"Pacing doesn't help."
"I know."
"You will get used to it eventually."
"I know."
"We're going to die."
"I know."
"There's nothing you can--"
"I know!" Elytra shouted, slamming a hoof against the bars of the cage. One of the five guards assigned to them glanced back warily.
Carapace's wings twitched. For just a moment, it had tasted something coming off of the other Changeling. Anger. Thin, wispy, and fleeting, but still unmistakeable.
"What's wrong with you?" it asked, voice level.
The other Changeling was quiet for a long time, leaning against the bars. They were iron this time, instead of the opaque crystal of the last cage. Carapace half-wondered what it had originally been intended for. Iron was rare in the pony nations; it blocked unicorn magic, took away the pegasus ability to control the weather, and (if it was remembering correctly) it was one of the few known substances that could kill a full-grown alicorn. That was why all of their guards were earth ponies.
And, apparently, iron disrupted the powers of Changelings. All attempts to morph had yielded nothing.
Finally, Elytra spoke, in a hushed voice. "There's nothing wrong with me."
"You felt something. Just now." Carapace considered the flavor it had tasted several minutes ago. "We can't detect each other's emotions, usually. They're too shallow."
"I know." It wasn't looking at Carapace. "But...it's...it's normal."
"No, it isn't. I'm not like that."
"It's hard to explain, Carapace." Elytra tipped its head back and sighed deeply, a disconcertingly equine gesture. "I've been trying to figure out what to tell you for months, and I still don't know how to put it."
"I don't understand." Carapace closed its eyes. "Are you talking about why you wanted the Queen to think you were dead? Why you left the hive?"
"Yes, actually."
"What happened?" It kept its voice quiet. "What did you find out?"
Elytra took a deep breath. "You know the caverns of the Hive Mothers?"
Carapace nodded, thinking of the deep, steamy caves that housed the three surviving Mothers. They were ancient, alien creatures, and the sources of every precious egg of the swarm. Most Changelings, sentient or not, tended to avoid their quarters.
"There are tunnels beneath them."
"That's impossible. The chambers of the Mothers are at the very bottom of the--"
"I know. That's what I thought, too." It paused, then lowered its voice. "I don't think the Queen knows."
"Just...tell me how you got down there. And what you found." Despite itself, Carapace was curious. It wanted to know.
"I crawled through a miasma vent," Elytra replied.
Carapace snorted. "A death wish. Lovely, Elytra."
"No, I was just curious. I was bored and everypony was gone, attacking Canterlot. I had gotten tired of you and Gossamer. So I went exploring, in the places that I didn't usually go. In the caves where the Hive Mothers are, I saw a vent that wasn't releasing as much fog as they usually do.
"Looking back on it, it really was a stupid decision, but I'm glad that I went into it now. The fumes were terrible, as you would expect, but nothing that I couldn't handle. It wasn't more than a couple minutes before I reached the bottom of the shaft--and after I fell out of it, there were no more fumes. Almost like they were just meant to discourage anypony from entering the vents."
"So what did you find?" Carapace pressed, not bothering to keep the impatience out of its voice.
"There were...paintings, on the walls." Elytra made an odd little gesture with its hooves, evidently meant to illustrate the statement. "Very old, and probably done by ponies or something like them. There would be a gathering of tiny, simple paintings, that seemed to tell a story, and sometimes I could figure it out. And then there would be a much larger, much more detailed painting of just one event."
"Paintings?" Of what?"
"Of us. Of Changelings." Elytra's wings fluttered against its shell. "But we were different. And...it told...I learned...what we are, and what we're for."
Carapace learned forward, an uncharacteristic thrill of excitement working its way up through its thorax. "What?"
"We--" At a sudden chiming of crystal, Elytra's head whipped around. Their guards had all snapped to attention, parting to allow a purple unicorn and a massive stallion in opaque armor access to the cage.
Carapace's internal organs clenched painfully at the sight of Twilight. The anger and hate rolling off of her were second only to what Cadenza's had been when she made the journey down here. It closed its eyes and tried to brace itself.
"You can go," she said to the guards. "I want to talk to the Changelings alone."
"If you're certain, Lady Sparkle," one of them replied uneasily. Carapace opened its eyes in time to see his gaze flicker uncertainly to the armored stallion. His face was covered, his stance impassive. "Uh...if you don't mind me asking, who is that?"
"Prince Shining sent him to protect me," Twilight replied in a clipped tone. Without another word, the guards filed out of the room. Elytra pressed a forehoof to its mouth, probably stifling the urge to retch.
Carapace moved to the front of the cage, gently shouldering the other Changeling aside, even as Twilight approached. It held back a grimace and managed not to press a hoof to the bands of its stomach, even as the pain and nausea rose.
"What do you want?" it asked calmly.
Twilight stared at it for a long time. Her emotions flowed and ebbed, as if she were confused about what she should be feeling. The stallion in the dark armor stood immobile behind her.
"I trusted you," she began quietly.
"That was your mistake, not mine," Carapace replied immediately. Her eyes narrowed.
"Yeah, I realize that now." Her tone was bitter. "I can't believe that I actually fell for you whole act. I started to believe that, maybe, you weren't a monster like we believed. That maybe there was something equine inside you. That maybe...you were my friend."
She fell silent, and just stared again. Then she slowly shook her head.
"I guess I was wrong." Twilight turned and began to walk slowly towards the stairs. "You are a heartless monster, and I'm a fool."
Carapace felt a twinge deep inside that had nothing to do with indigestion.
She stopped, squared her withers, and said, without turning around, "Your execution is scheduled for tomorrow morning at dawn. Celestia and Luna will be there, just in case. Whatever Chrysalis had planned...it's ruined now."
"But--" Elytra began, stepping forward. Carapace glanced at it and shook its head.
"She won't believe us," it murmured. "It doesn't matter."
Twilight's ears flicked, and she half-turned, one hoof on the bottom step. "What--"
It was then that a hoof clad in dark crystal seemingly flicked out of nowhere, aiming for her head. She didn't have time to react. It clipped her temple and apparently knocked her out instantly. Twilight crumpled, and an involuntary snarl ripped its way out of Carapace.
Business-like, the dark-armored stallion dragged the unconscious mare into an alcove probably meant for storage. She wouldn't be noticed for quite some time in the shadows there.
Elytra's wings buzzed, lifting it a couple inches off the floor of the cage. Its mouth dropped open to display all four inches of its fangs. Carapace took the opposite approach, crouching down with its haunches against the bars in order to make itself a smaller target.
The stallion approached them, his hoofsteps heavy on the stone floor of the dungeon. Carapace hissed, but he took no notice. As they watched, he stopped just inches from the front of the cage, reached up with one forehoof, and removed his helmet.
Changeling fangs and pony eyes. With a burst of shock, Carapace recognized the hybrid monster that she had defended Twilight from in the garden.
He bent his head forward, and an aura of green magic, a shade darker and a little more solid than Carapace's own, sprang up around the lock.
"My name is Anomaly," he murmured. "I'm here to help you."