Author's Note
Just a disclaimer: this story contains swearing. If you don't like that then don't read. And if you do still read, I kindly ask you to not be mean about the swearing to either me or anyone else.
Also, I know show-wise, Nightmare Moon is reformed, but for this story, she is not.
Enjoy! 
What The Fuck!!
Somewhere beyond the grounds of the redone Changeling Hive, three of Equestria's greatest are sharing a chat. They talked about various ways to take down their enemies, they laughed and mocked each other's defeats, and they argue about many things. The three villains, individually, are known as Nightmare Moon, the opposer and sister to Equestria's monarch, Chrysalis, the former queen of the Changelings, and King Sombra, the king of shadows and darkness.
"Hey, Moon," Chrysalis said, giving Nightmare Moon a sideways glance. "Remember the time when this so-called king died at the claws of a baby dragon? Wasn't that simply hilarious?"
Nightmare snickered.
Sombra scowled darkly and delivered Chrysalis a hard shove all the way to the nearby pine tree. Chrysalis yelped as she collided with the trunk. She staggered for a minute to regain her composure. Then she returned Sombra's glare. "Bitch," she hissed.
Sombra ignored her insult and went to Nightmare. He made an impression of bitch-talking about Chrysalis in a low whisper. "Hey, Moon. Remember when this whinny brat lost her own hive to a traitor? That sounds humiliating."
Chrysalis lunged in an attempt to push him. Sombra simply stepped aside and Chrysalis went straight toward a thorny bush. "OWW!!" she roared.
Nightmare snorted. "Both of you have no brain cells. And if you do, they're not working." She stuck her nose in the air and used her wings to throw the king and queen off balance. '
Sombra and Chrysalis exchanged a raised-eyebrow face. They both nodded at each other before Sombra trailed after Nightmare saying, "Oh, and we couldn't possibly forget you being jealous of your sister because she's hotter than you." He finished with a smirk.
Nightmare halted midstep. She whirled around and ganged up on the stallion. "How dare you!! That is absolutely not why I tried to dethrone her. She hogs all the fucking attention and leaves me in the dirt!!" Spit was flying out of her mouth as she shouted.
Sombra chuckled and leaned closer to Nightmare. "Exactly. She's sexier than you. Ponies love her more because she's far more desirable. I don't think ponies would even think about liking a whinny, attention-wanting bitch."
Chrysalis turned into Nightmare Moon. "Oh, please ponies, love me. Please love me." She switched back to her real self and burst out laughing. "That sounds ridiculous."
"RRAAAWWW!!!" Nightmare roared in fury. "HOW DARE YOU PIECES OF SHIT!!!!" She was about to do something really bad when a tapping sound caused all three villains to stop.
The sound first tapped before switching to a scraping sound. A low hissing followed. Chrysalis looked all over with wide eyes. Nightmare Moon was checking the sky with a mildly startled expression. Only Sombra displayed zero percent fear and, in fact, stared from Nightmare to Chrysalis and vice versa with amusement.
The hissing sound turned into a low, guttural snarl. Chrysalis and Nightmare moved back and placed themselves behind the only male in the group. Sombra stomped at the dirt below. "Whatever you are, it would be the biggest mistake one could possibly make if you decide to mess with me or... ahem... the idiots cowering behind me."
Both the girls glared at him. He either ignored them or didn't notice.
The snarling stopped. A deep, strangely-familiar voice spoke. "Oh, but I'm certainly a creature that doesn't need to worry about that for I am the most powerful creature in Equestria. You can cast curses, mind-control ponies, conquer whole kingdoms alone, and grow magic-proof crystals. Chrysalis can shapeshift into anything. Nightmare Moon can move celestial bodies with her magic. But me? I can rip the very fabric of reality and create a whole new dimension where the sun turns into cheese and melts. This can be a riddle for you. Who am I?"
Chrysalis and Nightmare Moon exchanged a flabbergasted look. Sombra snorted and stared ahead. "Please, is that so hard to guess, Discord? If you wanted to make this a guessing game, you need to try harder."
In seconds, Discord's serpentine form sprang into view. Before Sombra, Chrysalis, and Nightmare Moon could even move, Discord snapped his fingers and a bright flash blinded their visions.
It went on for... one second? Two seconds? Three?
When the light cleared, every pony and creature was able to take in the result.
First thing, Discord burst out laughing like a complete maniac. Though, you couldn't blame him. The sight one would witness, would do nothing but make you want to laugh your fucking ass off.
The three villains' colors were swapped.
Nightmare Moon had Sombra's colors and design.
Sombra had Chrysalis's colors and design.
Chrysalis had Nightmare's colors and design.
Their reactions followed.
Nightmare Moon glanced down at her body. "Wait? WHY IS MY COAT GREY!!???" She looked at her back. "Since when was that cape there? Since when did I wear silver armor? WHAT THE FUCKING FUCK HAPPENED TO MY HORN!!!??"
Sombra didn't need to look at himself to know he looked hideous. "What the fuck," he said. He turned rage-filled eyes at the still-laughing Discord. "Discord, what the fuck!!??" The king glanced at himself with alarm. "Ew, gross, disgusting."
Chrysalis was feeling at her starry mane for five minutes straight. She didn't say anything for a long time. Her eyes were possibly wider than the Sun.
"What?" she mustered out.
Then all three of them were shouting at Discord. "HOW DARE YOU!!!????"
"I swear I'll kick your ass!" Sombra snarled. "You conniving, stupid cock!!" He channelled a powerful blast of magic on his horn and hurtled it in Discord's direction. Which Discord dodged, obviously.
Discord let loose his third wind of laughter. "You all should see the looks on your priceless, hysterical faces. You look ridiculous. Simply ridiculous. And it's not like you can do anything about that. You're practically grade one level next to me."
Chrysalis shook with anger. "I hate that you're right!" she spat.
She nearly toppled to the ground when Sombra smacked her on the side. "What do you mean he's right?" He proceeded to roar and charge at Discord. Discord's eyes widened while taking off.
Chrysalis and Nightmare exchanged a nod. "After him," Chrysalis agreed.
The two females ran behind Sombra. All three of them intended to beat Discord's poor, unfortunate soul.
