A/N: This fic is going to take place after Omniverse continuity. Although, to be honest, I'll probably be using the UAF alien designs over the Omniverse ones. A lot of the redesigns just look so ugly to me.

I've written a handful of fics for this fandom before, but to those who are new to me, don't worry. There's absolutely no crossover between my fics. This is going to be a plot-based stand alone, sort of intended to read like an episode or two-parter.

Speaking of episodes, this whole fic is based on Alien Force S3 E16, "The Secret of Chromastone." I must've watched that episode about seven times, and it still makes absolutely no fucking sense. I don't even like that episode, but it's pretty much the basis for this entire fic, so if you haven't seen it yet, I suggest either reading the Ben 10 Wiki on the episode (which isn't very good, but it will give you the basics) or making a quick stop over at KissCartoon. You'll need to know what happens in that episode to understand this fic.

Also, last thing, I swear. I made up a name for what Petrosapiens and their planet are made out of. That blue-ish crystal? I didn't want to refer to it as "the crystalline substance" for the entire fic, so I'm calling it peranite. Unless any of you all know what it's called, because I sure don't, and the Ben 10 Wiki only says that it's "silicon-based." Which doesn't really help.

"And as the laser grid came rushing at us, Tetrax grabbed me and shot through it like it was nothing. I got completely covered, so we were both fine, but our hoverboards crashed and exploded. Man, Rook, you should've seen Asmuth when I first met him. He was just going to let the Omnitrix self-destruct tick down and rip the universe apart." Oddly enough, the memory of almost killing himself and everyone in existence made Ben smile. He chuckled at his own story. "Of course, Vilgax showed up before I could convince Asmuth to help me out. The guy just doesn't know when to quit. I couldn't use the Omnitrix, but me and Tetrax and Myaxx, we—"

"You saved the day?" Rook guessed good-naturedly. He had his hands on the ship's control and his gaze firmly fixed on space, but he was still listening attentively to Ben's story.

"Big time," the human confirmed with a cocky grin. "Asmuth fixed the Omnitrix and gave me Way Big. I threw Vilgax so far that he was in orbit around Zenon for days. I'd saved the world before that, but that was the first time that I save the whole universe. The first of many," Ben finished proudly.

Rook spared him a fugitive glance. "Apologies. I must have misheard the beginning of that story. Were you not the one to endanger the universe in the first place?"

Sulking now, Ben sank down in his seat and folded his arms over his chest. "Yeah, but I still saved it. And I convinced Asmuth to go back to Galvan Prime while I did it. That's got to count for something, right?"

As much fun as it would have been to banter back and forth on Ben's total net contribution to the well-being of the universe, Rook settled for a nod. "Yes, I suppose that it does. I admit the story is interesting. That was not in your Plumber files."

"That's because it's one of the few stories that I didn't tell Grandpa about, back in the day," Ben said matter-of-factly. "It was just me and Gwen that time, and we both agreed on the flight back not to talk about it again. But I guess that I just broke that agreement, didn't I?" He shrugged, a smile on his face once more. Emotional rebounds were Ben's specialty. "Ah, well. It's been long enough. I'm sure she wouldn't mind."

As Rook went to reply, Ben suddenly gasped, getting up out of his seat to stand next to where Rook was piloting. He pressed his face against the glass, squinting at the blue-ish tint in front of them that was rapidly growing. They had entered the Petropia system. Its namesake was the only planet orbiting close to a slowly burning out white dwarf. Around them, also caught in the star's gravity, large chunks of peranite were whizzing by at high speeds. Plumber-standard cruisers were monitoring the space up ahead, but other than flashing their lights in greeting, they let Ben and Rook pass without issue.

"Ben, you have to sit so that I can land," Rook told his partner with a teasing scowl on his face. "We will be there soon. Staring at the planet will not make it approach any faster than I am already flying. And we are near the speed of light as it is."

There was a muttered complaint from the teenager, but Ben sat back down and buckled himself in as told. "Still, it's going to be nice to see Tetrax without someone or something trying to kill me," he said cheerfully. "It seems like we only hang out when there's some huge problem we have to solve. What did Grandpa say we're supposed to do here, again?"

"It is an official yearly Plumber check," Rook informed him. "It is a system that exists in Plumber-controlled areas of the galaxy. Struggling planets are visited yearly by higher-ranking representatives of the Plumbers, usually hand-picked by the Magistrata herself. It is a very serious task, Ben. Our job is to ensure that the planet is developing at an appropriate pace. They have only been back in existence for a year now."

Ben rolled his eyes. "Yeah, and who's the one that brought them all back? Or did you not read that part of the file? Spoiler alert, you're looking at him." He thumped his fist against his chest proudly. "Relax, partner. These people love me. It'll be an easy job, in and out in a week, no questions asked."

Shaking his head, Rook sighed but chose to stay quiet. Sometimes, it was better to let Ben's ego burn itself out. He would be at a more reasonable level of arrogance in the morning.

He shifted the ship into a slower speed as they entered Petropia's gravitational pull. The planet reflected so much light that Rook had to let the auto landing feature do most of the work for him. Looking directly at Petropia's surface for extended periods of time could blind a person. If it wasn't for the distinctly crystalline blue hue of its color, it could be confused for a small star from a distance. But that was the drawback of orbiting so close to a white dwarf.

"Man, Rook, you're gonna love Tetrax," Ben blurted out, barely containing his enthusiasm. "He's sorta like Kevin, but actually cool instead of just faking it to play hard to get with Gwen. I wish I still had that hoverboard he gave me. It's so cool, Rook, way less clunky than dragging the Tenn-Speed everywhere, and probably faster too, since I didn't have to worry about avoiding obstacles on the ground when I was flying. Ten-year-old me had the coolest stuff. How is that fair?"

Getting Ben to stop talking was impossible. He was far too excited about seeing his Petrosapien friend again. Rook let the sound of his partner's rambling become white noise while he double-checked that the ship was landing correctly.

As the ship dropped closer and closer to the surface of the planet, Ben eventually quieted himself. He was no less eager but hid it behind a grin instead of continuing to bounce off of the walls. The closer that they got to the Petropia, the less intense the light became. It never actually dimmed, but it was easier to bear with less surface area in their lines of sight.

The Petrosian Plumber base was made out of the same crystals that made the rest of their planet. Metals and wiring were only used where absolutely necessary. They were weaker than the peranite that made up the planet but seeing as how the crystal couldn't conduct electricity, they were forced to use it to make anything in the base work.

At the sight of the glimmering base, Ben let out a low whistle. "Wow," he muttered, "they didn't have that the last time I was here. The whole planet just looked like crystal mountains. They've done a lot in a year, huh?"

Rook nodded absently. "Yes, the Plumbers have been working hard to return Petropia to the way that it was before it was unfortunately destroyed. Whatever method you used to restore the planet, the buildings and artifacts did not come with it." He grimaced at the thought. "Thousands of years of history and culture… lost."

Hearing that, Ben sobered for a moment, but he quickly reverted to cheerfulness again. "We'll help them rebuild it. They can build a better city now. A blank slate to start over. And this time, they're not going to get wiped out, so they'll have plenty of history again in no time."

There were so many things wrong with that statement that Rook almost protested. But seeing the genuine look in Ben's eyes, he only chuckled. "I am sure that they would be relieved to hear that, Ben. I imagine that being wiped from existence is an experience that the planet would like to forget."

"Totally," Ben agreed. "I've been there before. A few times, actually. It never stops being tingly." Despite Rook's advisements, he had unbuckled himself and was rapidly tapping his foot against the ground, barely managing to stay seated.

They were close enough now to see the Plumbers managing the base. As Rook first assumed, most of them were Petrosapiens. This planet wasn't like Earth, which had only recently been deemed capable of handling Level 3 technology. Petropia had been far beyond that before getting obliterated, and they weren't as reliant on more experienced beings the way that humans were.

Of all the Petrosapiens milling around the outside of the base, Rook assumed that the only one not wearing a Plumber's uniform was Tetrax. He had never even heard of this being until Ben's enthusiastic stories during the flight. And for a file as detailed as Ben's, Rook found it hard to believe that Tetrax would have just accidentally been left out or overlooked. Something about the whole thing irked him, but he couldn't place his finger on what.

The ship jarred them both as it touched down. Ben almost fell out of his seat trying to stand before the landing was complete. If this embarrassed him, he didn't let it show.

"Rook, c'mon, you're taking too long," he groaned impatiently as his partner stopped to make sure that the equipment was all reading correctly and everything important was safely accounted for. "These guys can do all that boring technical junk. They're Plumbers, they can handle the Plumber-standard cruisers."

And while it was true that Rook had forgone his Proto-TRUK for a Plumber ship that had an FTL drive, so he didn't have a personal attachment to its state, he didn't see how any of that meant he shouldn't take the ship's well-being seriously. Rook was about to tell Ben as much, but his partner was as impatient as ever and had already opened the bay doors. Knowing how culturally ignorant Ben could be, Rook heaved a sigh of defeat before going after him.

"Must you always be so restless?" Rook asked dryly from Ben's side. He crossed his arms over his chest, waiting for the ramp to finish lowering.

Predictably, Ben didn't seem to notice this little detail. He shot Rook a grin. "You're being overdramatic. When have I ever been impatient?" And without waiting for the ramp to finish descending, Ben jogged out onto the platform. He reached the end of it just as it made contact with the ground and, not missing a beat, threw his arms around the only Petrosapien there who wasn't wearing a Plumber's uniform.

"Ben! Good to see you!" Tetrax greeted. He had a much deeper voice than Rook would have initially guessed. While Petrosapiens were naturally buff, especially the males, Tetrax looked like he worked at it. Compared to him, Ben looked like a faint breeze would blow him over. Not that it stopped Tetrax from hugging the human back. It was a brief embrace, over as soon as it had started. Neither of them seemed comfortable with openly displaying affection.

"Yeah," agreed Ben as he straightened back up. "It's nice to see you when nothing's in peril for once. Oh, right! Tetrax, this is Rook." As soon as his partner descended the platform to stand next to him, Ben grabbed Rook by the arm and yanked him closer. "He's my partner now that Gwen — you remember my cousin — and Kevin are doing their own thing. Rook, meet Tetrax."

Now that he was being addressed, Rook stood up straighter. He gave Tetrax a respectful nod. "It is nice to meet you, Mr. Shard. I am Rook Blonko, of the planet Revonnah. Magister Tennyson assigned me to partner with Ben. I have heard a lot about you from him."

Rook was expecting to leave it at that, but Tetrax instead reached out and grasped his hand. For a moment, he was frozen but then realized that Tetrax was giving him the human handshake greeting. He still didn't understand the concept too well but shook back. Based on the amused grin Ben was giving him though, Rook doubted that he was doing it correctly.

"Of course. Anyone who can keep a handle on Ben has my respect," Tetrax said. That got him a scowl from the human, but there wasn't any malice in it.

The absence of this Petrosapien from Ben's files still left Rook a little suspicious, but he relaxed. Tetrax didn't seem like a bad person and, based on the stories that Ben had told during the flight, he could be trusted at least marginally. Besides, as Tetrax had said, it took a special sort of person to keep Ben from getting himself killed. If nothing else, the two of them would have that in common.

One of the other Petrosapiens from their greeting party stepped forward. He was obviously the one in charge and held himself as though he had already earned their respect. Whereas Tetrax and Ben's Petrosapien form, Diamondhead, were the same shade of mint-cyan, the newcomer was a deep navy. His eyes were an electric lime, somehow managing to be more green than the Omnitrix.

"Welcome to Petropia, Ben Tennyson and Rook Blonko." He spoke with a rough voice that matched his no-nonsense demeanor. "I am Corporal Mantle, the Plumber officer assigned by Magister Argyle to be your escort. Behind me," he waved towards the three Petrosapiens standing at attention, "I have cadets Igneous, Popigai, and Kimberlite. For the seven rotations that you'll be staying on our world, we'll act as your guides, your informants, and your protectors, should the need arise."

As expected, Ben looked confused. Rook knew all of this already, having read the mission briefing they'd been given, but he didn't think that Ben remembered the assignment even being mentioned until they were already leaving.

"But we have Tetrax." Ben pointed to his friend. "Why do we need four bodyguards? I think that I can handle it if a street fight breaks out or something."

Corporal Mantle shook his head. "Tetrax is not a Plumber. Were your visit for leisure purposes, his presence wouldn't be a problem." Somehow, though, the thinly-veiled tone of disgust in Mantle's voice gave off the opposite impression. "This is a Plumber assignment. Magister Tennyson asked that Tetrax be allowed to accompany you, but that's the only exception that we can make. We understand who you are and what you've accomplished, but this is the proper procedure. Magister Argyle was very specific in his orders."

Ben snapped his mouth shut. He didn't look all that pleased, but he knew when a battle was lost. There was no chance in convincing Mantle to forget protocol anymore than there was a possibility of coaxing Rook into using contractions. At least Ben hadn't asked who Magister Argyle was. Showing ignorance of the man in charge of the only Plumber base on Petropia wouldn't have made a good first impression.

"While you're staying on this planet," Mantle continued, "we have only three rules for you, Tennyson, sir, and your partner to follow. The base itself is, of course, fully accessible to either one of you. Within certain parameters. Igneous!" He snapped his head around so suddenly that a bit of peranite splintered off of his neck. "What's rule number one?"

The young Petrosapien soldier stiffened, giving a salute. He was the same shade of blue as Tetrax, though his eyes were the color of candlelight. His lithe body type suggested that he relied more on speed than strength. "While outside of the base, wandering from the group is not permitted, sir! Everyone goes together or they don't go at all! Sir!"

Mantle gave a single nod of his head, turning his attention to the other young male. "Popigai! Rule number two, soldier!"

This cadet was pale lavender, quite a rare shade in Petrosapiens. He was much tenser than Igneous was and had even less muscle on his body. "Curfew is sundown to sunrise, sir! During these times, anyone spotted outside of the base will be immediately apprehended, no exceptions, sir!"

"Kimberlite!" Mantle turned to her next. "Rule number three, cadet!"

She seemed anxious but hid it well behind a cool scowl. "Don't go anywhere alone, sir! Even in secure locations, no one is permitted anywhere without an escort! No exceptions, sir!" Unlike her fellow cadets, Kimberlite looked battle ready. There was a certain gleam in her eyes and she was built like she could crush a mountain. Her body was a deep shade of jade, and with it came the impression that she was larger than life.

Throughout this exchange, Ben watched with a faint smile on his face, like he was remembering something that he thought fondly of. His expression quickly grew neutral again as Mantle turned back to them.

"You should know that Petropia has very strict laws. There will be no exceptions or leniency, not even for the Ben 10." His eyes narrowed. Oddly enough, Rook thought that there was a bit of admiration in those eyes as the Corporal stared hard at Ben. But he couldn't imagine why Mantle would be so cold if he respected the human. "Is that clear?"

The corner of Ben's mouth quirked up in a half-smirk. "Crystal," he replied with a nod.

Mantle stared for a moment longer, not understanding the human phrase, before finally deciding that it was an affirmative and giving a nod of his own. Briefly, Rook noticed Tetrax shoot Ben an amused look. "Excellent. Please, follow me. I'll show you where the two of you will be sleeping for the remainder of your stay."

They started off after him. Rook noticed the three cadets moving to flank them but put it out of his mind. Ben didn't seem the least bit bothered by the shadowing. In fact, he had already moved on and was talking animatedly.

"So much has changed since I last saw you, Tetrax. It's only been a year, but I don't know where to start." Ben was eager to try though, sneaking glances to gauge Tetrax's reaction as he began listing things off on his fingers. "I stopped an Incursean invasion of Earth, finished a Time War, went back to the beginning of time and got to see the universe being created, mastered full-control of Alien X—"

"Yes, I saw the trial for that," Tetrax added. He didn't look impressed so much as he did entertained, watching Ben prattle on with something akin to fondness. The other Petrosapiens, Rook noticed, looked increasingly awed and doubtful as Ben continued.

All of this went without the human's notice. "—and I met up with a bunch of alternate mes to fight evil versions of myself and Vilgax in another dimension, got a Ph.D. from college, freed a bunch of slaves that an alternate Ben had working for him, and held the Big Bang in my actual, literal hands, and I—"

Ben stopped talking when Tetrax chuckled. He stopped walking, and as he did, the entire group was forced to as well.

"All of that, huh? It's hard to believe that you're the same child who couldn't plan through a fight beyond throwing the hardest punches." Tetrax placed a hand on Ben's head, ruffling his hair much to the chagrin of the teenager.

Huffing, Ben flattened his hair back down and stood up straight again. "I've come a long way since—" He caught Rook's gaze, smiling faintly. "And, well, y'know… I've had some pretty great partners. I couldn't've stopped the Highbreed invasion way back when without Gwen and Kevin, and I wouldn't've been able to make sure the universe got created without Rook's help."

There was a knowing look on Tetrax's face as he and Rook shared a glance. Whatever the Petrosapien saw, it must have been satisfactory, because he nodded. "I can see that. Your partner must be remarkable if all of your stories are true. But slow down, Ben. We have plenty of time to catch up. Now, what's this about a Time War?"

So Ben began to describe it to him.

There were moments that Rook would have to fill in, either because Ben wasn't sure how to broach a topic so complex or because the logistics of it were so confusing that they still barely understood what happened. Mostly though, Ben carried the story by himself while Rook memorized what he could of the Plumber base. In was enormous, easily three times bigger than Earth's base. The outside was deceitfully small — most of the structure was contained beneath the planet's diamond-hard surface.

"—couldn't stop Maltruant from putting his body back together. He disappeared with himself intact, but then I got contacted by this time traveling friend of mine, Spanner, and he sent me twenty years in the future to fight Maltruant with my future self. He was getting away, so me and Rook got in our Time Cycles and Professor Paradox—" Ben was cut off when, in front of them, Mantle stopped walking.

The Corporal pulled a Plumber's badge from his utility belt, holding it up to a scanner. The door next to it slid open with a smooth whir, revealing sparsely decorated sleeping quarters. "The scanners in the base will recognize the Omnitrix," he added, turning to Rook and Ben. "This is where the two of you will retire to every night. Curfew is sundown. You can still wander the base if one of us is with you, but otherwise, it's expected that you'll stay in your quarters. Under no circumstances are you to go outside. Understand?"

The room itself wasn't that big. It had space for them to set their bags (which had been left on the ship in Ben's rush), a mirror along the far wall, a steel chair, and two beds. The walls and floor and ceiling were, of course, peranite. The beds were too, though blankets and pillows had been added as an accommodation for the non-silicon based life forms.

With a frown on his face, Ben pretended to study it for a moment before shooting Mantle a thumbs up. "Got it. So, when do we move on to the exciting things?"

"Ben," Rook sighed, cutting off a frustrated-looking Mantle, "this is a serious assignment. It will not be as exciting as what we are used to dealing with while on patrol."

Unphased, Ben grinned. The flicker of doubt that crossed his face just a second before that was gone as easily as flipping a switch. To someone who hadn't been paying attention, the slip would have been entirely unnoticeable.

"Psh, don't be such a downer, Rook! We're protecting people. That's always exciting, right?" Still, there was a touch more seriousness to Ben's face when he turned back to Mantle. "So now that the tour's out of the way, we get to see the city, right? I didn't get to sightsee much the last time I was here."

Evidently, Mantle had decided that being incensed wasn't worth the effort. He sighed, giving a stiff nod. "Of course. Over the seven days that you'll be staying here, you'll be seeing seven cities. Today, we'll be showing you our capital city, Petra." His voice was aglow with pride at the mention of it.

A smirk came to Ben's face. "Not much for names, huh?" He leaned over, muttering directly to Tetrax.

The Petrosapien snorted, corners of his mouth turning up into a faint smile. He nodded his agreement, replying so quietly that even Rook couldn't hear it. But it made Ben chuckle, and the two shuffled forward after the retreating Plumbers.

Rook paused, watching their backs for a long moment. Something about Tetrax was making his stomach churn. He didn't trust the warrior, as much as he wanted to. Of all the things that Rook had learned since becoming a Plumber, being comfortable with trusting his gut instinct had been one of the most valuable. He may not have been able to put his finger on the reason why or even have any evidence to justify his feelings, but something about Tetrax was off. Rook wouldn't say anything for now, out of respect for Ben's friend and what he had done to save the universe, but he kept a wary eye on Tetrax as they continued.

The hallway folded through many twists and turns. As confusing as it was, Rook did his best to memorize the path they were taking. Sleep would be necessary eventually and he didn't want to ask Mantle to show them to the room a second time. He was so focused on this self-designated task that Rook didn't notice anything changing until Ben let out a gasp.

Automatically, Rook was on edge. He found himself relaxing almost immediately though, and was thankful for being towards the back of the group. No one had seen his hands twitch for the Proto-Tool slung over his shoulder. Rook bit back a curse of annoyance. This was a serious job, yes, but not a dangerous one. A year of being Ben's partner had gotten to him more than he initially thought.

Rather than an enemy trying to kill them for one reason or another, what had made Ben gasp was merely the glittering sky bridge they found themselves in.

Like everything else, it was made of peranite. But instead of the harsh angles and factory smooth walls that designated the main base, the bridge was more of a tunnel. The top arched high over their heads, closing up a wide platform that extended from the side of the Plumbers' base for almost a mile, slowly sinking into the surface of the planet. Rook could see why Ben had been impressed. It was a marvel of innovation. Even without the impressive ingenuity, the way that the white sunlight caught on the thin crystal and made the air itself glow had Rook staring for longer than he wanted to admit.

The sky bridge was decently full of other Petrosapiens, as well. All of them were in Plumber uniforms and all of them stared at their little group. Not all of the stares felt friendly, but Rook had been living among humans for so long and had gotten so accustomed to their open expressions that he had trouble figuring out what these strangers were thinking. He tried to put it out of mind. Their opinions, though insightful, were ultimately irrelevant. More pertinent, Rook was curious as to what the Petrosapiens had to be mad about. Mantle hadn't seen very pleased with Ben either, but if the story that Rook had heard was true, then hadn't the human restored their planet and all of them to life? Maybe Ben's ego was rubbing off on him, but Rook was wondering why these people weren't worshipping the ground where Ben walked. That would at least make more sense than some of the glares sent their way.

"This bridge leads us out directly to Petra," Mantle informed the group as they walked. "It was one of the first things to be constructed after our planet was revived. Peranite is a notoriously difficult material to work with, but over the eons, the people of Petropia have become masters in the craft. It's the perfect building material — lightweight and sturdy, but flexible enough that we've never wanted for the steel machinations of other civilizations," he said, puffing his chest up proudly. The sight reminded Rook a bit of a strutting bird.

"It's been quite the time saver," one of the cadets, Popigai, added in. "Petra is by far our largest and most profitable city. Since the successful installation of the bridge, time spent walking between the city and the base has been reduced by forty-six percent." He paused, then continued, "I was on the design team for one of the models, as it so happens."

"Woah, really?" Ben looked genuinely interested, catching Popigai off-guard. Nervous, the cadet nodded and tried to return to their professional silence, but Ben didn't seem to notice. "How come they didn't end up going with your design, then? I didn't think that bridges of diamond would need to be picky."

Any hope of maintaining the quiet was instantly lost. "Oh, not at all, sir," Popigai said eagerly. "Peranite is a wonderful material, but melding it together well enough to hold up a mile of bridge is more complex than actual rocket science. My team's design failed because we mistakenly tried to build a bridge like any other room. As it turns out, the rounded tunnel made for a more aerodynamic and balanced final product."

"It is indeed marvelous," Rook commented, looking over his head. "How did the design team manage to make the walls and ceiling so thin while retaining the necessary stability from the elements?"

And that was how the next fifteen minutes passed by talking about bridge construction. Of all the times for Ben to pay attention to something besides the Omnitrix, it had to be about diamond-hard bridges. Rook silently prayed to Brallada that his partner might actually retain some of this information. Understanding the basics of engineering and mechanics certainly couldn't do any harm.

Unfortunately, everyone else in the group seemed about ready to bash their heads in by the time their party of seven left the bridge. The conversation had shifted to an argument on the laws of physics (Ben didn't quite grasp why the planet's size would affect how bridges had to be built) when it suddenly went quiet.

Rook felt the same. The sky bridge had been impressive to be sure, but he was officially speechless as he looked at what lay ahead of him.

Following the gentle, downward slope that had brought them in the base of the mountain and deeper still, there was a Plumber check-point. Badges were scanned and people were waved on ahead as their credentials checked out. It was all pretty typical, but that wasn't what had caught the attention of the two off-worlders.

The mountain had been hollowed. How, Rook couldn't fathom, but he didn't need to understand to stare with big eyes and a loose jaw. Light entered the cavern from the weak places in the peranite dome above them, making the entire, sprawling city light up like the night sky. The buildings reflected that light in turn, until not an inch of the metropolis was still in the dark. It must have taken months of non-stop labor to get results like this. Homes and shops jutted out from the ground like they had grown there, twisting in elaborate swirls and spirals to defy gravity. The taller buildings nearly brushed the edge of the dome. It looked like a paradise. Wide streets were bustling with crystalline people. There wasn't a hint of trash in sight. Fluorescent moss had been grown in purposeful patches to light up the streets when night fell. Even from their vantage point overlooking the enormous underground city, Rook could hear laughter and voices floating up to greet his ears.

He didn't realize that he was smiling until he looked over at Ben and noticed the identical grin on his partner's face. They locked eyes for a moment, but there wasn't a way to describe what they were feeling. There was nothing that either of them had experienced that could compare to this.

"All of this… was constructed in the past year?" Rook asked weakly. He didn't need to turn to see Mantle's smug look. The sound of cracking told him that Popigai had nodded. With a joking smile, Rook directed his next words at Ben. "I doubt that we will be needing to return to check on Petropia once this week is completed. This is…"

"Amazing," Ben finished for him. The human was back to bouncing on the balls of his feet, visibly having to restrain himself from grabbing Rook and tearing off into the city. "C'mon. I brought this planet back, and I wanna see some of what they've accomplished."

Tetrax chuckled, clapping a hand on Ben's shoulder. The force of the gesture almost sent the boy sprawling, though Tetrax didn't seem to notice. He was swelling with pride as he looked out over Petra. "Not all of our cities are this impressive, but your Revonnahgander partner has a point, Ben. After this, your next visits should only need to be for leisure. We've come a long way in a year. A very long way."

There was that gut feeling again — the sensation that Rook was missing something. He had noticed the hint in Tetrax's statement and the way that Mantle's face tightened just a fraction. Rook almost asked about it, but before he could, Ben grabbed him by the wrist and pulled hard. Surprised, Rook stumbled forward, being dragged along by his friend. Evidently, patience still wasn't Ben's strong suit.

"Do you think we could ever get Undertown to be this sparkly?" Ben yammered on excitedly. "I wish I had seen this stuff the last time I was here. Look at all of this, Rook! Can you believe that this place used to be covered in cities like this? Do you think that they have smoothies somewhere down there?"

And Rook could have very easily pulled himself free of Ben's grip. He should have reminded his partner of how serious this was supposed to be. But the excitement was contagious and Rook didn't have the heart to spoil Ben's good mood on their first day here. He put thoughts of unease and guarded looks out of his head, and instead indulged Ben's fantasy of crystal-looking smoothies.

A/N: Obligatory world-building chapter. I've got to set the scene, you know? The next chapter will pick up.

Those who have read my rare multi-chapter works before know that I like to name chapters with a theme. Usually, it's song titles or lyrics, but for this fic, I'm going to be using common idioms in the English language.

(Including the title of this fic. For those that want to look it up, the source of that idiom has some, uh, interesting implications in terms of foreshadowing.)

If you aren't sure what one of the chapter titles mean, you should look it up. And if you aren't sure how it ties into the chapter, just drop a comment. I'm the kind of AP English nerd who gets excited about language devices, so I'd love to talk about it.

Either way, it might be fun to learn something about idioms. The next chapter title will always be listed here, in the bottom author notes, and they can serve as a subtle way to tell you guys what's coming next. So that's something to get hyped for. Updates will happen weekly, every Sunday. Unless I forget. Which I inevitably will, at some point.

Chapter Two: The Devil's in the Details