Nightmare Moon sat regally on the throne as she stared out at the gathered nobles, arrived at her summons, and those non-noble petitioners who had the courage to bring their petitions before the Nightmare Throne. She was actually rather pleasantly surprised at the sheer number of petitioners, all with genuine petitions according to the Noctus Guard, a group of bat winged pegasi who had been training in secret for generations to enter her service upon her return. In her private chambers, she had squealed happily to discover that her new kingdom came with loyal minions(1).
Despite the noble's protests, Nightmare Moon had proclaimed she would address any truly urgent petitions from the commoners before addressing the nobles. When one of the nobles - a Duke Wellington, she believed - complained about it too vociferously, she cast a spell at him that turned him into a boot. She had intended a newt, but his name threw her off. She'd then levitated the boot to beside her throne and proclaimed she would hit in the head with it the next pony to question her directives.
In order to speed things up a bit, she had ordered her Noctus Guard to find out what all the petitions were ahead of time, and then group the petitioners based on the nature of their petition, rather than the order in which they arrived. That way she could address numerous petitions of similar type in one go, rather than having to give the same answer over...and over...and over again. She wasn't sure why this led to Celestia smacking herself in the face with one hoof, but she found that delightful.
The first group of petitioners approached. "Please, Your Majesty," they begged, "we are but simple farmers. Our crops are our livelihood. Without the sun, they will all die. Please...bring back the sun."
Nightmare Moon snorted derisively. "Do you take me for a foal?" she asked. "Do you think my desire is to rule a frozen kingdom of death? Have you not noticed the Moon still follows its normal path, despite the absence of the sun?" At the confused response, she continued. "I have positioned the Moon in front of the sun(2), where it is absorbing the sun's light and converting it into enhanced moonlight, which shines down and feeds plants as surely as the sun did. The 'day' cycle is now when the Moon is visible, and is slightly cooler than normal, whereas the 'night' cycle is when the moon is not visible, and is slightly warmer than normal. The average annual temperature is still constant, so there need be no concern regarding an ice age, either." This was addressed to the group directly behind the farmers, the climatologists.
"But what about the gravitational effects on ocean currents of a continuous alignment between planet, moon, and sun?" one of the climatologists - who, oddly enough, had a surfboard cutie mark - called out.
"I've already run the calculations," Nightmare Moon explained. "The oceans themselves are naturally magically charged, and the life inside them will adapt easily. Also, all coastline communities are already adjusted to take even the highest and lowest tides into account, and the total effect it will have on those communities: a continuous Proxigean Spring Tide." She smirked. "I imagine the waves will be...choice." That got a laugh from the other scientists in the group and a blush from the vocal one.
The next group of petitioners came forward...and their spokespony looked rather embarrassed. "Umm...we came to find out what happened to Princess Celestia," she admitted.
Nightmare Moon chuckled. "Care to answer that yourself?" she asked, looking up.
Celestia smiled down at the mare. "Thank you for your concern, my little ponies. Aside from my imprisonment, I am quite well. Nightmare Moon, much to my surprise, appears to be a rather considerate and thoughtful kidnapper and tyrant."
Nightmare Moon shrugged. "I learned from the best," she murmured, remembering those times she'd taken a day off from participating in games to play cards with Princess Peach and Bowser while waiting for the player to get Mario to the last castle.
"Enough!" somepony shouted from amongst the nobles. As the stallion approached, Nightmare Moon frowned. Cadence had briefed her on this one quite thoroughly. Prince Blueblood. "Do you think you can just march in here, imprison our ruler, take over our government and our kingdom, and no one will lift a hoof to stop you?"
"It looks like I just did that," Nightmare Moon replied. "What's your point?"
Blueblood stomped his hoof, charging up his magic. "You think I'm afraid of you? I will strike you down where you stand! I am Prince Blueblood, nephew to Princess Celestia! Who do you think you are?" He charged forward, his charge practically a picture out of a storybook. In point of fact, Nightmare Moon could see he'd practiced charging until he'd found a way to do it that would make his mane flow in the breeze of his passage without getting mussed.
Sneering, her billowing mane shot forward, wrapping around his neck and horn and lifting him into the air. "I am Nightmare Moon," she stated calmly. "Queen of the Night. Ruler of Nightmares. Tamer of Demons. Dread Champion. Tyrant. Despot. I have reclaimed my birthright within this kingdom, reigning over it as I should. You are a pathetic, spoiled, selfish, sniveling, noble brat. When was the last time you have had an unselfish thought in your head? When was the last time you felt charity in your heart? When did you last have a kind word for someone that didn't have an ulterior motive?" She brought him close to her face. "...if I snapped your neck right now...who would grieve?"
Celestia gasped a bit as she heard this, but could do nothing.
Nightmare turned, glancing over the gathered nobles and commoners. "Well?" she asked. "My question was not just for this pompous ass. Is there any here who would beg for his life? Who have reason beyond petty selfishness or ambition...to plead for my clemency?"
She waited silently for a response.
In the desert west of Appleoosa - where cooperation with the buffalo as the Eternal Night continued had helped farm and ponies to thrive - Twilight and the others confronted a giant sandworm that had been crafted as the guardian of the Element of Honesty. Towards the end of the fight, Applejack was consumed...only for the sandworm to turn to stone. The rocks then swirled around as it fell apart, revealing Applejack. The Element of Honesty hung around her neck, the gold choker decorated with rolling hills. The earth itself bowed to her will as her power grew.
Nightmare Moon almost felt sorry for Prince Blueblood. As she stood there, awaiting somepony to plead for his life, she was greeted by silence, shuffled hooves, and averted gazes. She watched his face fall as he realized that none could give non-selfish reason why he should live.
Before she could act, however, one stallion stepped forward and bowed. "If I may speak, your majesty?" he asked politely, his voice cultured and urbane.
Nightmare Moon blinked. His appearance and behavior rang a bell based on what Cadence had told her, but... "Your name, stallion?"
He rose back to his hooves. "Fancy Pants, Your Majesty."
Nightmare Moon's eyebrows rose. Cadence had described Fancy Pants as one of the few nobles with more in his head than fluff and more in his heart than ambition and greed. "You would plead for clemency on his behalf, Sir Fancy Pants?" she asked curiously.
"I would indeed beg you spare his life, Your Majesty," Fancy Pants continued. "But not for his sake. For yours."
Murmurs of shock and wonder spread through the assembled. Celestia also looked flabbergasted. Nightmare Moon, however, narrowed her eyes. "Explain."
Fancy Pants nodded. "Your Majesty, what he said is true. You have conquered us, and assumed full tyrannical authority. However, as you have stated, you have taken pains to make sure your seizure of power has not disrupted the kingdom, keeping all things running smoothly and living. You may well be a conquering tyrant...but you have not brought destruction or despair to Equestria. While your way of taking power was questionable, your reign has not been stained by terror or murder." He jerked his head towards Blueblood. "And he is not worth changing that."
Nightmare Moon examined Fancy Pants for a time, considering his words. "It seems there are some nobles in this day and age who are still worthy of the title," she murmured. She turned back to Blueblood. "Prince Blueblood, with the full authority of the Equestrian Throne, I hereby strip you of lands, title, and claim to nobility. You are no longer a Prince...but a common citizen. That is your fate now...to struggle to live your life, without royal assistance, without the pampered comfort you have grown accustomed to...and the knowledge that none here would stand up for you for your sake. Begone from my sight...and learn from this."
As Blueblood was dragged from the throne room, Celestia let out a breath she hadn't realized she was holding. For a moment, she had been terrified Nightmare Moon would actually go through with her threat...and she would lose Luna forever. She made a mental note that when/if things returned to normal, she think of some appropriate reward she could give Fancy Pants.
"Sir Fancy Pants," Nightmare Moon stated. "I offer you the lands, titles, and responsibilities of the Prince of Equestria, the head of the Noble Council. Do you accept?"
Or Nightmare Moon could beat me to it, Celestia thought ruefully.
Fancy Pants blinked in surprise, then smiled ruefully. "If it's alright, Your Majesty, I would like to decline. I feel I'm at the limit of my capabilities with what I'm already responsible for. I do not feel I would make a good Prince, nor do I desire the authority."
Nightmare Moon stared at him for a time. "All I have learned of statecraft tells me your very statement makes you the best candidate...but I respect your choice. It shall be held in trust until you and Fleur have produced an heir you feel is up to the task. In the meantime, choose what nobles you feel care more for the country than their own ambitions to form the new noble council, to advise me in my rule." She then turned to the rest of the hall. "For those of you not on that list...think carefully before you enter this Throne Room again. Ask yourself if the petition you bring is worth your life if it displeases me."
It wasn't long after that when the only one in the Throne Room besides Nightmare Moon, Celestia, and the Noctus Guard was Fancy Pants. Nightmare Moon then leaned towards Fancy Pants. "I would consider it a personal favor if you made sure the bit about my rule not being that bad didn't spread as far as the adventuring heroes. It would be so disappointing if, after all this, they chose not to fight me."
Fancy Pants let out a chuckle. "Consider it done, Your Majesty." Turning, he left the throne room.
Celestia watched Nightmare Moon in confusion. She...wanted to fight the Element Bearers? She did make a comment about them being 'too weak' to fight her. Was she trying to make them stronger? What else was she doing to assist them?
Rainbow rolled her eyes. "Twi, just don't look a gift hydra in the mouth."
"But...but it doesn't make any sense!" Twilight complained. "These...travelling merchants...have shown up ahead of us three times! That...that doesn't make any sense! How do they keep getting ahead of us?"
"Oh, we have our ways," Flim replied.
"The call of money is a siren song that brings us hither and yon, or yon and hither!" Flam agreed.
"And that's another thing!" Twilight shouted out. "How come all these nightmarish creatures we keep fighting against - which somehow strengthen Fluttershy and Applejack's Element abilities when we fight them - keep bursting into huge piles of gold bits?"
"You really need to play more video games, Twi," Rainbow grumbled.
Pinkie suddenly started twitching. "Oh...that one's going to be a real doozy whenever it happens!"
Nightmare Moon organized her paperwork. "Next petition?" she asked.
The doors of the throne room burst open, and an assault vehicle only she would recognize as a tank - though one made of wood and nails rather than the metal she was used to - rolled to a halt a few feet from the throne. The cockpit popped open.
"CUTIE MARK CRUSADERS NIGHTMARE SLAYERS, YAY!"
Nightmare Moon stared at the three fillies that had climbed out to face her. "...adorable," she said at last. "Tell me children, do your parents know where you are?"
Scootaloo glared up at her. "My parents are agents of the Crown! They'd be proud of me for following in their hoofsteps by restoring Princess Celestia to her rightful throne!"
"Mah Granny's having trouble with her bad hip cause of the colder temperatures," Apple Bloom declared, "mah big brother's struggling to keep the farm going in the night, and mah big sister is helping hunt down the Elements of Harmony ta stop you!"
"My parents told me to have fun storming the castle!" Sweetie Belle piped up happily.
Nightmare Moon gave a chuckle. "Alright, children," she said indulgently. "Take your best shot."
In the Crystal Mountains north of Manehatten, deep in an unmarked volcano, Twilight and her friends confronted a massive Salamander - a reptile of living, magical flames - that guarded the Element of Laughter. Part way through the battle, Pinkie pulled out a grenade, pulled the pin, and leapt into the creature's mouth. When the grenade went off, the Salamander burst into confetti...and Pinkie Pie reformed from living fire, the Element of Laughter - gold choker decorated in writhing flames that changed pattern every time someone looked at it - around her neck.
Nightmare Moon stared around at the end result of the Cutie Mark Crusaders' attempt to slay her. She herself was unharmed - not because she had shielded herself, but because no bit of the artillery actually came near her. The cage around Celestia had deflected anything that would have hit her. However, every inch of the Throne Room save the Nightmare Throne was in ruins.
"...well...the place was a bit out of date, anyway..." Celestia murmured ruefully.
"I had been planning on redecorating to reflect my nature," Nightmare Moon added. "The bright gold really clashed with the dark obsidian of the throne." She tilted her head as she saw the fillies glancing at their flanks.
"Dag nabbit!" Apple Bloom pouted. "Still no Cutie Marks!"
"And I was so sure this time..." Scootaloo added sadly.
"But wouldn't Nightmare Slaying be a really specific Cutie Mark, anyway?" Sweetie Belle asked. "Are there even any others besides Nightmare Moon?"
Nightmare Moon chuckled. "Is this the normal outcome of your attempts at earning your Cutie Marks?" she asked them.
"Yeah," Apple Bloom replied, looking around at the devestation.
"Pretty much," Scootaloo added.
"Sometimes it's worse!" Sweetie offered helpfully.
Nightmare Moon laughed gaily. "How wondrous! Hmm...perhaps you three might consider working for me, instead?"
The three fillies scratched their heads for a bit, then huddled. After a time, they leapt into the air, shouting, "CUTIE MARK CRUSADERS NIGHTMARE SOLDIERS, YAY!"
In the statue gardens of Canterlot Castle, Discord started shoring up the cracks in his stone prison, just to be on the safe side.
(1) She still had no idea why the Noctus Captain - an otherwise fully capable and reliable officer - screamed "BANANA!" at the top of his voice at random intervals. She decided not to do anything about it, however, because she found it hilarious.
(2) Luna's transformation to Nightmare Moon - as revealed in "Princess Twilight Sparkle" in the flashback - occurs as Luna moves the moon to create a solar eclipse. That makes a great deal more sense to me than locking the sun on the opposite side of the world.