In the streets of the Crystal Empire, behind a building, in a dusty alley where no pony had set hoof since the Empire's return, as it was a cul-de-sac with nothing interesting in it, a unicorn, who'd found herself there after having decided that her instincts were far more trustworthy than a map, was having a conversation with somepony she'd found there. Or what was left of him, anyway.
"So... how did you end up as a horn, exactly?"
"Well, it's a long story, but if you want to I can-"
"No, no, I have no interest in it," Trixie replied, cutting off the horn lying on the ground in front of her. She hadn't listened to Starlight's boring explanation of the Crystal Empire's history before their visit, and she had no intention of listening to his story if it really was long.
"Okay then," the horn replied. "Tell me more about yourself. You said you're a great and powerful magician, did you not?"
"Indeed I am! The Great and Powerful Trixie is the greatest magician in all of Equestria!" Trixie struck a dramatic pose, which went unnoticed due to the horn's lack of eyes.
"Are you sure? Because I don't feel that much power radiating from you."
Trixie frowned. "The Great and Powerful Trixie would gladly give you a display of her powers, but you appear unable to witness her greatness. Rest assured, though, she is incredibly talented."
Sombra sighed. Years spent as nothing but a disembodied horn, and he had to be found by that pony. At least she was a unicorn. "Would you not like to become truly great and powerful?" he asked in a deep voice.
Trixie drew back. "Are you suggesting that I am not already great and powerful? Watch your tongue-err, your magic-sound-producing-whatever, horn, or Trixie will leave you in this alley."
Sombra would have smacked his forehead with a hoof, had he still possessed any of the two. "I'm sorry, what I meant to say was: would you not like to become even greater and more powerful than you already are?"
Trixie walked back towards the horn. "Well, in that case, yes, I would like that. Not that I need it, mind you, I am already sufficiently great and powerful, but I would certainly enjoy an addition to my magnificence, even one as small as the one you can give."
"I will personally crush you under my hooves once I regain my body."
"What?"
"I will gratefully aid you in remaining the greatest magician in the land. Now would you please pick me up and allow me to merge with you, so that I may increase your already immense magical reserves?"
Trixie nodded. "Of course," she said, picking Sombra's horn up in her magic and bringing him near her. She then had a thought and stopped. "You're not going to corrupt me with your dark magic, turning me into your servant and rendering me an evil creature bound by my ever-growing desire for power, right?"
"Um... No?"
"Perfect!" Trixie replied, then she brought Sombra's horn in contact with hers.
The small crowd cheered as Trixie turned a bouquet a flowers into birds.
"You know, I hadn't expected her to be this good by the way you'd described her shows," Sunburst said to Starlight, turning to face her and making sure that nopony else heard him.
"I didn't think she would be this good," Starlight replied. "She must have practised in secret for this visit."
Shining Armor and Cadence clapped from their seats, Flurry Heart, resting between them, doing the same.
"And now, for her next trick-" Trixie brought her hat down with a sweeping motion "-the Great and Powerful Trixie will steal away all of your magical powers!"
Everypony looked at her with confused expressions.
From within Trixie's hat a series of dark, shadowy tentacles emerged, each one of them latching itself onto the horn of a different unicorn or alicorn in the room.
"Trixie, what-" Starlight began to speak, but was cut off by a sudden spike of pain.
In a few seconds, all the presents except for Trixie were on the ground, writhing in pain, as globes of energy travelled through the tentacles from their horns to Trixie's hat. After a short while, the tentacles retracted, leaving behind colourless husks of barely alive ponies, drained of all power.
A cloud of swirling darkness began to form around Trixie's hat. The object began to levitate on its own, the shadows around it collapsing towards the centre. Red bursts of lightning started to emerge from the black core of energy. Finally, with a loud bang and a flash of light, the hat fell to the ground in a pile of dark smoke, and King Sombra emerged from it, laughing.
Trixie smiled. She looked at the defeated bodies of her friends, at the powerless remains of two alicorns, at the unicorn in front of her, maniacally cackling, at the remains of dark magical energy slowly drifting away. Her smile faltered and she assumed a mildly concerned expression. "Wait, did you use me for something evil?" she asked.
Sombra stopped laughing. He looked at the bodies of his enemies around him, who he had just deprived of all magic, then at the unicorn in front of him. "What do you say?"
Trixie stroked her chin, thoughtfully. "You... did? I think. I'm not sure though."
Sombra, now having both a hoof and a forehead, proceeded to have them meet. "How did a pony this clueless get to be a guest at the royal family's table, anyway?"
"Well, maybe they just appreciate my talents!" Trixie replied, pouting and turning her head to the side.
"We only invited you because you're Starlight's friend, and she wanted you to come. And we only invited her because she's a friend of both Twilight and Sunburst," Cadence said from the ground, slightly lifting her head.
"Oh, it seems I haven't drained you properly," Sombra said, before sucking away the last remains of magic from the alicorn.
"Wait, you are evil!" Trixie burst out.
Sombra stared at her. "Seriously?" He then teleported in front of her, blocking her movement with his magic.
"Are you going to mind control me into being your servant?" Trixie nervously asked.
"No."
Trixie gave a sigh of relief. "Thanks. I'd promised Twilight I wouldn't let myself get corrupted by evil powers again."
"I'm just going to drain your magic away."
"Oh. That's bad, right?"
"Not if you're me."
Trixie gulped. "Well, at least Twilight won't be mad at me. Right Starlight?"
Sombra turned to see Starlight slowly crawling out of the room, and levitated her back.
"Oh. Sorry."