A warrior's regret

"Celestia! Everypony is supposed to gather at the castle grounds! Hurry up, this is important!" The light blue unicorn said as she was putting on the gold and orange armor of the imperial army.
Celestia hurried away from her book, and started combing her long, purple hair. She then quickly put on her armor as well, remembering to put on her medals. It was required of her to wear the medals at every meeting since she became captain.

"This better be important. This is supposed to be my break," Celestia muttered before placing the helmet on her head.
"Luna, could you put my bookmark on my book before we go?" Celestia asked. Luna nodded, and set the bookmark at the correct page. "Let's go," Luna said as they ran out the door.

***

"Soldiers! Prepare yourself! We are at war!" The yellow alicorn roared.
"A group of ponies calling themselves 'The midnight republic,' have foolishly turned against me. Their leaders told me unless I would step down and rule by democracy, they would attack. Of course, I stood against them.

"However, even though we are superior in numbers, we musn't get overconfident. The midnight republic has magic I have never seen before. This may be on the same level as the 'Crystal empire' incident, possibly even worse. That is why I can't afford any spies in my troops.
"Those who will foolishly fight with the republic, feel free to go now. I don't want anypony who isn't completely loyal to me to show themselves in my ranks. Go fight with them if you so desire, but know that the Solar Empire will strike you down without mercy," Emperor Solaris said.

His amber eyes scanned his army from the balcony he stood at, as if looking for a reaction.

When he put his gaze on somepony, they turned away, as if meeting his eyes would have them executed. Celestia, however, looked straight back at him, her pink eyes meeting his amber hues. Suddenly, many guards started leaving. Celestia scoffed. Fools. Did they really think they had a chance? The republic was too small to stand a chance against the imperial army. They would be effortlessly slaughtered. Then she saw that Luna was one of them.

"Luna, what are you doing? Come back!"
Celestia said as she tried to stand in her sister's way.

"I am going to join the republic. Come with me, sister. We both know that the emperor is corrupt. This is our best chance to overthrow him,"
Luna answered, looking deep into Celestia's eyes.

"I won't. Luna, there is no way the republic will win! Stay with me, sister, stop this madness!"
Celestia begged.

Luna's fair face was grimacing with anger and betrayal.

"You are only saying that because you want to rule Equestria! Don't lie to me, sister. I have seen how you hunger for power.
Ever since you became captain, you have only talked to me about how you plan to become Solaris’ heir. The only reason you are staying is so you may be given the gift of immortality! I will not recognize myself with some hypocrite!" Luna shouted.

When she didn't get a reaction, she turned away from her sister, and joined the other guards who were going to the republic, leaving a shocked and devastated Celesta behind.

"I see some ponies are not loyal to me. Take a close look at them, soldiers. These are the ponies you will be fighting in the future. Do not show them mercy. They may be friends, or even family, but now they are enemies of the empire.
And enemies of the empire is to be destroyed. Stay strong together, you who have proved yourself loyal.
For the Solar empire!" Emperor Solaris roared with pride.

"For the Solar empire!" The imperial army shouted back, excluding a lonely Celestia.

***

The headquarters of The midnight republic was located in a dark cave, barely illuminated by firefly lamps, that gave a cold and eerie light. Luna couldn't see the faces of her comrades, but she could feel that they were scared. She couldn't help feeling afraid as well. Without her armor, she felt exposed. She had gotten rid of it after she had packed her things from her room so that she wouldn't be seen as a threath to the republic.

Then, out from the shadows, a pegasus mare emerged.
"Tell me you names, ranks and intentions, please,"
she requested harshly.
"Luna Moonfall, sergeant, asking permission to join your ranks,"
Luna replied.
"Sword Strike, private, asking permission to join your ranks," a young stallion said.
One after one, they told they wanted to be in the republic's army. The harsh expression of the pegasus mare softened, and turned into a gentle smile.
"Well, that can easily be arranged. Follow me, please."

The ponies followed her quietly, making sure to stay close. Eventually, they reached the end of the hallway. A closed wooden door stood in front of them.
"stay here," the pegasus said as she opened the door and walked in.
The former guards waited in silence. They could have been statues the way they stood, waiting for the pegasus to return.

Eventually, the door opened.

"You can come in now," the pegasus said from behind the door.

They nervously walked in. An earth pony mare sat behind a wooden desk covered in what looked like important paperwork.
Luna couldn’t quite distinguish what color the mare’s coat was, but in the dim light it looked pale yellow.

"So, you want to join our cause?" the earth pony asked. She looked at the ponies in front of her, as if measuring them up. "Well then. Let’s get started, shall we?"

***

"Are you sure this will be neccesary?"
The bearded stallion asked.
"I'm sure, Star Swirl. My sister has grown very powerful since she joined the republic. I am the strongest in the imperial army, and even I'm not sure I can defeat her on my own if she keeps getting stronger like this, and asking the emperor to defeat her is out of the question," Celestia replied.
"How powerful is she, exactly? I won't let you use the elements unless it is absolutely neccesary. Using them on her just because you aren't sure of your own abilities would be a waste of their powers,"
Star Swirl asked.
"She broke through the protective enchantments that were placed to protect Ponyville with only one spell before destroying the village in seconds, nearly wiping out the whole population. The only survivors were fillies, colts, and the Apple family. She didn't even hesitate to kill the mayor.
If worst comes to worst, I want some of the mages here to use the elements on her,"
Celestia answered.
"I see. We will be ready to use them, but only if it seems neccesary," Star Swirl said.

***

"Sister, please! I don't want to fight you," Celestia pleaded.

"You are no longer my sister, Celestia. You made your choice when you decided to stay with the Solar Empire, and I made mine. My loyalty lies with the midnight republic now. Not you. Even if we are related," Luna replied.

Luna's fur had grown darker since last time they had seen each other. Instead of the light blue she used to have, it was black. Her mane and tail had also changed into dark purple. Her appearance was beautiful, stunning even, but you could tell she was dangerous by looking into her eyes. They had become ice blue. Seeing into them made Celestia uneasy, like if Luna was staring into her soul.

"So be it then. But killing me won't change anything. Your republic is on the losing side, Luna." Celestia caught her spear in her magic, ready to fight, similarly as Luna held her sword.

"Shut up!" Luna yelled, charging at Celestia, furiously swinging her sword, while Celestia blocked with her spear before she pushed Luna back with her shield.
Channeling magic into her spear, Celestia sent powerful beams of energy towards Luna, who desperately tried to avoid them. The beams were leaving huge craters in the ground, making the field look like a wasteland. Luna answered the attack by sending magical spears at Celestia. But Celestia conjured a powerful shield, which absorbed the spears' magical power, and sent it right back at Luna.

In the nick of time she conjured a shield, though it barely had any effect. The blast sent big pieces of her light blue armor through the air as she fell to the ground. The only part of her armor left was her helmet, the shoes and her chestplate, with a silver crescent moon in the center. Somehow, Luna still managed to stand up.

"Huh. So you're still alive. I guess you really have become stronger since last time. That was supposed to be the killing blow. Still, you are nothing compared to me.
Give up, dear sister, and perhaps the emperor will spare you. What do you think will happen to the members of The midnight republic once the empire wins? Emperor Solaris has already sceduled the executions of your inner circle and the honored guards, such as you. The rest will be servants of nobility. Do you really want that to happen to you? I want my sister beside me again," Celestia said.

"Your empire is corrupt, only favoring the rich. The Midnight republic will change things for the good of Equestria. A world where one pony reigns supremely over the rest is not a world I want to live in," Luna replied.

"And I won't lose to a blood traitor and a hypocrite like you!" Black smoke started spiraling out of Luna's horn, swiftly covering her body.

She could feel her body changing. Her eyes changed, starting to resemble a predator's, her legs were getting longer, her mane changed until it resembled the night sky. As she ended her spell, she felt something on her sides. She spread her wings, her transformation complete.

Celestia, shocked by her sister's new appearance, stood in awe. The only alicorns she had seen in her life were emperor Solaris and empress Umbra.
"H-how? That's impossible! How were you able to ascend? There's nopony who would ever pass it into you!"
Celestia shouted in surprise.

"The republic has revealed the secret to ascension. Before they tried it out themselves, I volenteered to be a test subject. You see, they modified the enchantment to not only giving alicorn status, but they added a companion spirit to help the new alicorn in every way while giving more magical power. They told me to activate the enchantment only when neccesary. And this is just the right moment," Luna explained.

"Interesting. Perhaps I should look into that after I defeat you," Celestia said. "Keep in mind though, dear sister, that even if you manage to kill me, it won't save your children."

Luna's fair face twisted into a grimace of pure hate as she charged at Celestia. Holding her sister into a magical grip, she roared in fury.

"WHAT HAVE YOU DONE TO MY CHILDREN? WHAT SECRETS HAVE YOU TOLD?"

Celestia made a smug grin.

"Oh, I needn't gossip. After all, it would be a shame to let slip who their father is,"
she replied. Five ponies in wizard robes revealed themselves, each of them holding a glowing gemstone.
As Luna was distracted, Celestia teleported to them, and held up a gem shaped as a star. The six gemstones started glowing brighter, a small rainbow connecting them as they spun in a sircle.
As Luna stood in awe, the star shaped gem floated in front of the five who were still spinning. The five spinning gems seemed to give the star shaped one power.

"Goodbye, sister," Celestia said before a beam of light struck Luna.
Luna felt her body split apart, but it didn't feel like dying. It felt like teleportation. She couldn't move as she felt her particles be sent away from Equestria. As she felt like she was coming back together again, she started to feel sleepy. Unable to fight it, she drifted away into unconciousness.

***

"I should congratulate you, Celestina Moonfall. Thanks to you, we defeated The Midnight republic sooner than expected. You are no doubt the most honorary of my soldiers. That is why I wanted to see you personally. Do you want some tea?" Emperor Solaris asked.

"Tea would be nice," Celestia replied. She knew what she had to do.
Solaris's strongest soldiers always dissapeared when he asked them for tea. Celestia followed, keeping her wings hidden under her armor. She had found the secret of ascension in the cellar of the republic. The emperor would soon be dead.

They sat at a small table with two mugs of tea, cookies and sugarlumps. She put two sugarlumps in her mug, and pretended to wait for the tea to cool down. In reality, she waited for a distraction to switch the mugs. She was sure it was poisoned.

A knock on the door got Solaris' attention for long enough for Celestia to switch the mugs. She smiled to herself. Things were going smoothly. "Not now, I am dealing with important business here," Solaris answered. "Now, you and me have a lot to talk about.»

Soon, both Solaris and Umbra would be dead.
"Now, let's drink this delicious tea. For the Solar empire,"
Solaris exclaimed.
"For the Solar empire," Celestia replied.