Author's note: this story takes place in an AU. More specifically, in a world where Shadow had taken the Hero Side of the Pure Evil path on the game Shadow the Hedgehog.
"Graaaah! Shadow…do not think this is over." Shadow the Hedgehog smirked as he landed, having just finished off Black Doom. His journey had brought him here to the last stronghold of the G.U.N. forces. After journeying with Rouge in this base and retrieving the chaos emerald, Black Doom had appeared, ready to kill him for 'disobeying.' Now, after a final strike, he had been knocked to the ground, gasping for air.
The red Chaos Emerald fell from his clutches and floated down gently to Shadow. Raising his hand, Shadow grabbed the emerald before taking a stance of victory along with Rouge, who was all too happy to have brought down Black Doom. With him down, the Black Arms forces would fall. G.U.N. and earth would still have a chance to see a brighter day. "We did it!" she thought to herself.
"Sorry to disappoint, but this is the end!" declared Shadow, regaining his composure. Taking out all of his chaos emeralds, he let them fly up into the air, with all of them slowly coming back down to him. Making a whistle that constantly changed pitches, the seven chaos emeralds, the jewels containing power unlike any other, soon arrived beside Shadow and began swirling around him slowly as the black hedgehog admired them. Red. Blue. Cyan. Green. Purple. Yellow. Silver. All seven at long last were now in his grasp. His past meant nothing now; Shadow knew who he was. "Finally…I've got ALL the chaos emeralds."
"Shadow!" growled Black Doom, panting where he lay. "This isn't over yet! The Black Arms will rise again." he stated, trying to get up but ultimately failing. Rouge smirked; they had him right where they wanted him. Now all that was left was to finish him off, then she and Shadow could get to work on facing the rest of his army.
"I'm Shadow the Hedgehog. The ultimate life form born to rule all!" proclaimed Shadow, raising his hands to his chest and tightening them into fists. Immediately, Rouge turned to Shadow, eyes widened in terror. Upon closer inspection, he did seem a bit darker. Anger, rage and hate now lingered in his voice, unable to be ignored as if it were an awful stench in the air. Eyes locked in a heartless glare, fists locked tightly and the seven chaos emeralds revolving around him, Shadow had the look of a soon-to-be dictator. Letting his arms drop slightly, Shadow continued. "With the power of these emeralds, I'm going to conquer the universe!" he announced, raising an open hand into the air and shutting it in one swift motion. "This is who I am!" After that, he began to laugh. Laugh and laugh both manically and psychotically.
"What!" asked Rouge, taking a step back in fright and apprehension. She dreaded what would come next. No one could defeat anyone who exercised the power of the seven chaos emeralds. Not G.U.N., not Eggman, not Knuckles, not even—
"Hold up, Shadow!" It all happened in a second. Shadow, Rouge and Black Doom all looked to the east side of the room, only to see a blue blur ram Shadow full force into a wall, sending the emeralds flying everywhere. All of them hit the ground with soft thuds, yet they continued to glow luminously. A grunt of pain came as Shadow began pushing himself from the wall. Only one emerald remained in his hand; the red one. Growling, Shadow looked up. The other six emeralds were gone.
"What!" Suddenly, a hard punch came from Shadow's left, knocking the ultimate life form into the ground. Whatever that was, it had incredible speed. It had to be—
"Sonic!" cried Rouge. Sure enough, as Shadow looked up, there he was; Sonic the Hedgehog, the fastest thing alive, standing in front of Shadow, looking down at him with a fierce expression instead of his usual excited grin. That always annoyed Shadow, but now, things were getting fun. He even had the emeralds with him as well, suspended in midair all around him. How kind.
"Sonic. What a surprise." Shadow said coolly, standing up with a small smirk. "How rude of you to interrupt me."
"Don't even start," Sonic warned, taking a battle stance. "I saw what you've been doing. Why'd you do it, Shadow? That's what I wanna know." A cold chuckle was his only response.
"Does it even matter why I did it?" he asked, "It doesn't matter why. I did it. I helped Black Doom take down these worthless humans and now look at him." Turning his head, Sonic looked to the dark lord, who was still on the ground in pain. Shadow did that? After all he had done to help the Black Arms?
"…Why?" was all Sonic could ask. In all honesty, he dreaded the answer.
"Why? Because, Sonic, I wasn't going to let him conquer this planet. I'm going to conquer this planet and the rest of the universe afterwards." Fury like no other began to erupt within the blue hedgehog like a volcanic explosion. If Shadow thought he was going to rule anything while he was around, the so-called "ultimate life form" was delusional!
"Fat chance. I ain't lettin' ya, Shadow." retorted Sonic. Shadow didn't speak for a few brief seconds. Tension levels were enormous, felt by everyone in the room. There was nothing but absolute certainty that they would combat each other.
"Very well then." Shadow eventually replied. "Chaos…control!" Time froze. Nothing moved or even breathed. All was still. Everyone was statues except for Shadow. More chuckling came from the hedgehog as he calmly walked over to Sonic. "Idiot." Carefully, he began to retake the emeralds.
When time began moving again, Sonic was shocked. Shadow had vanished! "Wha? Where did he go?" Sonic asked, looking around quickly.
"Sonic!" called Rouge. Turning instantly, Sonic gasped as he saw Shadow, surrounded by all seven chaos emeralds, standing atop the lifeless corpse of Black Doom.
"S-Shadow! Stop, wait!" The emeralds began flying around Shadow, moving faster and faster, glowing brighter and brighter. Before he could react, a blinding explosion of energy and light shot out from Shadow. Sonic looked away, knowing all too well what was coming next. As the light faded, Shadow had transformed, his fur now glowing a radiant gold instead of being its regular black. Super Shadow.
Instantly, Sonic and Super Shadow sped off into a hall, rocketing by many G.U.N. soldiers and Black Arms fighting each other, shooting rapidly with their selected guns. As the speeding hedgehog and super hedgehog passed by, the forces stopped their firing and turned to look in the direction they went. Both hedgehogs were accelerating rapidly, hitting 200 miles per hour easily and becoming blue and yellow blurs. 300. 400. 500. No limit seemed possible for them. 600. 700. They were now breaking the speed of sound, skillfully maneuvering through the base with ease.
Smirk turning into an evil grin, Shadow shot forward with a burst of speed, easily passing by Sonic faster than the blue blur could blink. The next thing Sonic knew, he had been blasted hard by one of Shadow's chaos spears, the energy being enough to make him lose his balance and trip. Seeing the opportune moment, Shadow halted instantly and held his fist out.
"CRASH!" Sonic's head made direct contact with the fist, crushing his skull inwards. His body, now shaking slightly, fell limp to the ground, lifeless. Silence filled the air, as if the world was taking in the death of Mobius' greatest hero. Soldiers, Black Arms and humans alike, began rushing into the large and spacious room that Sonic had died in. Sandbags and vehicles were spread all across the concrete floor. Steel walls surrounded them, the occasional G.U.N. logo sprayed on them. As more and more soldiers entered, the room became quieter and quieter. The stillness that followed was one of the most unnerving there had ever been.
"S-Sonic?" came the voice of Amy Rose, who was also there along with Tails and Knuckles.
"Sonic!" cried Tails, tearing up.
"S-Sonic!" exclaimed Knuckles, his breathing quickening from the shock. "Gohhhh! What'd you go and do that for, Shadow!" Knuckles asked, growling and waving his fist as if he were going to fight him.
Shadow did not answer. There was no need to. No, the only thing left was to crush the last of the resistance. All of which, were located here. Bursting with laughter, Shadow began powering up, a firey aura shooting out from his fur. This was the end. The end for G.U.N. The end for Sonic's friends. The end for the world.
1 week later, a broadcast went out across the world on every frequency, every channel, everything that could receive a signal was receiving the broadcast.
"Attention, people of earth. This is your new ruler, Shadow the Hedgehog. I'm announcing my takeover of the planet, and any who try to resist shall be obliterated."