The Heart of Darkness

King Onyx raced south, toward the Crystal Mountains and the Quartz Pass. His new body was tireless, covering miles in minutes. The ponies of the city stared at the dark blur that flashed past them, but Onyx found that he did not care what thoughts lay behind those alarmed eyes. His every thought was bent on destroying the changeling invaders and reclaiming his empire. Had he ever thought to look behind him, he might have noticed the trail of blackened crystals he left in his wake, the land itself corrupted by the dark power seeping out of him.

        As the sun was setting, Onyx drew into sight of his army's encampment, roughly halfway between the Quartz Pass and the capital. The soldiers, preoccupied with their fighting retreat from the changelings, did not even notice the dark figure bearing down until Onyx was already among them. It was well for the ponies that they were not his target. Their shock was reflected in their eyes as Onyx soared overhead, his horn blazing green. Somehow, the glow pouring from his horn seemed to darken his surroundings rather than brighten them, as though it were drawing in and destroying the sunlight.

        The crystal king landed in front of the soldiers and unleashed his rage. Dark magic poured out in a wave, a flood, and those it touched fell to the ground in agony. Some changelings created shields in time to withstand Onyx's initial onslaught, and these gathered themselves for an attack only to be thrown aside and scattered by a dark crystal erupting from the ground. The crystal exploded into a million razor shards, shredding the already-battered creatures. In mere moments, the changelings -only a fraction of their army, but a sizable group nonetheless- had been overwhelmed and destroyed.

        Onyx turned. His crown shone in the light of the sun, no longer dimmed by the rush of dark magic. His soldiers' eyes widened as they saw that crown, then further as some were able to see past the increased size, the glowing eyes, and the jet-black flesh that had replaced his crystal hue. A murmur ran throughout the army as, one by one, the soldiers recognized their prince; their king.

        “Finish them.” Onyx growled. The ranks of soldiers parted before him as he left the battlefield, making for the camp. “Where is Diamond Ward?” he asked, as an afterthought, of nopony in particular.

        One of the soldiers pointed back toward the camp with a trembling hoof. Another tried to speak, had to clear her throat, then said, “General Diamond is resting, um… Your Highness. He has not had time to sleep in days.”

        Onyx nodded in acknowledgment and continued on his way. The soldiers he left behind looked to Captain Ruby, who had not said a word and whose normally rosy hue was looking rather pale.

        “Well,” the captain finally managed, “Your prince gave you an order. Dispatch those changelings.”

        Onyx reached the camp to find Diamond Ward already awake and ready to meet him. The general was flanked by five soldiers who were trying very hard to look as though they weren't guarding him from Onyx.

        “Onyx.” Diamond greeted him warily. “It is you, isn't it?”

        Onyx's green eyes flared. “You will bow before your king!” he hissed.

        “King? Onyx, what of your mother? What has happened to you?”

        “I have become strong, Diamond Ward. Strong enough to destroy the invaders.”

        “Onyx. Tell me what happened to Queen Crystal.” Diamond lowered his head slightly, pointing his horn toward the monster in front of him.

        Onyx's temper exploded. “You challenge me?! My mother is dead, you worm! I sacrificed all that I had, all that I was, to get the power I needed to lead my Empire.”

        “You killed her.” Diamond said quietly. “You've submitted to dark magic and murdered your own mother, our queen. Prince Onyx, you are a murderer and a traitor!” he scuffed the ground with his front hoof, issuing a challenge. “I hereby declare you an enemy of the Crystal Empire.”

        A low growl started in Onyx's throat. The sound grew with his rage, until it finally exploded in a roar of fury.

        “I am the Crystal Empire!” Onyx leaped toward Diamond Ward, his horn shining with deadly green power, only to be turned aside by a pulse of Diamond's magic. He landed off-balance and Diamond charged, his horn pointing toward Onyx's exposed flank. Onyx used his magic to raise a crystal with a deadly-sharp point directly under Diamond, thinking to end it with a surprise attack. The old general, however, was a crafty fighter and still quick on his hooves. Diamond dodged to the side and continued his charge all but uninterrupted. His horn pierced Onyx's side, driving in deep toward the vital organs.

        The other soldiers in the camp milled in confusion. Their general had declared this pony an enemy, but too many recognized him as Prince Onyx, which meant that his authority superseded that of the general. Who should they obey?

        Onyx bellowed in pain and rage, but the wound -which should have been fatal- did not stop him. Diamond, realizing too late that he had over-committed to his attack, tried to dart backwards but fetched up against a crystal that had not been there a moment ago.

        Onyx reached out with his magic and seized the general. Diamond fought back, but could not overcome Onyx's sheer magical strength. “Soldiers!” he shouted, “Attack! Atta-!” his words cut off with a gurgle as crystal spires shot from the ground, piercing him from every direction.

        The light slowly faded from Diamond Ward's eyes, but he kept his gaze fixed on Onyx. His horn glowed blue as he tried to summon one more attack, but he did not have the strength. Diamond slumped but could not fall, pinned as he was by the crystals. He lifted his head one last time and looked Onyx in the eye.

        “Onyx…”

        Diamond Ward's head fell forward, and he moved no more.

        Onyx gazed around at the other soldiers. His eyes blazed with furious green energy. “Does anypony else name me traitor?” he growled. “Bow before your king.”

        The soldiers of the Crystal Empire dropped to their knees and bowed their heads. “Long live King Onyx!” they said in unison.

        Unseen by the soldiers, Onyx blinked and shook his head slightly. Somewhere within that chorus, he could have sworn he heard Diamond Ward whispering his name.

        The soldiers returning from the changeling slaughter looked grim despite their victory; nopony was comfortable with Onyx's orders that the changelings be killed when they were already beaten. Their expressions went from unease to utter horror as they saw what sat in the center of camp: Diamond Ward, still suspended from the black crystals that had ended his life, his translucent blood pooled on the ground beneath him.

        “What is this?!” Captain Ruby demanded upon arriving at the scene. The soldiers shuffled uncomfortably, and none spoke up. “Somepony tell me what happened here. That is an order!”

        “Diamond Ward attacked his rightful king.” a voice rasped from the shadows cast by the crystals. Onyx stepped out into the light and faced the captain. “He was executed as a traitor. My congratulations, Ruby; it seems you've been promoted to General.”

        “I… I… yes, King Onyx.” Ruby bowed, and so did not notice Onyx flinch at the sound of his name.

         “…Good.” Onyx said after a moment. “Then let us end this war.”

        With Onyx's immense power leading them, and the changelings weakening day by day without the energies of the Crystal Heart to feed upon, it took mere days for the crystal ponies to sweep the enemy army back to the mouth of the Quartz Pass.

        “The war is all but won, Highness.” General Ruby reported. “It is just a matter of pushing them through the Pass and out the other side of the Crystal Mountains, and then they'll be beyond our territory. We will set an outpost on the far side of the Pass to ensure that no enemies can come through there again.”

        “Not good enough.” Onyx growled, staring at the map in front of him, “There.” he gestured with his horn to a small path that led deeper into the pass. Too narrow for an army, but enough for a small group to get behind the enemy. It was a gambit he had considered once when the Empire was desperately defending against the invaders; now he would use it to annihilate them. “Ruby, send a contingent through there. We'll trap them.”

        Ruby swallowed nervously. She feared to speak against this new Onyx, but… “Your Highness, is that necessary? More of our ponies will die. We could continue pushing the changelings back with minimal losses.”

        A low rumble came from Onyx's chest, and his eyes bored into hers.

        “Y… Yes, Your Highness. I will give the orders at once.” Cursing herself for a coward, tears of remorse and frustration stinging her eyes but firmly kept from falling, Ruby galloped away to make the arrangements.

        The ragged remnants of the changeling army stood in the Quartz Pass to make their last stand. It was a good position for them, or so they thought: the army of the Crystal Empire might have been depleted by the war, but it now outnumbered the changelings. The mouth of the pass would force the crystal ponies into a narrow line, allowing relatively few at a time to reach the battle. It was entirely possible, Ruby thought, that she had been wrong. The changelings might have held out after all. That is, they might have held out were it not for Onyx's magic. Were it not for the ambush that would spell death for every single changeling left in the Crystal Empire, and a fair portion of the crystal army as well.

        Onyx himself stood on a small rise to oversee the battle. He was surrounded by six ponies: two unicorns, two pegasi, and two earth ponies. The soldiers had been hoof-picked by Ruby to serve as Onyx's royal guard, as though he needed them. Ruby was not certain that the king was even mortal any longer.

        Ruby checked the position of the sun -it was just beginning to set behind the highest peaks. The time had come. “The Crystal Army will advance at a walk!” she ordered. The pony next to her raised his flugalhorn and blew a quick series of notes, relaying the order to the rest of the army. Once battle was joined, her troops hidden in the mountains would descend to hit the changelings from behind, trapping them in a fatal pincer.

        A faint hissing and buzzing echoed from out of the canyon as the changelings set themselves for combat. The front lines of the Crystal Army were halfway through the canyon, perhaps half a mile now separating them from their foes.

        “The Crystal Army will advance at a trot!” Ruby shouted. Her herald, Amethyst Watch, blew the appropriate signal and the crystal ponies quickened their pace, jogging flank by flank toward the killing ground. Ruby narrowed her eyes. She had to wait for just the right moment, soon enough to give her troops the needed momentum, late enough that they did not wear themselves out. Steady… steady…

        “The Crystal Army will charge!”

        Amethyst blew a series of sharp notes followed by a single long one, drawn out for as long as his breath could sustain it. The crystal ponies' ranks stretched slightly as they ran full-tilt toward their foes, horns ready to gore and hooves to kick and trample. They hit the front lines of changelings with a crash that was audible even as far back as Ruby stood. Any moment now, her soldiers would pour down the sides of the pass and the battle would begin in earnest.

        “Where are they?” Ruby demanded. The foals should have attacked by now.

        “General!” Amethyst shouted in alarm, “Look!”

        Following his outstretched hoof, she saw chaos in her ranks. Crystal ponies had suddenly turned to attack each other, their neighbors not noticing their peril until too late. What was going on? And where is my second wave?!

An earth-shaking roar of surprise and rage caused Ruby to whirl around. The six soldiers Ruby had set to guard Onyx had gone mad all at once, and were attacking the king with hooves, horns, and magic. Onyx staggered as one of the earth ponies bucked and slammed his hind legs full-force into the king's head, then gasped as a unicorn's horn pierced his side. A bewildered Ruby half-expected to see Discord, the chaotic spirit who ruled the lands to the south, laughing hysterically as he played havoc with their lives. No, that isn't it. The simple, obvious truth hit her like a stallion's kick: changelings. The Crystal Army had been infiltrated.

        “The Crystal Army will fall back!” Ruby yelled in a panic. She had to get her ponies out of there, regroup, try to salvage this disaster.

        Amythest blew on his flugalhorn, desperately sounding the retreat. “What of the second group, General?” he asked between blasts.

        “Dead, I'm sure.” Ruby said, not letting herself feel the pain of that statement; not yet. There was still a chance to save the rest of her soldiers.

        “General, should we not assist the king?”

        Ruby looked back to see Onyx still beset by the six impostors. She wasn't certain that she wanted to help him; wasn't certain that she should. Might it not be better for this demon to fall here, and not return to rule the Empire?

        The decision was taken out of her hooves as spiky dark crystals erupted from the ground all around Onyx. His attackers' disguises failed as they were run through by the king's attack. Six changelings, revealed for what they were, fell dead to the ground.

        The Crystal Army, however, was routed. Panicked ponies trying desperately to escape the changelings were running away with no thought to formation or defense. Some, braver or more foalish than the rest, stood their ground to protect their friends and were quickly dispatched.

        General Ruby galloped toward the hill where Onyx stood surrounded by the bodies of his attackers. “Your Highness!” she shouted, “We have to get-agh!” She looked in disbelief at the black shard piercing her stomach.

        Ruby was lifted off the ground as the spire she was impaled on continued to grow. She raised her head and looked with pleading eyes at Onyx. Blood poured from her mouth as she opened it to ask, “Why?”

        Onyx barely spared a glance for his failed general -his second failed general- as he strode toward the disaster that this battle had become. He did not see her watching him accusingly, did not hear the choked gurgling as her lungs filled with her own blood. The dark power was surging through him again; all he could see was the promise of victory, all he could hear was its call to conquest.

        Onyx passed through the back ranks of his troops as though they did not exist. Even caught in their blind terror, the soldiers parted to make way for him. Hemmed in as they were by the narrow canyon, the changelings had no escape from his wrath.

        The king bellowed his challenge. Crystals erupted from the floor and walls of the canyon, killing changelings by the dozen. Changelings who had been preparing to meet Onyx in combat found themselves pinned to walls or suspended helplessly in the air as their lives drained away. Those who tried to fly were caught as the crystal shot ever higher up the walls.

        Freed from the threat behind them, the soldiers turned to face the changelings who were still harrying them from within their own ranks. With no formation or plan, it quickly degenerated into a frenzied melee. Ponies lashed out at those changelings who had dropped their disguises, while others attacked their friends and comrades, thinking them impostors. Onyx turned from the enemies in front of him to face those behind, but was as helpless as the others to tell changeling from crystal pony. His eyes narrowed as he considered the situation; the dark magic singing in his blood, however, allowed only one solution.

        Spattered horn to hoof in blood and changeling ichor, Onyx left the Quartz Pass. He had accomplished his mission: not a single changeling who had entered the Crystal Empire had escaped his wrath. The entrance to the Pass was choked with bodies, and Onyx, who had sent the full might of his army to face the invaders, returned from the battlefield alone.