Princess Celestia stared at the group of ponies that came into her rooms, but what got her attention was the two monsters with them. Black and filled with holes and sharp edges, she wanted to shudder in revulsion at them. The way the changelings fawned on one of the ponies, she realized that they weren't ponies at all, but more monsters.
"Princess!" Shining rushed forward, her heart filling with horror; Princess Celestia looked like she had collapsed on the bed, and there were multiple puncture marks at her neck. "How long have they had you like this?"
"How long?" Thorax turned to Obsidian Gleam. "And how often is she being bitten?"
"M-Morning and night, Your Majesty. And she has been like this for two days." Obsidian cowered, expecting her new queen to be angry. With her little ears tucked back, she braced for a strike that never came.
Thorax reached a hoof out and pulled the cowering changeling against her. A rush of relaxing pheromones had Obsidian relaxing a little while Thorax stroked her crest. She looked over to where Shining stood beside Celestia's bed.
"Monster…" Celestia fought to get the word out. She glared up at the not-pony beside her. Confusion was eating at her anger, however. When they lifted a hoof up and pressed it to her cheek, she felt softness, warmth. The not-pony actually cared for her, and the realization of that broke at some of her anger. "Who…?"
"Shining Armor. The real Shining Armor. They foalnapped me in Ponyville, bit me…" Shining gestured to Celestia, "and hauled me off to their nest. I'm not a pony anymore. I'm a changeling, but that isn't going to stop me doing what is right."
Celestia stared at the "princess" standing over her. The look, the way she acted, it all spoke of a mare. Opening her mouth, she struggled and fought with her paralyzed vocal cords to get the words out that she wanted. "Protect… Equestria…"
"With my life, Your Highness." Shining bowed her head to Celestia. "We have spoken to Princess Luna, she sent us to guard you. The castle is wormy with changelings loyal to Queen Chrysalis, but we have a secret weapon." Turning to Thorax and Sunset, she smiled and looked back. "There is going to be a long talk, and I know you have a lot of questions, but tomorrow we fight for Equestria. Please, Princess, focus on regaining your control."
Holding Shining's gaze with her own, Princess Celestia felt certainty that this actually was Shining Armor, and she was sincere. A sudden thought came to her. She felt agitation swarm over her body, fighting the poison keeping her from moving as she wished. "L-L-Luna… Protect Luna…"
"She is aware of them." Shining felt a gnawing unease that Celestia was right. 'Of course she's right, she is Princess Celestia,' her thoughts startled her, and Shining realized how easily she had discounted Celestia just because the Princess was incapacitated. Nodding, she turned. "Queen Thorax, Sunset, get Flash to lead you to Luna's quarters. I can't believe I was so stupid to believe they wouldn't do something to her."
On the bed, Celestia's mind froze completely for what felt like forever to the alicorn. She stared at the mare Shining had called "Sunset" as she turned and left the room. Sunset Shimmer. The name brought sorrow and a little confusion. She added a new set of questions to the list she was formulating in her mind. A brief pang of sorrow filled her, for the nearest pony when she could first talk again.
Vinyl nodded to Shining and slipped out to escort Thorax and Sunset. She smiled when three of the Crusaders fell in too. "This just got so complicated." She knew the way to Princess Luna's quarters, but maintained the guise of following Flash Sentry along. She perked her ears and glanced to the three "guards" following her.
"We've got your back." Apple Bloom marched along, and her training in the changeling hive held her in good stead while her thoughts raced. "What have we got your back from exactly?"
"They could be making a move to replace Princess Luna before the ceremony. They could be simply putting her out of commission like Princess Celestia." Vinyl channeled her Shining-side to get the worst of the things out of her system. "Or it could be nothing."
In the more highly populated sections of the castle the group kept quiet, but leading to Luna's wing traffic thinned out again. "There she is." Thorax spotted Luna at the other end of the hall, and the Princess was just entering her own quarters. She couldn't recognize the two Royal Guards at the entry to the Princess of the Night's chambers, but she knew something was wrong when both turned and entered the room behind Luna.
"Something's wrong…" Vinyl jumped forward into a gallop, and was joined by Flash in her mad dash for the Princess. Reaching the door, Flash crashed into it, heedless of harm to himself. Vinyl blasted it, but neither attack did more than buffet the doors.
"Out of my way!" Sunset had discarded her disguise, and threw her magic into one of the more iconic of changeling attack methods. Power arced before her, and she streamed forward like a missile at the doors.
Thorax and Vinyl rushed inside, leaving a dazed Flash and Sunset behind them. Thorax watched the scene of her greatest horror playing out before her. She was paralyzed, staring at the changelings standing over Princess Luna.
"No…" Vinyl saw the pair of glistening fangs on one of the changelings moving back from Luna, and could see a little movement on the bed. "NO!"
Luna couldn't move. The first bite had taken her fight away and the second had completely stolen her limbs from under her. The orb laying before her face was broken and open, the green goop inside having leaked onto her midnight satin sheets.
Scootaloo flew through the doorway and didn't stop. Unlike the others, he took in the situation and knew that it was up to the Crusaders to stop this. "Get 'em!" He slammed a shoulder—that had suddenly grown spikes—into the nearest enemy changeling.
With room to get in close now, Sweetie Belle lit his horn and shoved the second nasty changeling aside. "A worm! Apple Bloom, get the worm!"
Luna's mouth was gaping open from her attempt to bite one of the changelings. The grub inside the egg before her disgorged itself onto the bed and started to inch closer. A cold sweat rushed over her; Luna didn't know what the thing was, but the way it was inching towards her mouth made her sick to her stomach.
Bundles of nerves that had no mind to them, yet, drove the newborn parasite on. It could sense the breath of its host near, and with sight that could only detect warm things, it aimed itself at its new home.
Landing on the bed, Apple Bloom watched the worm get catapulted into the air by his bounce. "Ah got it." He aimed his horn at the parasitic larva and blasted.
"You missed!" Scootaloo watched the worm land on Luna's shoulder. Just as he was about to line it up, the changeling he had crashed into regained their composure and tried to shove him away. "Ugh, help!"
Sweetie Belle was caught up fighting the changeling she had picked a fight with. Her training came to the fore and he burned energy shapechanging thick protective plates onto his body. Tactics swarmed in his head, but he knew they out-numbered the changelings, so defense was the best strategy.
Warmth at last! The parasite could feel its host's body under itself. A particular spot stood out like a beacon, but it was deep within its host. The parasite set its head against the warmth and started to bite.
Thorax finally broke the spell around her and stepped forward. "Stop this." Her words went unheeded by the brawling changelings, but the target of her command heeded it. The grub, mindless and full of potential, had halted as its mouth-parts had sliced a hole in Luna's shoulder. "This mare is not for you."
Apple Bloom gave a groan of relief as he watched the parasite levitate up and out of the wound it had made. But he pulled his eyes away from the green glowing worm to his fellow Crusaders. "Git off'a him!" This time his blast made contact, and sent the changeling fighting with Scootaloo flying.
Jumping back, Scootaloo surveyed the situation. Lowering his head, he blasted the changeling Apple Bloom had forced back with a good concussive blast that had them seeing stars. He looked back at Luna, and saw the terrified princess looking up at Thorax with one wide eye. Thorax held the parasite in her magic, and was slowly lifting it away from Luna. "Okay, things are under control there…" He swung around to look at Sweetie Belle.
"Bad buggy!" Sweetie's outrage overrode any actual anger. He was shocked that anypony or anyling would dare harm a princess. "You will not be naughty!" One of his heavily plated hooves lashed out and tripped the changeling he was engaged with. "You almost hurt Princess Luna!" Another kick—in just the right place—had the downed changeling seeing stars. "And you will be nice to everypony!"
"Sweetie?" Apple Bloom left the one defeated changeling and tried to get his friend's attention. "Sweetie Belle, it's okay. Queen Thorax got the worm, we were in time."
"H-How did you get here?" Luna's mouth was working again; her system was fighting the poison off quickly. Struggling to move, she realized she hadn't quite gotten enough movement to do that yet. "And what is that thing?"
"This," Thorax held up the grub with her magic, "is a changeling larva. Left to its work, it would have burrowed into you, grown inside you and become another you." She closed her eyes a moment and squished the larva's head. The act was sickening, and she placed the blame squarely on Chrysalis. "You would have been turned into just another changeling nymph."
"Are you okay Princess Luna?" Sweetie Belle had snapped from his outrage at the changelings' actions, and turned to Luna. "Is there anything we can do?"
"You can…" Luna bit back on what she was going to say. "Please guard me while I recover." It was all she could think to ask, and the only thing she needed right then. "Is my sister safe?" Any hope of her maintaining her aloof demeanor by using her royal plural pronouns was shattered, but what shocked her most was when her apparent saviors dropped their disguises. "Foals?!"
"We're the Cutie Mark Crusaders!" Apple Bloom puffed her little chest out and chirped her wings in pride. "And we're nymphs, not foals… not anymore." A lump caught in her throat.
"Sowwy we didn't get here sooner, Princess." Sweetie crowded in around Luna, along with her friends, although being nymphs it was much less crowding than when they were Royal Guard. "Are you hurt? Can you move? Oh, it hurt you…"
The assault of questions would have infuriated Luna if the changeling asking them wasn't so adorable. Pain flared in her shoulder, and she kicked and flapped her wings in agony. "Uggh!" Rolling from the bed, she landed on wobbly hooves. Panting hard, she turned her head and looked at the hole in her shoulder the grub had started to enter.
"If it had gone deeper I could not have stopped it." Thorax stepped up behind the three Crusaders. "On behalf of my kind, I apologize, Princess Luna." She dipped her head and bowed to the Princess of the Night.
Furious as Luna was, she knew that her saviors were not part of the conspiracy. She closed her eyes and counted slowly, forcing a nearly limitless anger back down. "Why were they doing this?"
"If it had gotten inside you a new toxin would have gone to work. You would have been pliable, weak to suggestions for action. Your magic would have faded to a speck, and you would have begun changing." Thorax levitated the grub's body into a nearby rubbish pail. "One of them would have likely taken your appearance and attended the wedding in your place."
"Who are you? Why are you telling the pony our plans?!" Lifting his head from where one of the "Royal Guard" had laid him out, one of the two drones glared at Thorax. "And you!" He glared at the Crusaders. "I can't believe I was beaten by nymphs!"
"So that was the plan?" Thorax turned her head towards the recovering drone, and started to disseminate a new pheromone. "Please, tell me everything about what Queen Chrysalis had planned for Princess Luna."
Eyes widening, the captive choked and coughed, and felt his brain splitting in two. Struggling between his orders and a command he now couldn't resist, he whimpered and lay back down on the floor. "I was supposed to disguise as the Princess, one of the others was going to disguise as the other one, and together we would have 'fought' with our Queen. We would have lost, bowed down, and let her claim Canterlot."
Luna blinked at the suddenly forthcoming changeling. "How do we know you are telling the truth? You seemed more than capable with lies moments ago…"
"He can't lie, Your Highness." Sweetie Belle's shyness hadn't returned yet. She was still buoyed up on the excitement of the fight that she would have talked about nearly anything. She realized then that what affected the drone was affecting her too, only she didn't care. "He can't tell anything but the whole truth now."
"All the truth." Apple Bloom couldn't stop herself from cutting in to clarify.
"And why can't he tell anything but the truth?" Luna looked between the apparently knowledgeable nymphs. "What is going on?" She directed her gaze to Thorax.
"I am their queen now. I… made sure they told the truth." Thorax reached a hoof out to tickle the head-fins of the three Crusaders. "Sorry if it got you girls too."
"That's okay!" Apple Bloom beamed. "Ah don't lie to princesses, it's a family thing." She nodded with a solemn look on her face.
"That was never a family thing!" Scootaloo poked Apple Bloom in the shoulder.
Nodding and sticking her long tongue out at Scootaloo, Apple Bloom ignored the poke. "Well it is now."