Princesses Celestia and Luna were waiting in the throne room, both now dressed in their ceremonial garments, their manes and tails styled perfectly. Joining them were the Element Bearers, with the exception of Fluttershy and Twilight, all in their own dresses, as well as Shining Armor and Cadance. The bride and groom both looked a bit annoyed.
"I hope that Twilight will be here soon," Cadance remarked as she examined a nearby clock on a wall.
"She will be," Celestia told her niece. "Twilight told me that she may have found an answer to the question of why that lone changeling managed to get past your shield spell yesterday, but needed to conduct an experiment to be sure."
"And we did conduct that test," Shining pointed out, "so there really shouldn't be a reason why she isn't here now."
Celestia had considered telling him that Twilight had indeed found the answer to the question, but her student wanted to tell everypony at the same time and asked for her not to tell anypony yet, and to call everypony to the throne room as soon as she could.
"Please try to be patient," Cadance asked her soon-to-be husband. "I have a feeling that Twilight did find the answer and we're all going to have a tiny bit of closure regarding this whole invasion fiasco."
Shining Armor let out a heavy breath. "I am a bit annoyed that our wedding has been delayed yet again, but if we can get some ironclad and concrete answers regarding that matter, then I'm willing to wait just a tiny bit longer."
Another minute passed before a guard entered the throne room and announced Twilight's arrival.
"Twilight," Celestia greeted her student, "what news do you have for us?"
Twilight approached the dais and bowed to Celestia and Luna. "I believe that I have found the definitive answer as to how the changeling managed to get through the shield Cadance and Shining cast yesterday."
"I am glad to hear that, Twilight. Now, please tell us what you've found out."
Twilight cleared her throat as she prepared to explain the experiment and the result's implications.
"Well, I interviewed Cadance and Shining Armor about the spell they used. Specifically, I asked what kind of spell it was and what their intent was behind it. Both told me that the spell was the same spell taught to unicorn recruits in the royal guard, and that their intent was to expel the evil changelings from Canterlot."
"After some thinking, a possible solution came to me, but in order for me to be sure that the idea was sound, I needed to test it. I set up special equipment in the interrogation room of the dungeon and then asked Cadance and Shining Armor to join me down in the observation room adjacent to the interrogation room."
"For the experiment, I asked them to recast the shield spell they used yesterday against the changelings. I wanted everything about the spell to be the same as before, including the emotions they felt and their intent behind casting it."
"As they prepared to cast the spell, I went into the interrogation room and triple-checked all the instruments to make sure that they were calibrated properly, and I also brought in the most vital tool in testing my theory."
"The most vital tool?" Shining questioned.
Twilight nodded. "Let me show it to you."
She turned to the doors she had come in through and called out to a pony outside them.
"Bring it in!"
The throne room doors opened, and a squad of guards came into the throne room. In the center of the squad of guards was the changeling, wearing hoof bindings and a suppression ring on his horn.
Almost immediately, Shining Armor and Cadance glared at him, crouching into fighting stances.
Celestia and Luna both looked at each other and then to Twilight.
"Was this the reason you...?" Celestia asked, making a gesture with her hoof.
"It was. You see, Shining and Cadance, I had to lie to the both of you a bit. Most of the equipment you saw through the glass was just old experimental equipment that I used to use while studying here in the castle. It only served one purpose during the experiment: it prevented you from seeing Thorax."
"And why didn't you want us seeing him?" Shining asked, an edge to his voice.
"Because if you had seen Thorax, it would've affected your spell. The emotions would've been more potent and your intent would've likely changed to wanting to expel Thorax instead of evil changelings. I needed you to be unaware of Thorax so that I could test my theory."
"And what was this theory?" Cadance then asked.
Twilight stepped beside Thorax before answering Cadance's question. "You both said that you cast the spell with intent to expel all of the evil changelings from Canterlot, and according to the readouts from the few machines I was actually using, you did exactly that."
"Yes, we did," Shining affirmed, "and our efforts clearly failed if this Thorax is still here!"
"No, Shining" Twilight countered, "That spell worked exactly as intended."
Shining Armor looked at her with confusion. "What do you mean, worked as intended?"
"Exactly that. The shield spell expelled every evil changeling from the city..."
Twilight then turned to Thorax and gave him a smile.
"...and left the only one that isn't behind."
All the ponies gasped at the insinuation Twilight had made.
"Twilight, are you telling us that this changeling was spared because he isn't evil?" Celestia asked.
Twilight nodded. "Yes, I am. He hasn't tried to attack anypony, has made no efforts to escape, has answered all of our questions with no hesitation, and as I explained moments ago, was spared by Cadance and Shining's spell."
There was silence for a few moments. Most ponies were processing this new and very surprising information. Shining was gritting his teeth, trying to form a rebuttal of some sort but coming up short. Eventually, Princess Celestia broke the silence.
"Twilight, I do agree that your theory and supporting experiment seems sound, but you are a mare of science. In order for your findings to be considered completely sound, another pony must perform the same experiment you did and achieve the same results."
"Which is why I would like to ask you to recast Cadance and Shining's shield spell now," Twilight asked Celestia.
Again, the ponies gasped. Celestia considered it for a moment.
"You are certain that the result will be the same?"
"Yes, I am. Just use the same shield spell Cadance and Shining used, with the same intent to be to remove evil changelings from the area of effect, and if my theory holds water as I believe it to and have seen proven once before, Thorax should pass directly through your shield."
Twilight produced some papers and presented them to Celestia. The alicorn took them and read them over. Once finished, she looked back at her expectant student.
"Very well," Celestia closed her eyes and focused her magic, a small ball of yellowish white light forming at the end of her horn.
Thorax saw this and began whimpering. He was unsure if Celestia would actually cast the same shield spell, or one meant to eliminate him then and there. Unfortunately, with the suppression ring and the hoof bindings, he had no way to escape the wrath of the sun princess, if she chose to exterminate him now. All he could hope for was that he wouldn't make another mess like he had before.
Once her preparations were complete, Celestia opened her eyes and released the spell, a sphere of yellow energy expanding out from the tip of her horn. Thorax flinched and tucked his hooves in in a futile attempt to protect himself from the wall of energy.
Everypony watched as the princess's shield approached the changeling with bated breath, and then dropped their jaws as he phased through it completely.
Twilight, however, was grinning, happy to be proven correct to pretty much all the naysayers in the room.
Celestia dispelled the shield and the yellow energy was gone in a flash. Everypony in the room then looked from her, to the cowering changeling, and then back to the princess. None of them said anything for a few moments, then Princess Luna spoke.
"Well, sister?"
Celestia looked at Thorax in thought, then to her pupil, and then let out a sigh.
"What Twilight has told us is the truth. I have cast the spell as she has described it to me, and the results speak for themselves. If Thorax were indeed evil, the shield would have pushed him away as it did with the others of his kind."
"Surely you don't believe this?" Shining Armor protested. "There has to be some kind of problem with the spell."
"Captain Armor," Celestia addressed the stallion tersely, "there is nothing wrong with the shield spell. It is the very same you and every other guard before and after your time in training has learned since my sister and I personally crafted it more than two thousand years ago. The only thing that changes with that spell is the intent of the caster and the emotions they feel at the time. If your intent was to banish evil from the city and spare all who are good, then the fact that this changeling was spared should be more than enough proof that your sister is correct."
Shining sputtered as he tried to come up with a counterargument, but was stopped as a hoof rested on his withers.
"Shiny," Cadance said to her fiance, "I know that what happened to you because of the changeling queen was horrible. Even what she did to me was reprehensible beyond words, but can you really judge the whole based on the acts of a few?"
"What are you talking about, Cady?" Shining asked in disbelief.
"I don't think every changeling is evil, or at least not inherently evil; perhaps they're just misguided and don't know any better. In fact, the changelings that came to the city may only be a small part of the whole. Perhaps what we saw were the ones who agreed with the queen's plan."
Shining wanted to protest Cadance's argument, but it was sound. He couldn't say for certain that he'd seen every changeling in existence, and because of that, he couldn't say definitively that all of them were evil. With no way to counter her suggestion, the stallion conceded on one point.
"Okay, perhaps Thorax here isn't evil, but that doesn't excuse the fact that he's probably drained a pony of love at some point in the past."
Nopony could really argue against the point Shining had just made. Despite the claims about Thorax not being evil, there was no denying the plausibility that he had done what was suggested.
"That might be," Twilight conceded to her brother, "but is it that much different than a manticore going after a pony to eat it, or a dragon for that matter?"
Shining looked at his sister with shock. "How could you suggest something like that!? What would Spike think?"
"I'm not talking about Spike. I'm talking about a dragon. Sure, Spike may be a dragon, but he's been raised by ponies his whole life. He wouldn't think of harming any of us. But there are other dragons that would have no such qualms about doing something like that. My point is this: would eating a pony automatically make the dragon evil?"
"Yes, it would!" Shining declared. "Evil is the intention of causing harm!"
"I agree, but only to an extent. I believe actual evil is the deliberate causing of harm that one takes enjoyment from doing. We could call a dragon eating a pony evil, but is it really evil if the dragon was on the verge of starvation and it was the only opportunity to eat it could get?"
Shining was about to protest, but Twilight cut him off.
"Is it evil if a pony steals an apple from a street vendor because they can't afford to feed themselves? What about if a pony kills a timberwolf in the Everfree Forest? Are they evil for killing that creature when it was trying to take their life beforehoof?"
"Okay!" Shining conceded in defeat. "Maybe his feeding in the past wasn't exactly evil, but I still don't think it's right if he did it."
"How can you say it's not right that he's doing what he needs to so that he can survive?!"
"Umm, excuse me?"
The sudden voice in the room caught everypony's attention, and all eyes turned to the changeling bound in restraints.
"I've never wanted to cause anypony harm. I-If I offered an apology, would that help any?"
Shining wanted to verbally accost the changeling, his building frustrations recognizing a convenient outlet set before them, but a golden aura on his muzzle stopped him.
"I cannot blame a living thing, pony or otherwise, for doing what is necessary for them to remain alive, even the more morally reprehensible actions," Celestia told Thorax. "With that said, I don't think an apology will be a cure-all for the animosity at the current moment, but it could be a starting point for us to move past it."
Thorax gave a nod and gulped. "M-May I step forward?"
Celestia gave a nod, and then gave one to her guards; a wordless order to allow him to step forward.
The guards in front looked to each other for a moment, but then bowed to the princesses and stepped aside, allowing Thorax to move forward. The changeling did so, one cautious step after the next, until he was near the base of the dais Celestia's throne sat upon.
Taking a few deep breaths, Thorax prepared to speak.
"I... Um, I'm sorry to anypony I've ever hurt. I never meant to do it, and I hope they can forgive me."
Thorax then turned and looked at both Shining and Cadance.
"I'm sorry about what happened with your wedding. I don't know what our queen was thinking, but I wish she had thought of something better than what she did."
Nopony said anything for a moment. Thorax hung his head low, unsure if his apologies would be accepted or not. After a few moments more, a voice did finally break the silence.
"You claimed to have seen Miss Twilight and her friends yesterday, correct?"
Thorax looked up at the princesses, finding both of them looking at him expectantly.
"I... I did."
"And this was in one of the circular common areas, wasn't it?"
The pony asking the questions was the lunar princess.
"If that's what those things are called."
"And you claimed to have been moved by their fight against the other changelings?"
"I was. I've never seen such cooperation before. The way they took care not to hurt each other and helping one another when they got into trouble. The other drones would never think to do that."
Luna considered Thorax for a moment before whispering something into Celestia's ear. Celestia considered it for a moment, then whispered something back to her sister. Luna thought over what had been whispered to her, then nodded and whispered back to her sister, who nodded in agreement before facing the changeling again.
"In light of the recent revelations presented by my student and what has been shown to me by conducting the very same tests myself and achieving the same result, I can say without doubt that you carry no desire to cause malice to my subjects."
"However, your need to feed on love from other creatures still makes you a danger in some capacity to them. With all of this in mind, my sister and I would like to extend an offer to you."
Both Thorax and Shining Armor looked at the princesses with open mouths. Neither of them believed what they had just heard.
"By now, you're quite familiar with Twilight and how eager she is to learn new things," Celestia continued. "Since much of your kind is unknown to us, and you are our best source for this information at the moment, I give you this simple offer: answer my student's questions about your kind, and I will permit to stay with her in her library in the town of Ponyville."
"There will be security considerations, of course. I will have a garrison of guards stationed there to keep watch of you, and you won't be allowed to go anywhere by yourself."
"To show this isn't a one-sided arrangement, I will add something to sweeten the deal, as it were. If the information you provide us is both sound and aids us in protecting innocent ponies and creatures from being harmed by your queen and any of the other changelings, I will consider granting you a full citizenship in Equestria after a year's time."
"My student will also do what she can to assist with your dietary needs, and possibly find an alternative that is a better option than what is currently available to you now."
"That is my offer to you. If you decline it, then you go back to being a prisoner. If you accept it and try to double-cross us, then you will receive a much worse punishment than just being a prisoner."
"So, in summary, I am willing to let you stay with my student, and possibly become a full Equestrian citizen, in exchange for all the information you can give us that will help us to defend ourselves from your kind. Thorax, do you accept this offer I am making to you?"