"What? Where has she gone?" Twilight asked, surprised by the emptiness of the room.
"I made sure no-one left. And I didn't see the flash of light of teleportation around the door." Rarity recounted.
"I suppose we should investigate." Twilight suggested, walking into the room.
Scanning the room, Twilight began to focus on the large mirror. "Wait, haven't we seen a mirror like this before? One of the ones that can travel between dimensions?"
Rarity stood next to her. "Now that you mention it, yes."
"I can only assume this is the one for that backwards-universe." Twilight said "You know, the one with the good king Sombra and evil Celestia." Twilight said "Mainly because if the other universe-mirror from the Crystal Empire went missing, we would have heard something about it."
"But wasn't that sealed off?" Rarity asked.
"I thought so. We must see Celestia about this."
"Welcome to my home Trixie. I am afraid this place is isolated from most of this world." The figure spoke.
"Who are you?" Trixie asked, "Truly?"
"You may know me as your 'Phantom of the Gala'. Maybe more as another stallion, though not the exact one you know." The figure, the phantom, replied.
"Other stallion? Who? Not the one Trixie knows?" Trixie queried.
"You may understand in time." The Phantom replied vaguely, obviously dodging the answer. "Allow me to show you my quarters."
"Alright." Trixie sighed, relenting.
The phantom lead Trixie down a large corridor, strangely reminiscent of the corridors of Canterlot Castle. It was strange, in that respect. Windows were shattered and boarded up, the carpet on the floor was torn apart and grand chandeliers shone barely any light, despite the fact they were fully lit up. Trixie allowed herself to study her guide further, taking in as many details as possible.
His mane was kept up in some semblance of a regal hairstyle, though various strands of hair had fallen, covering his face. His horn parted his hair above a worn, blue band of silk with a golden button placed in the centre. His eyes seemed to be a cross between a red and brown colour. His cloak was obviously from some sort of royalty, though it didn't look like something Celestia would have in her castle. Under his cloak, hints of polished, dark-grey armour shined in the low light.
"How long have you been here?" Trixie asked.
"What feels like many lifetimes." The figure replied, his voice near-emotionless, almost as if he were hiding something. "I could not tell you exactly."
The unicorn came to a halt before a large set of wooden doors. He lit up his horn and opened them, allowing view of the inside. It was a throne room, remnants of stained glass windows, almost entirely mirroring those of Canterlot Castle.
"What? What is going on here?" Trixie asked, her eyes focusing on one of the windows. She ran up to it and rended the board from the frame.
"Stop!" The Phantom yelled, using his magic to grab onto her and trying to pull her back.
"What is out there?" Trixie questioned.
"Trixie, you may not understand." The phantom replied. "Though I suppose I must relent, for you will be inquisitive. You must not question this, alright?"
"Alright." Trixie replied.
"This is not your world." The figure spoke. "This may sound utterly absurd, but this is an alternate reality, of sorts."
"What? You mean that mirror was some sort of portal? You lured Trixie to another world?" Trixie asked.
"Yes."
"Why?"
"I find you captivating. I merely wished to show you a glimpse of my world."
"Take Trixie back."
"Sorry?"
"Take Trixie back. Now!"
"I only ask you wait to see what I have to show you." The phantom said. "Then you will return."
"Before I agree, one question."
"What is it?"
"Who are you?" Trixie asked once again, her horn lighting up and ripping the mask off of the phantom's face.
The sight Trixie saw caused her to faint.
The phantom stared forward in horror, green magic beginning to flow from his eyes. He grabbed the mask from her, forcing it back on quickly. "Trixie, you do not know what you could have started." He whispered, the magic fading.
"I feared this may happen once more." Celestia said to herself, Twilight and Rarity having just left her room. "I should have stopped it when I began receiving those letters. Nothing good could come from it. I hoped he had changed, but perhaps he hasn't."
She scanned over the papers on her desk, lifting a stack of documents, revealing a sealed letter underneath, 'Dear Princess Celestia' written on the front. She had received this today. She broke the seal and retrieved the parchment from within and laid it out on the desk.
'Dear Princess Celestia,
I thank you for fulfilling my demands so far, I can see I may have been wrong in my judgement of you after your previous acts, and I apologise. I hope you can keep my appearances a secret, for I am only here for one reason; one reason which you understod once, as you once partook in a similar act, those centuries ago.
If you refuse, I do understand, but do tell me so before you do go revealling this to the public; I would like to know if you wish for your history to be repeated. I surely do not.
Yours faithfully,
King Sombra.'
"I knew it."