Chapter Text

I. Chaos Theory

There wasn't a storm in Green Hill that day. In fact, it was a typical sunny afternoon. A gentle warm breeze ruffled the top of a nearby palm tree as the sun moved slowly across the clear blue sky. The closest thing to any dark cloud came from the figure standing on the hill overlooking the valley, who often seemed to bring one with him regardless of the actual weather.

Shadow the Hedgehog was very aware that was how he was usually perceived, particularly by the other residents of this zone. Not that it mattered. The opinions of the others were an irrelevance. All that concerned him was his duty, a promise made a lifetime ago to protect the world they called home. He was the Ultimate Lifeform and would carry out that mission by whatever means were necessary.

He stood, arms folded, staring down at the building below. Waiting. It had been several hours, but unlike his blue counterpart he had no issue with patience. Nevertheless, with no activity right now, his thoughts began to wander, contemplating as he had so many times before what compelled him to be here at all.

It had been a month since the 'incident' with the Paradox Prism. As far as everyone in this world was aware, it had been nothing out of the ordinary. Doctor Eggman had devised a scheme to grab another one of the seemingly endless set of magic rocks and ancient artefacts which apparently littered the planet. His plan, as usual, to use it to somehow take over the world. Sonic and the others had stepped in and things proceeded as always, with the good Doctor handily defeated and forced to flee. Shadow himself appearing to teleport the Prism away at the start of the fight was the only unusual event, but he was aware his mercurial nature meant they would most likely just shrug that off and move on.

He shifted his stance slightly, feeling the breeze blowing through his quills. There were of course two exceptions to 'everyone'. Sonic remembered what happened the first time they had fought Eggman in that cave, the shattering of the Prism and the worlds that were created. How close they had come to losing everything. So did he.

For everyone else, it had never happened. Timelines had reset, those worlds either never existed, or were now forever separated from their home with the return of the Prism. Sonic had simply moved on, treating it as just another adventure, likely to never be thought of or mentioned again. Shadow sometimes envied that ability. That being said, Sonic hadn't had to spend days drifting through a void, watching and powerless to take action while the reckless fool stumbled around trying to fix the mess he'd caused. Unable to see beyond the faces of his friends to the real people underneath and almost dooming them all.

Lost in thought, the black hedgehog wasn't aware he was also being watched until his unseen observer spoke.

"I've got bad news for you hun," came a voice from the branches of a nearby tree somewhere to his side, "I really don't think you're his type."

Shadow snapped out of his reverie, mildly annoyed to have been caught off guard.

"Hello Rouge," he responded gruffly, pointedly not turning to face her.

There was a fluttering of wings and the sound of feet landing in the nearby grass. "Come now," she said, with a slight pout as if offended by his greeting, "is that any way to greet an old friend?"

'Friend' was certainly a stretch, but Rouge knew that well enough. While he respected the bat for her expertise, 'occasional colleague' would likely have been a better description given their work together in the past. It also seemed unlikely this was a social visit.

"Did you want something," he asked curtly, "or are you just here to annoy me?"

"If I was planning to annoy you sweetheart, I'd have asked Sonic to come along," Rouge laughed, "he's much better at it than me."

That was undoubtedly true. However, unlike Sonic he didn't feel it necessary to vocalise every stray thought immediately. Waiting for an actual answer, he shot Rouge a sideways glance to make it clear she wasn't getting anything else from him without one.

"I've seen you a lot the last few weeks," she continued, "always close by, waiting and watching as if you're expecting something to happen." She looked at him with what appeared to be genuine concern. "I know standing and brooding is a big part of your whole deal, but this feels different somehow. Want to talk about it?"

Shadow fought back the urge to smirk. He had seen Rouge play this part far too many times and wasn't falling for this 'concerned friend' act for a second. Best to make it clear he had no intention of talking about this so she could leave him in peace. He shifted his gaze forward again, returning to his vigil.

"I am the guardian of this world," he responded flatly, "as such it is my duty to monitor anyone or anything that may pose a threat to it. How I choose to determine what that means is not your concern."

"Monitoring a threat," she said, "not exactly the response I was expecting."

Irritating. In his desire to draw this conversation to a swift end he'd let slip more than intended. Perhaps that had been her plan from the start, knowing full well he wouldn't fall for this 'friendship' nonsense.

"Not to say I don't understand, of course," Rouge continued, clearly intent on fishing for more information, "I expect you to keep an eye on Eggman, that's just common sense. Plus, I know you keep tabs on Sonic as you're convinced he's somehow an existential threat to the universe."

Shadow was grateful he wasn't looking at the bat, as even he hadn't been able to prevent his eye from twitching involuntarily at that particular remark. A pause though. Perhaps he hadn't been as inscrutable after all. Was this an opportunity to just turn and leave, bring this unwanted conversation to an end?

No. She was going somewhere with this line of thought. He also knew Rouge well enough to know she wasn't just going to drop this. Better to handle this now, rather than deal with the endless pestering until she got an answer which would satisfy her curiosity.

"I didn't hear a question," he prompted.

"Right. You've never paid that much attention to the rest of us though," she said, "which I've tried very hard not to take as a slight."

A glimmer of hope. Perhaps this was simply a matter of a bruised ego and this conversation could be over after all.

"I don't believe you would intentionally destroy the world," he said with a hint of sarcasm, "it contains too many shiny objects."

"An excellent point, it is certainly the place where I keep all of my favourite things. But then, it's not me you've been watching is it?"

That brief optimistic hope faded. Of course, Rouge wouldn't have spoken to him unless she was sure of her facts already. Truthfully, it hadn't been something he'd even been aware of at first, telling himself he was merely keeping tabs on Sonic's colourful friends, making sure there were no unforeseen after-effects from the shattering of the Paradox Prism. Somewhere along the line, he had realised there was a subconscious change in the way he looked at the others as a result of an experience they didn't even remember. Rouge was correct in one sense. There had been a time not so long ago when he had seen them as little more than part of Sonic's orbit. Each capable in their own way, certainly, but not any threat in their own right aside from their association with his rival. Then he'd seen first hand what they might actually be capable of, who they might become if any of them ever reached their full potential.

One of them in particular.

"So I have to wonder then," the bat asked, "why exactly have you spent so much time recently watching Tails?"

There was a long pause. His own words from a moment ago echoed in his mind. 'Anyone or anything that may pose a threat'.

After a few moments Shadow turned to face Rouge and fixed her with a steely glare. "I already told you."

He was absolutely not going to elaborate on that. He'd probably admitted too much already.

Time to go.

Ignoring her confused expression as he skated away down the opposite side of the hill from the workshop he had been staring at, his thoughts turned back to a conversation with Sonic the day after their return to Green Hill.

"Have you told them?"

"Huh?", came the surprised response. Sonic was laying on the grass with his head resting on one of the many trees in this part of the zone, and as usual not paying any attention to his surroundings. Despite it being early morning, it was already pleasantly warm. It never tended to get very cold in Green Hill. By the time he had spoken Shadow was just a couple of meters away, staring down sternly with arms folded.

"Have you told them?" Shadow repeated.

"Oh", said Sonic brightly, glancing over, "hi Shadow, long time no see."

Exasperating as always. "We saw each other yesterday."

"Right, the whole 'end of reality as we know it' thing," Sonic responded, snapping his fingers as if he'd only just remembered, "must've slipped my mind." He grinned in what Shadow could only describe as a very punchable way. More blatant attempts to irritate him.

"Stop avoiding the question," he said, striving to keep the annoyance out of his voice. Unsuccessfully, it would seem, given the small glint of amusement from Sonic. Fortunately, he didn't push it any further.

"Ugh, fine," Sonic said, "You're no fun, you know that?"

Shadow just continued to stare.

"There was the celebratory post-battle party after the cave, then old Egghead showed up in yet another mech to crash that, so we had to deal with that whole situation. Man, it was good to team up with the guys again." Sonic paused briefly, looking wistful, then continued. "By the time we sent Eggman packing we naturally had to have a second post-battle party. Then it was late, so I figured it could wait until tomorrow. Which," he mused, "is today now I guess."

"A simple 'no' would have sufficed."

"OK then," Sonic replied, before deepening his voice and trying to match Shadow's gruffer tone, "No."

Shadow felt his his eyes narrow. He did not sound like that. "So, you will tell them today?"

"I mean, sure," Sonic said, unconsciously rubbing the back of his neck. "Though, maybe tomorrow would be better, give everyone time to recover a little. Or maybe next week. Amy wants to have a movie night, apparently the new 'Casino Night Caper' film is going to be out, so the whole gang will be together."

"You're stalling."

"Me?" Sonic looked offended. "I don't stall. I am the fastest thing alive, stalling is, like, the opposite of my whole vibe. Plus, it's such a cool story. There are pirates, robots, wilderness adventures, dystopian nightmare cities." He grimaced. "OK, maybe that last one isn't much fun."

"They have no memories of the Shatterspaces?" Shadow asked.

"Nope," said Sonic, "I dropped a bunch of subtle hints and nothing".

Shadow raised an eyebrow.

"Hey, I can be subtle when I want," protested Sonic, "so far as any of them remember, we fought Eggman in the cave, you took the Prism and noped out and that was that."

"So?"

"So," Sonic said with a sigh, turning to look at the horizon, "do they ever need to know? I know it wasn't them, you made that very clear." He looked pointedly at Shadow, but then turned away again and continued. "I mean, if I tell them, will they feel guilty about it? Betraying their crew to chase after treasure, giving up their mind and body to act as enforcer for a cruel regime, and..." there was a very long pause, "... the rest", he finished, quietly.

Shadow also turned to face the horizon, deep in thought. He'd assumed Sonic would be desperate to tell his friends the story of his adventure and was not sure how to proceed. He chose his next words carefully.

"I will not tell them. They are your friends, you know them and how they will react. If you choose to carry the burden of those memories to protect them, I will respect that." He contemplated pointing out if he truly trusted them then it would not matter, but in his experience that level of trust was a pipe dream.

"Thanks Shadow," said Sonic, with unusual sincerity. He turned to look the black hedgehog again, brightening slightly. "No offence, but I wish there was someone else I could talk to about this."

Shadow scoffed and looked at him sideways. That feeling, at least, was entirely mutual.

After a moment, Sonic asked a simple question. "Would you tell them?"

"No."

It had been around an hour since his conversation with Rouge. Shadow was skating through the nearby valley, enjoying the sensation of the wind rushing by as he drifted rapidly between the palm trees, rocks and other small obstacles which made up the terrain of Green Hill. One thing he did share in common with the annoying blue hedgehog, he mused, was that running (or skating, he supposed) was a good way of clearing his mind and ordering his thoughts. The first of which was one of minor irritation at giving away even the small amount he had to the bat.

Gliding past a small lake, he caught a glimpse of his own reflection in the water, glaring back at him accusingly. 'Anyone or anything that may pose a threat' he had told her, something that would have been laughable only a few weeks ago. Sonic's friends were competent, certainly, but there was no world in which any of them would be capable of causing any serious harm or being a real danger to others. At least, that is what he had believed, right up to the point where he had seen a world where that exact thing had occurred.

A casual hop over a boulder, finding himself weaving along a rocky canyon floor, requiring slightly more concentration to avoid the debris from earlier rockslides. He knew, of course, this was unfair. After all, he had been the one to repeatedly remind Sonic these were not his friends and they could not and should not be treated as if they were.

A well timed duck into a slide though a narrow path under a large fallen rock. The canyon walls were narrower here. The red rock was different from washed out grey and brown, but nonetheless his mind drifted back to another crevasse much like this only a few short weeks ago. A constant battle against an endless army of robots, wondering just how long he could keep this up before finally succumbing to exhaustion. Compounded over and over again by the face of his tormentor appearing in the sky to taunt him for being too weak to stop him. That he should just give up and accept defeat. That he was only delaying his inevitable failure.

A sharp skid to a halt, path ahead blocked by a vertical cliff face. A dead end, both in this line of thinking and quite literally in the canyon itself.

The end had not come there, of course, though he hated to admit even to himself how close a call it had been. If it had not been for Sonic and the others proving to be enough of a distraction for him to finally escape, he wasn't sure how much longer even he could have continued the fight.

Bracing himself, he launched upwards and skated vertically up the side of the canyon, swiftly cresting the top of the wall before landing, half crouched on the ground and ready to take off once more. Another memory, this time of a similar landing at the top of a purple spire, the satisfaction of finally breaking the last of the machines that had been tormenting him for so long. A moment of catharsis he took no small pleasure in, cruelly and instantly ripped away by a sudden wracking pain, rendered helpless as he was hit by the raw energy from the Paradox Prism itself. Through a haze he could see that face again, twisted with fury and madness, blue eyes tinged purple from channelling the energy. He might be the Ultimate Lifeform, but this was pure, nigh-infinite power. There was no fighting this, nothing he could do, if Sonic hadn't finally seen sense and stopped holding back-

He forced his hands to unclench, barely aware he had balled them into fists. The breeze blew softly once again, the familiarity a comfort. A moment of quiet to collect his thoughts in the growing darkness, as the sun began to sink slowly below the horizon.

"No," he announced to the empty plain as the light continued to dim, "this is exactly what I told Sonic he must not do. I will not make the same mistake and blame them for actions that were not theirs."

A small brown lizard that was watching him from a nearby rock seemed unimpressed by this profound revelation, turning to scuttle away into the growing shadows.

He sighed heavily. There was something else which had been bothering him and it was certainly not helping with the goal of clearing his mind. Thoughtfully, he pulled out the Chaos Emerald he now carried.

It's green glow would typically have been a comfort in the encroaching gloom, but not for the first time since the fateful day he'd used it to teleport the Prism away something about it felt... wrong. He truly believed he was attuned to the Emeralds more strongly than any other being on the planet, but now it was as if the Emerald was troubled to be in his presence. He had resisted using it's power, instead simply keeping it safe and away from others who would misuse it. In truth though, he was concerned. The Emeralds were a part of this world. If it was somehow damaged or losing it's power, did that mean there was something deeper fundamentally wrong with, well, everything?

He was loathe to admit ever needing assistance, but this was too important for foolish pride. In other circumstances he might have sought a more scientific explanation. However, given the two foremost experts on the Emeralds were the fox he'd just described as potential threat to reality, and a mad doctor who absolutely was one, neither seemed a particularly palatable option. That left only one viable choice. If science would not provide the answer, perhaps another Emerald guardian could provide counsel.

He would speak to the echidna.