An idea I got from a dream. It's not exactly the most original idea ever, but I've done my best to make it an enjoyable read anyway. There is one OC created specifically for this story. Otherwise, I have kept to the canon portrayals of each character as closely as possible. Other than the OC, all characters belong and are copyright to the Sonic Team, Sega, etc. The OC belongs to me.
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Shadow stood, his arms crossed over his chest, just outside of the GUN Commander's office. It had been nearly half an hour since he was summoned, and he had no idea how much longer he would have to wait. Perhaps this would have been irritating for other people; he had spotted a few agents in the hallways casting him sympathetic glances as they walked by. He hadn't planned to do anything that morning, however, and he had far more time than most to spend. So he simply continued waiting, leaning against the wall next to the door.

"Um, excuse me," a timid voice spoke to his left. He looked up. A slim young woman, dressed as a secretary, was holding open the door to the office. "The Commander will see you now." Shadow straightened up and unfolded his arms, then headed through the doorway without another word. He noticed that the woman shied away to avoid touching him, inadvertently pushing the door wider. Once he had entered, she hurriedly closed the door after him and went to her desk. A tall, strongly-built man with graying hair was examining the world map against the far wall, hands clasped behind him.

"Shadow." The Commander spoke without turning around. "I've called you here because of reports I have received of…unusual circumstances." He reached one hand down and pressed a button. A spot on the map lit up and began pulsing slowly. "This is the independent province of Soleanna. I believe you have been there once before on a different mission." When the black hedgehog made no effort to answer, the Commander finally faced him. Vivid red eyes gazed calmly back at his mismatched ones, green and brown. "There have been people missing from Soleanna's New City. Shortly after their disappearances, my men began finding them scattered throughout Kingdom Valley, in various stages of insanity and catatonia. A few have been discovered dead. This has been going on for nearly a week, and we cannot find any explanation for it."

Shadow remained silent, still watching the Commander's eyes. The man blinked and shifted his gaze a fraction to one side. "This morning, some of my men in the area went missing. Therefore, I'm recalling all GUN forces investigating the matter."

"And you're sending me," Shadow surmised.

"Correct." The Commander folded his arms. "Kingdom Valley is a hazardous place; we have had injuries just from trying to navigate through it. I'm sure you have both the skill and the power to find what we couldn't."

"What is my mission?"

"Get into Kingdom Valley," the Commander ordered, meeting his eyes once again. "Find those that are missing and rescue them if possible. Most importantly, find out what is causing the disappearances and eliminate it." The black hedgehog looked past the man before him and found once more the flashing beacon that marked his destination.

"Understood."

Another half hour later, Shadow arrived at the temporary GUN base in Kingdom Valley. He would have made the entire trip on foot if he had to, of course, but the Commander had sent him in a chopper instead. After dropping off Shadow, the chopper would return to headquarters with what was left of the investigation. He didn't linger to see them off, instead heading straight into the ruin-dotted pass.

He had been there, once; he knew it as surely as he knew his mission, but he couldn't really remember it happening. Despite his lack of actual memories of the place, he was able to easily find a path through it, leaping over gaps among the fallen buildings and avoiding the often-hidden sudden drops to the river below them. He remained alert for any distress calls or signs of the Commander's missing men. Aside from the birds singing to one another and the roar of the river, however, he saw and heard nothing.

As he neared the end of the valley, approaching the point where one of Doctor Eggman's bases had a secret entrance, he finally heard it. A cry for help. He altered his course immediately and began searching for where it came from. Although it wasn't repeated, he quickly determined that it had originated from a spacious ancient courtyard situated next to the river, its pillars lying haphazardly among the wreck of its roof. No one was there.

Confused, Shadow conducted a more thorough search. He paused as he drew near the river, almost certain he had seen something odd under its surface. There. There it was again. A strange movement that didn't follow the current. He squinted at the object. Whatever it was, it appeared to be blue.

Blue?

Shadow rolled his eyes at the implications, then considered what to do next. He had heard the cry for help some minutes beforehand. If this blue thing was what he thought it was, that was plenty of time for it to have escaped the river. Yet there it was, still frantically flailing. He sighed and dove in.

Sure enough, Sonic the Hedgehog was at the river bottom, trying to jump or climb his way out. When he spotted Shadow, he waved his arms wildly. Luckily the river was not very deep. Shadow kicked his legs a few times, seized one white-gloved hand, then used the floor to push off and head back toward the surface. The current was strong, however, so by the time he dragged the blue hedgehog out of the water and dumped him on dry ground, they were a few meters downstream of where they had entered it. Shadow examined his wet gloves in distaste as Sonic stayed on his hands and knees, coughing.

"Thanks for the save, Shadow," he eventually said, sounding inappropriately cheerful given that he had just nearly drowned. Shadow glanced down at him, swiping water away from his eyes.

"You can't swim?"

"I know, funny isn't it?"

"I didn't say it was." He made to leave.

"Hey, don't be so cold." Sonic fell in next to him. "How 'bout we stick together?" He felt a brief surge of irritation as they both broke into a run, partly to move faster and partly to get to a sunnier location and start their clothes drying.

"Why are you here?"

"I was just taking a little walk and overheard some interesting things, that's all. People from New City that keep going missing. Thought it couldn't hurt to check it out, but I wasn't paying attention when that bridge gave out." Sonic performed a little flip as he came to a short gap between two stone beams, landing neatly on his feet on the other side and continuing running without pause. "Good thing you came by when you did, huh? What brought you here anyway?"

"Just don't get in my way," he warned, ignoring the question.

"Got it. I'll be sure to stay clear of your all-important mission from the Commander, since there's no other reason why you'd be somewhere like this. Or has that Eggman been talking to you again?"

Idly Shadow wondered how the GUN Commander couldn't drive him to impatience after half an hour, yet Sonic managed it in less than five minutes.

Accompanied by his unwanted and overly chatty companion, Shadow completed his search of Kingdom Valley without encountering anyone else, GUN or otherwise. The two of them took a short break at the remnants of a coliseum-like structure. Sonic explored the dilapidated-yet-impressive walls, apparently not understanding the meaning of "a short break." Shadow stood at its base, arms folded and eyes on the sky. He had completed only one of his three objectives, which was dissatisfying. He didn't know where else to look, though.

"Oi, Shadow!" Sonic called from above and behind him, interrupting his thoughts. He was tempted to ignore the other hedgehog, then realized that instead of sounding excited, Sonic had sounded startled. Wary, even.

"What is it?" he called back, turning to look. Sonic was standing at the very top of the coliseum's wall, looking down at something on the other side. He turned and beckoned for Shadow to follow, then leaped down over it. Shadow bent his knees and jumped, catching onto a row of short, thin pillars about halfway up. Easing his feet into the gaps between pillars, he jumped again, caught hold of the wall's upper lip, and vaulted over. He nearly landed on a black-clad figure slumped on the ground but twisted out of the way just in time.
He blinked to adjust to suddenly being in the shade and took a closer look.

There were five of them, all lying at the base of the wall and all with their eyes closed. The Commander's missing men. They were half armed; their pistols and knives were still in their holsters, but their rifles were missing. There were no signs of any kind of struggle. "Are they still alive?" Sonic asked. Shadow looked back at him. He was standing a little farther away, constantly shifting his weight from foot to foot.

"They're just unconscious," Shadow replied. "There's no hint as to why, or when they'll wake up."

"Oh, I'm sorry, that must have been my fault," an unfamiliar female voice said mournfully. Shadow spun around to search for the speaker. Sonic was doing likewise. "Looking for me?" it asked, now sounding mischievous. "Alright, I'll show myself to you." As it spoke the last few words, a pale gold shimmer distorted the air before them, and a slender figure stepped out of it. It resembled an abnormally thin human, androgynous, dressed in a long pale orange robe of some sort that completely obscured its hands and feet. The garment was layered and trailed behind it on the ground. A hood covered what should have been its head, but oddly, it was empty. The creature's face instead floated, white and mask-like, a few centimeters in front of it. The face was also androgynous, had red-orange eyes, and wore a pleasant smile.

Shadow distrusted it immediately. "What are you?" he demanded.

The face blinked at him. It was very strange seeing it move, as it was obviously not attached to any other part of the creature. "I am Neschume," it replied simply.
"What did you mean, they were your fault?" Sonic wanted to know, waving at the GUN soldiers.

Neschume didn't answer immediately. Its smile faded, to be replaced by a sorrowful expression. "I came from another planet, not too far from here, seeking new friends. It was so lonely, so very lonely at first, being all by myself in this beautiful new place...but then I found people who were willing to talk to me. They were quite good company, curious about what I was or where I came from." Its eyes twinkled as it smiled again, looking pleased and a little bashful. "Just as you two are now."

Shadow wasn't moved. "How long have you been here?"

Neschume batted its eyelashes at him coyly. "It's hard to say, you people here experience time so differently..."

"How about this then," Sonic suggested. "Could you tell us what happened to the friends you made?" At his question, the creature's smile disappeared. It seemed close to tears.
"They all went away." It wavered back and forth. "I brought them here to continue playing with me, but they all went away. People in black came and took them. They all went away." It sighed heavily and gazed at them. "Just like how everyone at home went away, eventually."

Shadow fixed Neschume with an inscrutable look. "Would you also say the men behind us went away?" he finally asked. It blinked.

"Why yes. They certainly aren't here." It tilted its head to one side, apparently confused. "Just try talking to them. Can't you see for yourself they're not here?'

"Then would you say the same thing if they were dead?"

Sonic glanced at him. "Shadow, you think...?"

"Yeah." The black hedgehog scowled. "This thing is what's been causing the incidents in Soleanna."

The alien smiled. "You catch on quickly." Its eyes narrowed. "I don't like that."

Something separated itself from its robe and shot toward Shadow. He flipped backward before it reached him, and it plowed into the floor where he had been. For a split second, both Shadow and Sonic saw a flat, pale orange appendage, extending from Neschume's robe at the shoulder. Then it withdrew from the ground and snaked sideways to attack Sonic. An indistinct blur flashed from his location to a spot on the other side of Shadow, slowing down to take on the blue hedgehog's form as he came out of his sudden acceleration.

"You're fast," the alien complimented them with some surprise. It had raised itself into the air, its robe transformed-save for the sleeves and hood-into a mass of thin strips, each with a sharply tapered end and each moving independently of the others. "This will be fun! Won't you play with me?"

Shadow settled into a defensive stance. Sonic grinned as he bounced from foot to foot, loosening up. "Sure," he answered for the both of them. "We'll play with you!"