Nineteen.
Nineteen changeling spies in Canterlot, and only one month after the invasion.
And the worst part of it all? One of them was from the hive of Queen Chrysalis.
Celestia and Luna looked out over the group of eighteen creatures in front of them, a frown upon their faces. As far as either could tell, none of them knew why they were there; only that the princesses had called upon them.
Dionices had given them the results a few hours ago, the changeling also offering advice on how to address them so that they left without incident. Unfortunately, she also warned them that by calling them out, they could be inviting a hostile hive to attack Equestria in the open in much the same manner as Queen Chrysalis and her hive did.
Despite the warning, the princesses elected to address the infiltrators anyway, hoping that being exposed would dissuade the various changeling hives from committing reprisals, as well as discourage any future attempts to place spies among the ranks of the guard.
Celestia took a breath as she stepped up to address the changelings before her.
"Good afternoon. I have called all of you here today because of information we have obtained during the physical examinations that were conducted earlier today. To start with, you all did pass with high marks, and are a shining example of what we are looking for in our guards."
"Unfortunately, you all are too good of a shining example. In fact, one might say you are all carbon copies of the gold standard."
The solar princess paused to see if any of them had picked up on what she was talking about, and going by all of the looks directed towards her, they all did.
"Since there is no question about what all I am talking about, I will get right to the heart of the matter. I know that none of you are the ones responsible for the attack last month at my niece's wedding. For that reason, I will not hold any kind of grudge against you. However, falsifying your identity to become a member of the royal guard is a criminal act, and as a gesture of good will, I will pardon all of you for committing this crime just this once, provided you all leave without incident and do not return."
"And what?" one of the false guards questioned. "You want us to just leave so you can tail one of us back to our homes? Reveal the locations of our hives?"
"We have no interest in causing acts of violence, so long as a peace can be maintained. We are granting you this clemency so that we can maintain the peace that exists now. If you leave, we will not follow but to the city limits. If you refuse and attempt to fight, then you will be treated as a hostile entity."
"What my sister speaks is truth," Luna cut in. "We wish to maintain a state of peace. I will not lie and say that we don't want to bring those responsible for the attack at the royal wedding to justice, but we will not provoke an unnecessary war to do so. If you wish for further clemency, then we ask that you share with us any and all knowledge you have of the hive that attacked us and its whereabouts."
“And why should we share that with you?” another asked.
“From what we can gather, all of your kind predicate their existence on remaining in hiding, relegating yourselves to being nothing more than old pony tales and boogeymares that scare foals into behaving properly. It would seem to us that your hives would want to punish those changelings for that transgression.”
"Why you want that hive punished and why we want it punished are two different things!" a changeling spat back at the princesses.
"But we both still wish for them to answer for the wrongs they've committed against us, even if the perceived crimes are wholly different from one another."
A different changeling glared. "We've been watching you ponies for some time now, and you've never developed any method of detecting us before. In fact, you've haven't even come close. What changed?"
"That is classified knowledge that shall remain classified until such a time as we are sure it is appropriate to disclose it," Luna answered, returning the glare. It remained silent for some time before one of the changelings let out a sigh of defeat.
"Well, I don't know quite how you did it, but you caught us, so, good game, I guess."
The changeling moved forward towards the princesses. "If you wish for me to leave, then I leave."
Celestia nodded. "I do not know if you serve a queen or a king, but tell them that we only do what we do to safeguard our citizens. If they wish to send emissaries, we are open to diplomatic discussion."
The changeling scoffed. "I'll pass on the message, but I doubt they will wish to do so."
"Then you may leave now."
The changeling made no gesture towards the princess, but left without further comment. After a moment, several other changelings decided to leave. After a minute or so, the room had cleared out.
"Well, that went better than we had expected," Luna said a few moments after the last had left.
"Admittedly, yes," Celestia reluctantly agreed, "but I wish it could have yielded results for us regarding finding Queen Chrysalis and her hive."
"They may not have had any information, or maybe they did withhold it intentionally, but that matters little now. Besides, we still have one of the attackers here in the castle.
Celestia perked up a bit upon being reminded of that. "Yes, we do. Let us collect ourselves before confronting this lone member of her hive."
"Yes, but let us also consult with Dionices; she may very well have some tips or advice on how to best interrogate this straggler we have snared today."
Celestia nodded to her sister. "Yes, I believe that is a good idea."
Sitting in an interrogation room in the dungeons of Canterlot Castle was an undisguised changeling. Their eyes were arctic blue and carapace a navy blue, and they were glaring at the one-way glass it knew concealed several ponies behind it.
On the other side of the glass, Princess Celestia, Luna, Dionices, and several of the guard commanders were looking in on the prisoner in the other room.
"Nopony told this changeling why it was being brought down here," one commander pointed out. "Why did it disspell its disguise?"
"Because you brought him to the interrogation rooms instead of a private room or office," Dionices pointed out. "It knows something is up."
"We couldn't risk it escaping!" another commander defended. "If we had used an office or private room, it could've figured out what was going on then and made an attempt to escape! We did this to ensure that this prisoner wouldn't get awayif it tried!"
"And in the process, quite possibly ruined any chance of getting any kind of meaningful information from them!"
"Enough!" Celestia spoke, silencing everypony in the room. "What is done is done, and there's no undoing it. We have to work with what has been given to us now."
Turning to Dionices, she asked the changeling, "Despite the current circumstances, is there any way still we can get some kind of useful intelligence from this changeling?"
Dionices frowned, but the let out a breath as she answered the princess. "There is, but... you ponies probably won't like it too much."
"We are all ears," Luna said in a prodding manner.
"The only thing I can think of is what some of the detective novels call the Good Cop, Bad Cop routine. Basically, one pony goes in and tries to act like they're on the prisoner's side, and the other pony... doesn't."
"Doesn't how?" a commander asks. "Threatens to send them to the dungeons without a second thought? Withhold food and water until they give something up?"
"Firstly, we don't require traditional food," Dionices pointed out,"and the changelings in many of the other hives are more or less in a state of perpetual starvation, so that second threat is pointless. Secondly, sitting in a prison cell for long periods of time is not really a punishment for a changeling. Most often, we'll go into a light hibernation in order to conserve energy."
"Then I take it to mean that the bad cop in this scenario acts out in unpleasant ways, such as committing acts of physical violence against the prisoner?" Celestia intoned, getting a nod from Dionices.
"Out of the question!" Luna refused. "Even before the time of my banishment, our laws forbade any type of action such as that against a prisoner, even one that could be considered guilty of war crimes."
"My apologies, but I don't think you're going to get any information from this changeling unless you are willing to do things not as gently as you're used to doing."
"Barring our laws," Celestia interjects, "there is also the matter of the changeling refusing out of loyalty to their queen. It is not an official rule, but many of our guards are instructed to do everything they can to protect our kingdom, even giving their lives when necessary. I can't imagine Queen Chrysalis, or even your king, expecting any different of those whom she leads."
"While I can attest that that is usually true, you may find this changeling... a little more pliable in that regard."
Celestia and Luna looked at Dionices in confusion.
"What do you mean?" Luna asked.
"Think of it like this: you're a changeling serving under Queen Chrysalis, and she's promised you an end to the hunger you've suffered through your whole life, and just when it seems that dream is about to come true, you're blasted who knows how many miles in whichever direction, likely to fall to your doom but you somehow survive, and after finding a few of your other hivemates, learn that the reason you were shot out of Canterlot in the first place was because your queen chose that exact moment to be the worst infiltrator in history by not only not bothering to learn how to be the pony she was replacing, but also sending the one pony that could single her out to the place where you're keeping the pony you've replaced prisoner, thereby facilitating that pony's escape, and them when she had the opportunity to recapture both ponies, spent all of her time gloating over a victory she never actually had to begin with."
Dionices paused a moment to take a breath.
"Now, what would your opinion be of such a queen?"
Celestia and Luna think on it for only a moment.
"I wouldn't be too happy with her," Luna admitted first.
"Neither would I," Celestia then voiced her agreement.
"But there's no guarantee that we would meet with success that way," a commander pointed out. “They may choose to blame us for the failure of their queen, or simply be so indoctrinated to serving her that they would ignore the facts surrounding their defeat completely.”
Both princesses flinch upon hearing that.
"So it is a risky roll of the dice," Luna summarized.
"All I have to give you is that. I'm sorry I can't be of much more assistance."
"Couldn't you join us in the interrogation?"
"No. Once they see me, they'll realize what happened and redouble their escape efforts to get back to Queen Chrysalis and report that another hive is helping the ponies."
"They would?"
"Yes. They were distracted by the other ponies during the medical exam, but when if we all went in there together, they'd quickly deduce that I was a changeling and realize I ratted them out."
"Then why not try a different disguise?"
"That wouldn't work. The changeling in there would feel out your emotions, and once they got to me and didn't sense much from me, it would be glaringly obvious."
"So we must do this ourselves, and we must not hold back on being forceful? I do not like this."
"Nor do I, sister," Celestia agreed,"but what other option do we have?"
"It won't be so simple," Luna countered, stomping her hoof lightly. "We have no idea how long this changeling has been here, other than just one month. In that time, they've likely reviewed all applicable information relating to the guard, and in this instance, gone over everything relating to interrogation, including what we can and cannot do. If we went through with this, then that changeling, in spite of its status as a hostile entity to Equestria, and the rest of the world proper, could file suit against us for wrongful treatment of a war prisoner. Do you know what kinds of trouble that will cause us?"
"I am aware, sister; I helped to draft those very laws myself, and all applicable amendments to them as well. We would lose trade ties with many nations, longstanding peace treaties could be absolved, and we, along with many of our guards, could be tried for war crimes. The situation is not ideal in any capacity."
"So I must ask again: is there not another way?"
Celestia chewed on her lip as she thought over Luna's question. A part of her wished to think there really was some method that would get them out of this mess, but another that saw what Dionices was saying and how futile any tactic they used would be.
"Dionices, are you familiar with our laws regarding treatment of prisoners?" she asked the changeling.
"I am, but that is the choice you have before you: do nothing and be no closer to finding the changeling queen, or take the risk and possibly get a vital clue to her whereabouts."
Again, Celestia was left thinking. A guard, however, realized something.
"Your highnesses, only we, our cabinet of guards, and the changeling realize what is actually going on here, correct?"
Celestia looked at them, a bit of puzzlement on her face. "Yes. Nopony else is aware of what this guard actually is, and only thinks we wish to have a private discussion in a secure location."
"Then we do not have a changeling prisoner."
"What?"
"I suggest that we keep this changeling prisoner off of the books. Only everypony present here in this room will know of them."
Celestia blanched at the insinuation. "Are you to tell me that we cover up the capture of this changeling?"
"As I said, we do not have one in our custody."
"I fear that this guard may have the best idea, your highness," Dionices said in agreement. "Turning this into a... clandestine operation, might help you more than trying to do this by the book."
"I do not agree with this," Celestia stated adamantly, though not looking her sister of the changeling advisor in the eyes.
"Sister, our enemies do not play fair!” the guard pointed out. “Why should we be expected to do the same?"
"Because us having morals and upholding them is what sets us apart from them!"
"If I may?" Dionices interjected. "This drone was not here by its own choosing; the queen ordered it to be here, and if it was ordered to be in this specific place, then that means that she is gathering intelligence to commit another attack. Simply put, you have a spy here in your midst, and if you wish to get what information you want, then I must be the bearer of bad news and say that you stoop to their level and do it by any means necessary."
Celestia turns away, tears starting to form in the corners of her eyes. "I do not wish to do it this way."
Luna, having heard the arguments, sighed in defeat. “Maybe there is no other way.”
“Luna?”
"From where we stand sister, we do not see another choice. If it will help ease your feelings, then we can offer an amnesty to this prisoner once we have captured Queen Chrysalis."
"What good will an amnesty do if the prisoner is uncooperative? Or worse yet, what if the prisoner has no information? Then our actions will have been for nothing!"
Neither Luna, Dionices, or any other pony present had a counter for that argument. The solar princes paced back and forth for a few moments, chewing over the idea. Ultimately, she also let out a defeated sigh.
"I will speak to the prisoner alone," Celestia then decided. Luna was quick to voice her disagreement.
"Sister, I-"
"You may interview this changeling once I have finished," were Celestia's final words as she entered the interrogation room.