Hivemind Control

There was a feeling of numbness as Twilight descended the stairs. Today had been a significant amount of stress for her, and her mind was reeling from all of this new information. Certainly, while serving as the only princess in Equestria, she'd had some aggravating days, but those were nothing compared to this. In the royal courts, she could recess the case until the next day if it became too much, and she had the comfort in that her decision would be carried out. This time, the decision was not hers, and rather than recalling old information, she was being filled with new information that she was unable to work with. She'd wanted to learn what was going on, but what information did she learn today that would help her escape? Only where to find Applejack and Pinkie Pie, and that the princesses would be needing some type of antivenom that she could not name. She didn't even know where the door leading outside was, or if there even was a door.

She barely noticed the tug against her lead when it was time to cross her bridge. The level was the same as she had awoken from, so she was returning to her bedroom without going to see Fluttershy. Perhaps it was for the best. She wasn't in any mood to learn more today. Or... tonight. Being underground with the only light being from the mushrooms meant that she had no idea what time it was. She hadn't seen a clock for the entire tour, so the only indication for the time she had was that she was tired, hungry, thirsty and sore. Those might indicate any time of day, but right now, it told her to find a bed and sleep. Being directed to a bedroom, she did not fight back. She had neither the energy nor drive.

The room was exactly as she had left it, save for one of the guards outside having a slightly different face. It was likely a second changeling on a different rotation. They were chatting nonchalantly amongst themselves until Twilight and Cercus approached, at which point they stood at attention.

As soon as they were in the room, Cercus took off Twilight's harness, letting her walk free from him. She moved across the room and flopped down on the bed. As tired as she was, she wasn't quite in a state where she could fall asleep. Her mind was buzzing with a dull hum as she tried to piece together all she had learned today. There was a lot to unpack.

Suddenly, the bed moved, tilting as a new source of weight lay down on the other side of the mossy mattress. "What do you think you're doing?" she asked, turning and glaring at Cercus.

"There's something I have yet to mention," said Cercus, laying one hoof across his abdomen and tucking the other beneath his head. "You and I are sharing a bedroom. Moreover, we will be sharing a bed."

Twilight sneered. "Don't you have your own room to sleep in?"

"I do."

"Then why don't you go there?"

"I am already here." He turned to look at Twilight. "I am not in your room. You are in mine."

Twilight looked around the room once again. It was just a bed and a chair. "Well, you don't do a very good job decorating it, do you?"

"No, I don't. I spend my days outside of it, doing work. I come back to sleep in it, and that's only if I'm near enough to justify coming back. It's two and a half days to Canterlot with no breaks, and that's assuming I'm not spotted, so having a temporary house in town was crucial. By the way, thank you ever so much for securing my lodging in Ponigsburg."

Twilight sat up. "I never sent you to Ponigsburg."

"Oh no?" Cercus quickly shifted into the form of an earth pony, slender with broad shoulders and a dark green coat. His orange and red mane was slicked back, and his eyes had changed shape, but were still blue. "You certainly wouldn't let me tend to my nuts for fear of upsetting Luna."

Twilight's eyes went wide. "You're Cosmo," she realized.

"Actually," smirked Cercus, shifting once more to a pegasus, his short dark brown mane drifting just to his neck and no further. "My little swimmers have taken stops in half of all princesses. All except you and Cadance." As he smiled, he shifted from Dip back into his changeling form. "Mind you, none of the eggs in the hatchery are mine. After escorting Luna here, my focus was entirely on watching you, and waiting for the right time to strike. And of course, I couldn't let your little friends pose a threat, so they had to go, too. Finally, after knocking you out, I brought you here, and, let's be honest, this will be the first time I've actually slept here since before you separated the princesses."

Twilight huffed. "You've been right under my nose this entire time?"

"The whole time, yes. Ever since this place was only a few layers tall. I was even the one who orchestrated the original ambush on Luna. All I needed was a tiny prick with a blade, but to avoid suspicion, I staged the whole thing as a bandit attack."

"But Celestia was never stabbed," argued Twilight.

"Too true. But the poison is excreted by a parasite, so if we can, say, disguise it as spice and let it grow and multiply inside her intestines, her body will absorb the toxin just as easily. The eggs look like ground nutmeg, allegedly taste of clove, and can easily be hidden in a plate of waffles for Celestia, or spiced jelly for Cadance. And while I wasn't present for Cadance's transition, I did convince Luna to poison Celestia."

"How?" demanded Twilight. "Why?"

"Celestia was distrustful of me. I had to have Luna do it because she wouldn't trust any food I gave her, and poisoning a member of the kitchen staff to help me only complicates the matter. A quick shake into the batter, a stir, and all is taken care of."

"Again, how did you convince Luna to do this?"

Cercus smirked. "The venom of a wiggleworm makes the victim susceptible to changeling pheromones. Combined with the seminal fluid of a changeling, it heightens the desire to please them. It also makes their love less flavourful, but if its an alicorn, you can accept that loss in exchange for the ability to lay eggs."

"Is that what you're going to do to me?"

"All answers in good time," he smiled. "For now, you should rest. You look tired."