What the—?!" The pony, who was dressed in a strange uniform of mottled green, blistered the air with a string of curses as he tried to get his new four-legged body to obey him. 
A few seconds later a second pony came through, quickly followed by ten more. Had the situation not been so deadly serious, it would almost have been comical watching them stumbling and falling over one another as they tried to function with their unfamiliar equine bodies. 
"What's going on?"
"It's a trap!"
"Fall back, fall back!"
"Everyone—" Twilight tried to say, but they did not notice her trying to speak. The uniformed ponies continued shouting curses and orders at one another, scrambling to get to their hooves and back through the portal.
"I may have forgotten to warn them about how their bodies would change," Sunset smirked. 
"Stop!" Twilight's magically enhanced voice boomed through the room. 
The uniformed ponies, about half of which had managed to stand by this point, scrambled together into something resembling a formation and faced her uncertainly. "Identify yourself!" one of them barked.
The crystal ponies surrounded Twilight protectively but did not make any hostile movements toward the uniformed ponies, who in all honesty did not appear to be much of a threat at the moment.
Twilight smiled as reassuringly as she could manage under the circumstances. "I am Princess Twilight Sparkle, and I don't mean you any harm." She turned to the nearest guard. "Go get Princess Cadence," she whispered. 
The guard bowed. "Yes, Your Highness."
Sunset stepped forward. "Put down your weapons!" she ordered. 
"Sunset," Twilight reproached her, "we are not approaching these ponies as enemies."
"See those metal tubes they're carrying?" Sunset asked. "They're called guns. They fire lead projectiles at hundreds of miles per hour. They could kill us all if we give them the chance."
Twilight blanched at the destructive force that Sunset was describing. No matter how small the projectile was, if it were traveling that quickly it would be deadly, not to mention that a soft metal like lead would expand on impact and leave a larger wound. It was a gruesome image. "Take the guns," she said quietly to the guards. The very word seemed to leave a bad taste in her mouth.
"Stand down," the one who seemed to lead the soldiers ordered the others. "We can't fight them like this."
The guards moved forward cautiously and took the weapons from the unresisting soldiers. 
"Alright, Princess," the leader said, "could you tell me exactly what's going on here?"
"I would like to know that myself." Everyone turned as Cadence entered the room, wings flared and eyes narrowed. "I am Princess Mi Amore Cadenza, Princess of the Crystal Empire, and I would like to know why you have come to my kingdom carrying such weapons."
"How many princesses does this place have?" one of the soldiers snickered. 
"Four," Sunset answered him. "There are four princesses in Equestria and you are in the presence of two of them. Now I suggest that you answer her question."
"Your country opened hostilities with us," the leader said. "Your people brought weapons to our land and endangered a school full of children."
Sunset winced as both princesses looked sidelong at her. 
"I am very sorry about what happened back then," Cadence said, "but I promise you that the attack did not have the consent of the Equestrian government. It was a single renegade, acting alone. In fact, it was Princess Twilight who put a stop to it."
"We have our orders, Ma'am," the leader said. "Equestria is an enemy of our country."
"Who gave those orders?" Twilight asked. "Could we speak with them? I think this is all a misunderstanding, and I know we would all prefer that it not come to bloodshed."
"Weren't you listening, Twilight?" Sunset asked. "He's as good as declared war on Equestria. I say we capture them. Some hostages should keep the others off our backs until the portal closes again."
"Sunset," Twilight said, "I know you have good reason to hate the humans after what they did to you, but that's too harsh."
"Harsh?" Sunset argued. "I'm offering a way out of this where no one gets hurt! We can send them back to the human world right before the portal closes, then we'll have another thirty moons to plan for the next attack."
"Let my men go," the leader of them said, "and I'll turn myself over to you. I won't resist."
"You would do that for your friends?" Cadence asked.
He nodded.
"I have another idea," Twilight said. Between his militaristic bearing and his willingness to put himself in danger to do his duty, this person reminded her a lot of Shining Armor. She got the feeling that she could trust him. "Take me to the human world with you. Let me meet with your people and show them that we don't have to be enemies."
"Are you sure about that?" Cadence asked. "It could be dangerous."
"He was willing to put himself in our power. As a show of good faith, I'll do the same." 
"Twilight, that's crazy," Sunset said. "You're a princess of Equestria. You can't risk yourself like that."
"That's precisely why I have to risk myself," Twilight said. "If I can take the risk instead of the ponies of this land, then it's my duty to do so. What do you say, sir?" she asked the leader of the soldiers. "Will you let me come with you to the human world?"
He frowned. "You're serious, aren't you?" he said. "You really want to walk right into enemy territory."
"I don't consider us to be enemies," Twilight replied, "and I want a chance to prove that."
"If that's really what you want, I can take you back with us."
"Take me too," Cadence said. "The Crystal Empire is my land, and my responsibility."
"You're insane, Sparkle," Sunset said, shaking her head. "Both of you are. Fine, I'm coming too," she said to everyone's surprise. "I know more about the human world than anypony."
"Me too!" Spike said. "Twilight would have been totally lost last time if I hadn't been there."
Cadence nodded. "That's a good idea. We'll send a delegation to the human world: two princesses and," she considered Sunset for a moment, "an ambassador, and of course we wouldn't leave you behind, Spike. May I have your name, sir?" she asked the soldier. 
"Sergeant Mighty Shield," he answered formally. After fidgeting with his foreleg for a moment he figured out how to make it do a passable salute, "and if you're sure about this, then I'll take you back with us." 
The three ponies and the baby dragon looked at one another. "We're sure."

Once again, Twilight found herself falling through a portal made of light. Her body stretched and warped strangely, forming long, skinny legs and arms and compressing her face into an almost perfect oval. She remembered the odd feeling of walking on two legs, but she thought that she had gotten pretty good at it by the end of her last time here, and thankfully she found that she had not lost the hang of it. When her feet hit the ground she was able to remain standing, and she quickly reached out to catch Cadence's arm as she came through. Sunset, of course, stepped through without so much as wobbling. She was more accustomed to her human body than her pony self by now. 
"What is this?" Cadence asked as she looked down at herself. Her skin had the same pink hue as her pony coat did, and a long mane of pink and purple hair tumbled down her back and one side of her face. She was wearing rich pink and golden clothing which, though well-made and bearing the symbol of her own cutie mark, felt very strange on her. She stared at her hands and realized that she could wiggle each of the strange appendages individually. She tried not to retch as she thought uncomfortably of fat pink worms growing from her hooves.
"It's alright, Cadence," Twilight said. "You're a human on this side of the portal. Your body will take some getting used to, and your magic won't work here, but you're still you inside. Just remember that, and everything will be okay."
While Twilight helped Cadence cope with the sudden change, Sunset approached Mighty Shield, who in this world was revealed as a strapping man in his mid-twenties. His uniform and equipment made a great deal more sense on his human body, and the gun that had been returned to him hung comfortably across his torso. Sunset had been vehemently against returning their weapons, but as Twilight pointed out, if the humans decided to fight then disarming these twelve wouldn't make much of a difference.
"So, Sergeant," Sunset folded her arms, "where to?"
Mighty Shield shook his head. "This is way beyond anything I'm authorized to handle. I'll have to take you to the captain."
Sunset nodded. She had figured as much. "Come on, you two!" she called to the princesses. Strangely, she felt much more in control here in this world, even though it had brought her some of the worst times of her life. "We've got one, or possibly two worlds to save!"
With a bit of help from Twilight, Cadence was able to avoid embarrassing herself as they walked to join Sunset and Mighty Shield. Around them were all the signs of an efficient and well-run military complex: drab but solid buildings surrounded them, vehicles roared past on important business, and groups of fit and trim men and women in uniform walked, jogged, or ran here and there. More than a few stopped to stare at the new arrivals and their escorts, but Mighty Shield and his soldiers led them through the complex unmolested. 
"What happened to the school?" Twilight asked, staring around with wide eyes. 
"It was torn down once they discovered the portal here," Sunset answered grimly. "The humans decided that it was too dangerous to have a school nearby and put this military base here instead."
"That's terrible!" Twilight gasped. The thought of tearing down a school to make room for... this... went against everything she believed in. 
"What would be terrible is leaving our children where they might be attacked again," Mighty Shield retorted. "If another monster comes through there like two years ago, we'll be ready to handle it."
"Well, Mr. Shield," Twilight said as they walked, "it might comfort you to know that the artifact that caused the attack last time is no longer in our possession." 
"Is that right?" Mighty Shield replied. "Why would you give up something like that?" 
"To protect Equestria," Twilight answered. "My friends and I found ourselves in a situation where the only way to protect our ponies was to sacrifice the Elements of Harmony. That crown was one of them. There is absolutely no chance of magic like that being brought into this world again."
"That's something that would be worth telling the captain," Shield advised them. "You'll probably end up going even higher up than him, but he's the ranking officer on base at the moment. 
"When do we get to meet him?" Cadence asked. 
"His office is right in here," Shield said, gesturing to one of the buildings. He led them in and through several drab gray hallways, finally stopping outside a door that looked quite a bit like all of the others. He knocked sharply on the door and waited for a reply.
"Come in," someone called from inside.
Shield opened the door and entered with the others a few steps behind him. He saluted sharply. "Captain Armor, sir!"
"Huh... buh... wha?" Twilight stammered. Cadence did not fare much better. Sitting behind the room's single desk was a large, well-built man with two-toned blue hair and a sharp red uniform crossed by a blue sash. 
Shining Armor's bright blue eyes widened as he saw who his sergeant had brought with him. "Twily?" he asked. "Cadence? What in the world are you two doing here?" 
"Um," Twilight said weakly, "it's a long story." 

The better part of an hour passed while Twilight and Cadence, with occasional help or clarification from Sunset and Spike, explained the situation. Shining Armor looked like he had a headache after the first five minutes. 
"So, are you Twilight and Cadence or aren't you?" he asked once they had finished. 
"They're another world's Twilight and Cadence," Sunset answered. "They probably have a lot in common with the Twilight and Cadence that you know, but they are their own people, just like you are not the same Shining Armor that they know." 
"Right." Shining ran his hands through his hair. "So where does this leave us?"
"As friends, I hope," Cadence answered him.
"Friends," he muttered, "right. You know that I have orders to find and capture the source of Equestria's magic, don't you?"
"I do," Twilight said, "but I also know that, if you are anything like the Shining Armor that I know, you're only obeying those orders because you believe that it's for a good cause."
"Protecting our country," he answered, "what better cause is there?"
"That's the thing, Shining," Cadence said, "you don't need to protect your land from us. I think our kingdoms might actually have a lot to offer each other."
"Look," Spike said, "if seeing these two here doesn't convince you that we aren't your enemies, what will?" 
"A talking dog," he grumbled. "I'm still not used to that."
"The portal is only open for three days every thirty moons," Twilight pleaded with him. "Do we really want to waste that time fighting? Just call off the attack." 
Shining rested his head in his hands for a long moment, then sighed. "Darnit, Twily, I never could say no to you."
Twilight's heart soared. "So you'll do it?" 
"I'll put in a formal report about everything you've told me," Shining said, "and I'll delay the attack until we get a response. That kind of thing doesn't usually happen in just three days."
"So the portal will be closed by the time you get the okay to do anything?" Cadence asked him.
"Yes, probably," Shining answered her. 
"Oh, thank you thank you thank you!" Twilight fairly leaped across the desk and hugged him. Only when he cleared his throat did she remember that, no matter how much they might resemble one another, this man was not her B.B.B.F.F. She stepped back, blushing fiercely.
Sunset frowned. "But this still leaves us with the problem of what happens the next time the portal opens. What if they decide to attack again?" 
"It seems to me," Cadence said thoughtfully, "that what we need is a go-between for our worlds. Somepony, or some human, to act as an intermediary and keep the peace." 
"That isn't very practical considering the portal's timeframe," Sunset pointed out. 
"Is there any way to keep the portal open, or to open it at will instead of waiting the full two and a half years?" Shining asked. "If there's a chance that we could be allies instead of enemies, that would be really helpful."
"Not that we know of," Twilight said, "but that doesn't mean it's impossible."
"Who would we use as the go-between, anyway?" Spike asked, bringing them back to the matter at hoof—or hand, as the case might be.
"We'll need someone who's familiar with both worlds," Twilight said. "Someone who knows both cultures and can smooth over any misunderstandings."
"Preferably someone who's used to being in charge," Cadence added. "Someone who's used to working both alone and with others. There will be a great deal to do." 
Twilight and Cadence locked eyes and smiled. Each already knew what the other was thinking. 
"I think I know just the one," Twilight said. She and Cadence both turned to look at the pony in question. "Who better than a former student of Friendship?"
"Me?" Sunset gasped. "But... but after everything I've done..."
"You said that you were beginning to make amends, Sunset Shimmer," Cadence said. "What better way than by promoting friendship between the two worlds you've called home?"
"Sunset," Twilight said seriously, "I don't want to force you into anything. I know that you've been through a lot here. I know that you've been... tortured." She almost whispered the word. "I really do think that you're the best one—maybe the only one—for the job, but I only want you to accept it if you're sure you'll be alright. If you have any doubts, Equestria will always welcome you home."
"Home," Sunset murmured. Her eyes brimmed with tears at the thought, and her heart glowed with the warmth of the friendship that Twilight was offering her. She didn't deserve any of it. She hastily wiped the tears away and faced Twilight tall and proud. 
"I'll be fine," she said. "I would be honored to act as our worlds' intermediary. Maybe next time the portal opens I'll be able to take you up on that offer."
"Oh, Sunset," Twilight cried. She threw her arms around Sunset and held her tight. "It won't be thirty moons this time, I promise. I'll work from Equestria, and you work from the human world. We'll figure out a way to open the portal, I'm sure of it."
Sunset stiffened instinctively, embarrassed by the affection, then relaxed into the hug and returned it. "I'd like that," she said with a smile. "I'd like that a lot."
"Ahem," Shining coughed. Twilight and Sunset sprang apart, faces red as they remembered where they were. "That's all great, but it's far from set in stone. There will be a lot of paperwork to do to get all of this in order. God, I hate paperwork," he groaned. 
"Yes, I know you do," Cadence giggled, "but you always get it done."
"Yeah, yeah," he mumbled. "Well, no time like the present." 

The remainder of the three days they had together was filled with a blizzard of activity and a mountain of papers. Twilight and Cadence, who weren't quite able to master using a pen with human hands, allowed Sunset to sign their names for them in the human world. Shining Armor was as good as his word, and the troops who had been ready to invade Equestria disarmed and stood down to await further orders. Some of the humans, meanwhile, were allowed into Equestria with Twilight and Cadence nearby to guide them in using their equine forms. They never stayed long, but many of them marveled openly at the beauty of the Crystal Empire and the magic of Equestria. In far too short a time they were all saying their goodbyes, but Twilight was determined to discover the secret of the mirror and how to open it at will. She swore that it would be much less than another two and a half years before they saw each other again. As the moon rose high into the sky on the third night, Twilight, Cadence, and Spike stepped through the portal for the last time. 
"Very well done, Twilight," Cadence said as the portal closed behind them. "Not only did you avert a war, you made a powerful new ally for Equestria."
"Thank you, Cadence, but I couldn't have done it without you and Sunset Shimmer."
Spike cleared his throat.
"And you too, Spike. Thank you for coming with us."
"Anytime, Twilight."
Twilight and Spike spent that night as guests in Cadence's palace and left for Ponyville in the morning. 

"Well howdy, Twilight! Howdy, Spike!" Applejack called out as she spotted them for the first time in days. "Where in tarnation have you two been?" The others were there as well, all clamoring to know where they had gone and what had happened. Twilight apologized profusely as she realized that she had effectively disappeared without a word to anypony, and she had been so busy the past few days that she hadn't even thought to send a letter. 
"So, come on already!" Rainbow said. "What have you two been up to?"
"Well," Twilight began, "it's kind of a long story."
Pinkie sprang forward. "The portal to the human world opened again and Sunset came through saying that Equestria was in trouble, but you went and talked to them and it all turned out to be a big misunderstanding, and now you and Sunset are trying to figure out how to keep the portal open so that our worlds can keep a connection and Sunset's going to be going back and forth between the worlds so we can all be friends! Right?"
Twilight and Spike stared openmouthed at her.