As she had grown into a habit of when she wasn't otherwise occupied, Umbra sat atop the castle, looking out over her domain. Well, it wasn't her domain. Cadance had dibs! Umbra was an assistant guardian, yes. She had no interest in its governance, really, so long as it was being done fairly. So far she could see, Cadance was a pretty nice ruler to have.
No, Umbra was quite fine with the pretty pink princess. It was up to her, the shadowy guardian, to keep an eye on what would threaten her and the other innocents of the city. Her eyes flashed darkly as she pressed her perceptions. "Darkness of the heart, become plain to me." Words were still not required, but she still found them cool, and that was reason enough, right? The spell she was using had a... troubled past.
It revealed lingering malice, the sort someone may be about to enact. A mugger creeping up on someone would be bright with it. Someone planning a crime, especially a violent one that may hurt someone, or something if it was vast enough. Or they could just be someone who enjoyed those kinds of things. The glow didn't prove any given person was guilty of a darn thing.
Which is where the problems came from. Darker ponies used it to look for fellows to plot dark things with. Sometimes it worked, which was bad. And sometimes it didn't, which could be just as bad, depending on how the interaction went. Bright ponies would take a shadowed heart as a reason to cast doubt and even harm on a suspected bad person. It was a big ethical mess that a lot of prior shadow users ignored in favor of their own point of view.
Umbra just wanted a fancy magic radar. It would point her at potential problems. She could stop in and say hi! No arrests for having a bad day. She'd had her own shadowed heart plenty of times, being upset because someone else did seemed silly and a bit petty. Fortunately, the ponies of the crystal empire, or maybe ponies in general, were not a shadowy sort. Most of them were invisible to her shadow-vision.
Well, that and also tucked in and sleeping. It was the night. The city was not known for its thumping night life. It was quiet, and she scanned, feeling perhaps a little more like an equine batman. She had donned her red cape, the one she came within. It flapped in the breeze just so. "I am the dark terror that guards the good people of the empire!"
There, a snatch of light. Well, light was the wrong word for it. Color? A sensation of movement. Her eyes trained on the area, leaning forward. There, another faint swirl, a rush of shadowed movement. "There you are..." She flashed a great fanged smile. "Time to say hello." There weren't a lot of good reasons she could figure for a pony to be darting from cover to cover like that, avoiding the main roads in the middle of the night, creeping around.
Maybe they did! She'd find out. First step, say hi.
She released her grasp on the physical, becoming little more than two shadowy eyes. Unlike Sombra, locked in a perpetual scowl, Umbra's eyes were more of a kind and curious expression as they drifted through the night sky, darting on the breeze she cut through. Being able to go shadow was the best! And it wasn't, technically, a spell. It was... just something she could do. There was no horn-magic involved. Like crystal work, it was just something that was a part of her. How did it work? Heck if she knew! But she liked it.
The darting figure surged out to cross a street, but found an Umbra in the way. "Good evening," she called as she returned to her fluffy default state. "Everything alright?"
The creature was not a pony. Its features were... It was hard to place, crooked and emphasizing all the sharp bits, eyes hallow pits with no pupils. It screeched at her, a howl as it darted back where it had come from.
"Wait!" She felt silly the instant she said it. How often did asking something or someone to wait when they were running work? Not often! What even was that thing? She broke into a gallop after it, but it was fast, flowing from dark to dark. It had given up all pretense of stealth, and proved it could be quite the rapid thing, lost to her sight uncomfortably fast. "What even..." Umbra sank to her haunches, frowning at where it had been. "Better report...." And she returned to the castle with new news to share.
The next morning, Shining scowled, hooves steepled. "That sounds like trouble. It wasn't a pony then?"
"Pretty sure not." Umbra shrugged softly. "I mean, sorta pony shaped? It had cute little ears and a snoot." She pointed at her own proud pony snoot. "But it was all off. Really creepy. Like if you asked a kid to draw a pony monster that bumped in the night, you'd probably get this."
Cadance gave a thoughtful hum. "I see... I'm glad you spotted it. Did it do anything?"
"It was skulking around. I thought I'd stop in, say hi, figure out what it was up to, but the moment it saw me, it hightailed it out of there." Umbra swished one hoof in an impression of speed. "Bam, like that. It was a shadow creature, that much I'm pretty sure of. Which just makes me feel bad. I mean... I'm a shadow creature too." She rubbed at her cheek. "But it seemed like the not-nice kind. Oh!" She pulled off her red cloak. "Don't need this when I'm not on patrol."
Cadance's expression lifted into a kind smile. "Why were you wearing that? I thought you didn't like it."
Umbra hugged the removed clothing. "The right clothes for the job. The cloak looked pretty good for a watcher of the night." She burst into little giggles. "Which I was! I'm glad to report the city was pretty peaceful, minus that shadow critter."
"Thank Celestia for that." Shining nodded softly. "But that leaves us with a problem. You may not be able to answer this, but did it feel strong?"
Perhaps surprisingly, Umbra shook her head without doubt. "Oh no. The shadow it was putting out was kinda small." She raised two hooves close together. "I don't think it was that strong at all."
Cadance crossed her arms. "I think we found your creatures, scratching at the wall, and they've broken through. The ones in your dream felt like a massive threat. This one must..."
"--be a scout," cut in Shining. "Trouble will soon be on our doorstep." His eyes fixed on Umbra. "Do you have any idea what it wanted?"
"I woulda said!" she cried, folding the cloak carefully. "It was searching for something. I want to say... from above... it woulda run into the crystal heart."
Both of the rulers' brows came down in a mutual frown. Cadance clopped lightly at the ground. "Then we must secure the heart as best we can. Shining?"
"Already drafting up new shifts." Mentally, clearly. No pad was in sight to take notes on. "That is valuable intel. Thank you, Umbra."
Umbra beamed at the thanks. "Just doing my part. They show up to detect shadow spells, which... makes sense."
Cadance raised a brow at that. "Detect shadow is a spell?"
Umbra quickly bobbed her head. "Oh yeah, here let me try." Her eyes began to trail shadow as her vision slid. Shining was free of shadow. Cadance, on the other hoof, was not just free of shadow. She was a brilliant anti-shadow that hurt to look at, but was dazzling all the same. It was like looking into the sun, leaving Umbra slack jawed at the multi-colored brilliance of it that washed over her in waves she could feel with the spell active. "Wow..."
Suddenly she could see nothing. Cadance had put a hoof over her face, allowing the stinging to die down, tears still flowing. Not emotional tears, but cleansing tears, her eyes desperately trying to mitigate the stinging of gazing into the sun. "Are you alright?"
"Cadance, you are so pretty."
Shining chuckled at that. "Umbra has you pegged there."
Cadance smiled a little. "Thank you, but you looked like you were... in pain. Is everything alright?"
"If shadow is one thing." She raised a hoof to her left. "You are about the opposite." She raised her other hoof as far to the right as she could go. "I could see shadow, and you were so not that I could see it too. Like rainbow waves..." She sagged a little. "I want to be a pretty magic pony, not a shadow monster."
Shining set a hoof on Umbra's shoulders. "You are not a monster. Shadow, sure, but you're a very nice shadow pony that plays a mean game of O&O."
Umbra burst into giggles at that. "Are you still holding that nat 20 against me?"
"Always." Still, he nipped her closer ear. "Oh! Your idea, top notch. A shield can do the trick."
Umbra threw up her hooves. "It was my idea and now I'm the last one to get it right?!" She rose up to her hooves, blinking her wet eyes open, the spell no longer being held. "I'm sorry. I'm working on it, promise. You'll stop feeling what I feel soon."
Cadance inclined her head. "Another reason I acted so quickly. That did sting." She rubbed her head just beside her eyes. "Now that Shining and I can 'close that door', we can... resume our private functions."
Umbra suddenly burst into giggles. "You show Cadance what a pretty mare she is!"
That only got a more furious blush out of Shining. "Um..."
"Our resident master of shadows has spoken." Cadance nodded with all due gravity. "We can't deny that, now can we?"
Shining adjusted the collar he wasn't wearing. "I suppose we can't. But that's beside the point. What you saw may well be what will attack us. Shortly? We can't tell, but we have a face." An idea sprang to being. "Can you make a statue of it?"
Umbra blinked at that. "A statue?"
"So we know what it looks like." Shining nodded firmly. "You know how to make crystal statues more than you know how to draw, right?"
Umbra considered that. "Yeah... That makes sense! I'll make a statue, as good as I can. They're kinda ugly, but that isn't very fair. Not like we decide what we're born as."
Cadance smiled gently at Umbra's defense. "If they come in peace, I will gladly give them a chance. You have proven to us that shadow doesn't have to be malign of intent. Still..."
"Yeah..." Umbra sagged a little. "They didn't strike me as super friendly... A bad example for my case."
Shining rubbed at his left cheek. "If they are like you, shadow, then activating the heart may be enough to turn them back if it came to it. We'd just want to keep you safe if we did it."
Cadance grabbed Umbra, dragging the squeaking mare over. "Our connection remains, even if we can close the door. I would gladly shield you again, Umbra. I don't think the heart would want to hurt its defender."
"No... But it will. It can't help it. Even if the fire really likes the matchstick, both are going to be upset if they come in for a hug." Umbra quirked a smile at her imagined situation. "And all the tears the fire can manage won't bring the match back again."
Shining set a hoof on Umbra's other side that wasn't already pressed to Cadance. "That's what we're here for. The heart will do as the heart does, but we aren't crystal hearts."
"We won't let you get hurt." Cadance squeezed Umbra gently. "Thank you, for helping. Let's keep this city safe."