Author's note: Happy New Year! Another thank you to E-Rank and CVGWJames for their continued feedback!

Chapter 3: Best-kept Secrets

The ground rumbled beneath his feet, with the surrounding hills shifting endlessly in the Marble Gardens. Sonic enjoyed the added challenge, of course, jumping across giant mud pits, looping around unstable hillsides, and spindashing over the occasional loose boulder that conveniently tried to block his path.

He had made the mistake once of asking Tails why this zone seemed to be plagued with constant earthquakes when, technically, there wasn't a ton of earth beneath the floating island to cause it. Three days later, the little fox had flown to Angel Island and spoken with Knuckles (read: harassed) until it was determined that some dilapidated tunnels of Hidden Palace were beneath the Marble Gardens, and the instability was most likely caused by the underground area's saturated Chaos energy levels.

Regardless, Sonic learned very quickly not to test Tails' knowledge on, well, anything after that, lest he enjoy the subsequent fallout and frazzled research for days on end. Additionally, he had made the smart decision to chalk up all phenomena to Chaos, when other more scientific theories fell flat.

There was the sound of a motor behind him, causing the hedgehog to glance back at his dark doppelganger. His rockets were especially loud on the rocky terrain, and probably a little harder to control since the ground was not very level. Shadow seemed unfazed, however, easily leaping the breaks in land and deftly skating (running?) around the larger obstacles.

Stopping atop a larger hill, Shadow pulled up aside him smoothly, his rocket shoes turning off as instantly as they had fired up.

"I figure we can split up here," Sonic suggested. "You wrap around the borders, and I'll check out the underground zones."

"Underground?"

"Er, yeah. You know, Lava Reef, Hidden Palace..?" An involuntary flinch escaped when Sonic added, "Hydrocity?"

"You do not like water," the black hedgehog said.

"What makes you think there's any water?"

"Etymology." Shadow paused. "And your reaction."

Sonic's spines bristled at his astuteness, never mind the condescension he surely heard in the tone. He kept a neutral face when he replied, "I can handle it."

His rival crossed his arms. "You do not wish me to see the home of the Master Emerald."

It was a statement, not a question, and a painfully true one at that. "What? No," Sonic debated, then hesitated. Eventually he shrugged. "It's not really me, per se…"

The perpetual scowl of his acquaintance only deepened. Sonic sighed. "Knuckles is pretty protective of the Sacred Grounds and, if he catches you down there—"

"Versus catching me up here?"

Ugh. This guy was annoying. "…Fair point," Sonic finally said. "Maybe we'll just stick together, then." Giving each of his ankles a roll of the joints, he smarmily added, "You better keep up, though!"

Just as he was about to zoom off, Shadow's rocket skates roared to life and he bent forward.

"You mean you better keep up with me."

In a flash of propulsion he was gone. Sonic's smirk only widened, however, and he jetted off after him.

He caught up with the supposed Ultimate Lifeform in a few seconds, but admittedly had to put on the speed to do so.

He purposely and dramatically yawned as he paced himself beside Shadow. Even if he was pushing a little harder than usual, Sonic certainly wasn't going to show it.

Shadow did not say anything, but his body bent forward more, his stance not unlike a speed skater. With it, his position moved ahead just slightly, gaining velocity.

"Hey, Shads!"

"Stop using that—"

"You might want to jump!"

Eyes instantly back on his surroundings, Shadow let out a colorful expletive before he went through, rather than over, a bunch of ridiculously large mushrooms. Sonic let out a barking laugh, jumping on the tops of his own set of fungi in order to catapult himself to higher ground.

Bursting through some dense foliage from below, Shadow reappeared next to him a few moments later, bits of greenery still sticking out of his quills. Shooting a pretty scathing look at Sonic, the black hedgehog spindashed mid-run, sending lodged bark, mushroom, and shrubbery firing out like the shrapnel of a grenade.

"Whoa!"

Sonic's arm barely made it up in time to block a projectile aimed conveniently at his face. He shot his own perturbed glance at Shadow before pushing his speed faster.

They deliberately wove through much of the zone, covering as many angles as possible, before Sonic led the way down to Hydrocity. The hero opted to stay close to the upper levels of the underground reservoir, now with a much keener understanding of what tunnels to take to avoid the flooded canals below. Knuckles had a few control stations for the complex that he would frequently visit, which Sonic generally avoided like the plague, namely because of their close vicinity to huge amounts of gushing water.

He dutifully inspected each post, however, because he promised Tails he would actually look for the Guardian, even though he had a sinking gut feeling that his friend was nowhere on this island.

Shadow was relatively quiet in the underground watering hole, his rocket shoes still working flawlessly on the slick floors. Just how did he power those things, anyways? He certainly made it seem like some sort of Jedi mind-trick, though with Chaos energy he supposed—

His thoughts crashed when Shadow slammed on his brakes, Sonic's crazy-fast perception not fast enough to take into account that he himself had just thought about the slick floors.

That mattered a lot, in fact, because they were near a control station along the middle levels of the Hydrocity tunnels. There, you could program timed release of valves, to allow some of the higher pipes to release their built-up pressure into the reservoir below.

Which, of course, happened to be this precise instant, because Sonic always seemed to have impeccable timing when it came to his favorite liquid.

The waterfall came from an opening above, a deluge that flowed straight down and over the old bridge the two hedgehogs had been traversing. The irony of it all, however, was that Sonic's instinct to panic didn't even have a chance to kick in. One moment he was turning to see Shadow's shoes squeaking on the mossy wooden crossing, and the next he was a drowned rat, complete with a faceplant.

He spluttered and coughed, though the sheer force of the drenching was enough to keep him from accidentally trying to breathe in any water. As he pulled himself to his feet, he dared a glance back at the hedgehog accompanying him.

Shadow stood motionless, arms crossed in front of him and the smallest—tiniest—smirk pulling up one corner of his mouth.

"Not. A. Word."

Spinning in place to get most of the water off, Sonic didn't wait around to hear, much less see, Shadow's reaction. He took off and picked up on the rocket sounds a split second later, but opted to keep his sights on his surroundings ahead, especially where the pipes opened up.

He was never going to live that one down.

The rest of the search went (obviously) speedily and (thankfully) uneventfully. They came back up to the surface, looping around the mountains and briefly into the known parts of Sandopolis before heading up into Ice Cap zone. Rounding through the hillsides brought them into Lava Reef, and—after more hesitation on Sonic's part—he finally led the two through the secret entrance and down into Hidden Palace. Its labyrinth of jewel-encrusted passageways snaked underground near the base of the lone mountain range centered on Angel Island, and at its pinnacle was another shrine, albeit this one was empty.

With a sizeable amount of pride literally and figuratively washed away, Sonic still stayed a few paces ahead of Shadow throughout the trek, the latter keeping relatively mum during the search, as well as the consequential tour of the ancient echidna ruins.

Hyper-aware of his environment, despite there not being even a drop of water nearby, Sonic instantly saw Shadow slow to a second fast stop near the palace's shrine, the hero slamming his shoes into the floor a millisecond later.

"Why did you stop?" he asked with a lot more anxiety than he intended.

"It was here."

"Wh—"

"Negative energy," Shadow interrupted, glaring at the floor. "It was used here."

"Negative?" Sonic asked, taking a few steps towards the area.

"It is not Chaos energy."

"I don't feel anything." Sonic walked a half-circle around the black hedgehog, waiting for whatever it was that Shadow apparently felt. A thought came to him and he stopped. "Wait. Are you saying Knuckles was here, when..?"

"Something happened here," Shadow vaguely insisted.

Sonic rolled his eyes. "Thanks, Sherlock."

"Who is Sherlock?"

He opened his mouth to retort, but snapped it shut with a mild groan. "He's clearly not here."

"No."

"And I don't feel whatever this negative energy is, either."

"You are not attuned to Chaos."

"Uh." Sonic put his hands on his waist and tapped his foot for emphasis. "I beg to differ, Shads."

Shadow's perpetual glare soured further, if that was possible. "If you were, you'd recognize the difference."

"What difference?!" he exclaimed, looping around the black hedgehog in a blink. "There is nothing here."

No response.

"I know what negative energy feels like," Sonic asserted, "and it isn't here."

Shadow's expression changed minutely as he eyed him. "I am not referring to dark Chaos energy."

"Then you're not making any sense," Sonic growled. "If it's not Chaos energy, then what is it, and why do I have to be 'attuned to Chaos'"—his voice became purposely croaky as he air-quoted and exaggeratedly mimicked Shadow—"to feel it?!"

The dark hedgehog stayed silent.

With a frustrated sound Sonic threw his arms up into the air and paced more circles around the tunnel. "You know what there is a lot of nothing from?—is you. You couldn't be more indirect about what's going on here than Cubot in a corn maze!"

"I have told you what I know."

"Right," Sonic sarcastically shot back. "G.U.N. had an emerald-finder from Eggman, you stole it and had Rouge retrieve the Chaos Emerald before they could, but now she's missing." He shook his head. "Since when?"

"Since when what?"

"How long has she been missing?"

Shadow let out a breath. "One day."

Sonic scoffed knowingly and crossed his arms in defiance. "So you're telling me that she's been gone one day and you suddenly knew she was taken?"

Silence.

"Rouge, the jewel-lover of Mobius, was given a Chaos Emerald and told to find another, and you're worried that she hasn't returned."

His rival's eyes settled darkly on him, and did not ease up. "Do not question her loyalty."

"Okay, fine. Can I question your gullibility, then?"

That got him an outright growl. "I can just take the Chaos Emerald and leave."

The blue hedgehog stood up a little straighter, keeping his arms crossed despite the tension building in his muscles. "Tails' emerald? Uh, no, you can't."

"I chose not to."

"Ha! You mean I stopped you," Sonic argued easily, "just like I'll keep stopping you."

Shadow took an aggressive step forward, the two hedgehogs dangerously face-to-face. His hands were in tight fists at his sides. "Try me."

Sonic found himself with teeth clenched, staring down his rival and contemplating his next move. Shadow hadn't budged, but appeared to be about one twitch away from attacking.

He could take him. Especially without a Chaos Emerald in his possession.

The cocky brooder deserved it. It would be easy.

Okay, well, maybe not easy. But probable. Sonic's slow, scrutinizing breath came in through his nose, Shadow's own breathing equally controlled. Both were ready to fight.

What, exactly, would any of this prove, though?

Rouge was gone. Knuckles was gone. The Master Emerald was broken, the rest of the Chaos Emeralds nowhere to be found. Sonic's shoulders slowly eased down from their taut state, and he forcibly relaxed his jaw. With a small puff of air (and maybe just a slightly facetious grin), the hero took a small step back.

"Look," he started neutrally, "I'm not doing this with you. It's clear that something is going on here, and … we need to work together on this."

It was a poorly worded truce, but one nonetheless. Seconds of uncertainty ticked by before Shadow gave a curt nod, his own stance defusing before he finally turned away, towards the area of supposed negative energy.

Sonic watched his change in demeanor carefully. "We should get back," he said. Shadow nodded once again, still taking in the scene around him. He was disturbed by whatever it was that he was feeling, that much was obvious.

But what was it?

With a rustle of grass, the two hedgehogs stopped at the shrine of the Master Emerald, wherein the giant green gem was still very much cracked, trails of pure Chaos energy leaking into the air like effervescent smoke.

The Tornado was in sight down the hillside, a speck in the horizon more or less, but from it to the emerald there was no sign of Sonic's sidekick.

A surge of worry wound its way up. "Tails?" Sonic called, zipping around the immediate area. He cupped his hands around his muzzle and raised his voice. "Tails!"

Shadow hadn't moved, his eyes doing the searching that Sonic's impatient feet were.

After a few panicked bursts of speed around the gem, he stopped in front of Shadow. "Dang it! I knew this would happen!" He pointed accusingly at the broken bauble.

"He is—"

"It's like its got a giant 'TOUCH ME' sign on it, right? And I leave the nosy brainiac with no control over Chaos energy, never mind an ounce of self-preservation, alone to study it—"

"Sonic?"

"Don't you 'Sonic' me, I—!" the hedgehog yelled, his voice having risen with each subsequent sentence of his tirade. He glowered at Shadow, mouth open to yell further, when he saw that the black hedgehog had a questioning brow raised at him, his two-tailed kid brother beside him and the one that had spoken. The fox had his Miles Electric and was staring at the hero like he'd grown a second head.

"Tails!"

"You didn't find Knuckles, I'm guessing?" the fox asked, even as Sonic zipped up to him and gave him a short but fierce hug.

"He is not on the island," Shadow confirmed.

"And why were you freaking out?" Tails asked Sonic directly, who opted to clear his throat awkwardly as he stepped to the side. The fox's eyes narrowed when he deadpanned, "You thought I touched it, didn't you."

Sonic's hand absently went up to scratch an ear. "…It is shiny."

"Thanks for the vote of confidence." Tails shook his head and walked around the blue hedgehog, back up to the Master Emerald.

"It's Shadow's fault!" Sonic hurriedly accused, following his sidekick. "He kept going on and on about negative energy."

"Negative energy?"

"I dunno. Shadow said he felt it in Hidden Palace, but I never did." Sonic glanced over, seeing that their reluctant companion was following them slowly, his attention glued to the shrine's shattered prize.

"What is negative energy, though?"

"It does not come from Chaos," Shadow inputted.

"So another energy field?" Tails asked rhetorically while humming. "I wonder if it's what caused this," he added, pointing at the Master Emerald with his emphasized word.

"No," Shadow answered, "but I believe this energy is linked to what happened to the Guardian." He paused. "And Rouge."

Sonic felt his jaw agape, downright appalled at how easily he answered Tails. He snapped it shut and nonchalantly gazed elsewhere when Shadow must've felt his stare and looked his way.

"Huh," Tails responded, oblivious to everything else as he digested that information. His focus remained on his handheld computer, a frown forming as his fingers typed in a slew of commands. There was a familiar concentration on his expression, Sonic noted, as he most likely tried to put together puzzle pieces faster than Sonic could ever hope to run. He apparently came up empty-handed, however, because he finally looked at both Sonic and Shadow disappointedly.

"Well, I'm not getting anywhere," the kit complained. "My readings are all out of whack from the overwhelming amount of Chaos energy emitting from here." A loud sigh escaped. "I could probably find this new energy's wavelength—whatever it is—but not with all this concentrated Chaos skewing my data." He gave the large green stone a rightful scowl, but with another smaller sigh his eyes went back to Sonic, worry evident in their shine. "I was hoping you'd have more success."

The hero came up to Tails, his arm wrapping around his shoulders encouragingly. "Don't worry, bud, we'll find Knux."

"You said you had found all the emeralds."

Both Tails and Sonic slowly turned to the third speaker. Tails hesitated before replying, "Had being the operative word, yes…"

Shadow stepped towards them. "Do you have their old locations?"

The fox studied his computer briefly, typing away, before answering, "Y-yeah."

"Where?"

Tails flipped his monitor around so Shadow could see. Similar to this morning, lights on a radar screen pulsated, signifying the previous location of the emeralds before they disappeared.

"But they aren't there now," Sonic argued. "How is that going to help?"

"The negative energy," Tails answered for Shadow, glimpsing at the striped hedgehog to confirm his line of reasoning.

He nodded once.

"If it's linked to what happened to Knuckles—and Rouge—then chances are that same energy is where the other emeralds were last located. I might be able to pick up its readings, once we're farther away from this," the fox added with a head bob towards the Master Emerald.

"Sounds like a plan to me," Sonic agreed. "Let's go!"

As he and Shadow headed towards the biplane, Tails noticeably hesitated as he looked back at the shrine.

"Bud?" he prompted.

"Is it smart to just leave it here?" he asked the hedgehogs.

"Well, it's not like anyone can take it, right?" Sonic offered after a few beats of awkward consideration. "Heh, not without a rude awakening, anyways..."

"Maybe we should leave a warning sign?" Tails suggested helpfully, peering at him. He earned a rather blank expression in response. "I mean, just in case?"

Sonic let out a breathy snort, shaking his head as he placed his hands on his sidekick's shoulders and navigated him towards the Tornado. Shadow took a little longer to follow this time, his own focus still on the odd green mist permeating the shrine.

As he eventually turned to follow the duo, Tails made a face and gazed up at the sky. "Did it rain?"

Sonic, now walking beside him, frowned. "No?"

"Then why are you damp?"