Error Sans stood in the shadows of the Everfree Forest, watching over the town of Ponyville as the sun began to rise over the horizon. While he watched a few ponies walk out of their homes early to get their respective businesses ready for the day, he began to wonder what kind of dangers were present in the modern world, considering all that he had faced alongside Celestia and Luna before an event known as "The Great Purge" which we will get into later.

Losing interest in the large town he lifted his hand off of the tree he was leaning against and began walking through the now tame forest of thorns with his hands in his pockets. His eerie presence keeping any creatures that still remained in the forest away from him as he ventured towards the Castle of the Two Sisters.

Upon reaching the bridge leading to the castle he immediately walked to the side of the bridge and began walking down the stone steps that led to the cave of the Tree of Harmony. He merely stood a few feet away from the glowing crystal tree, feeling it's cleansing energy surrounding him, but soon being pushed away by his own corrupt presence. No matter how hard the tree tried, it could not repair Errors body. "Strange to-to-to see the e-elements placed back after so many years."

He took a few steps forward and slowly placed a hand against its rough crystal surface, the tree immediately reacting to his touch and preventing any of his dark magic enter its systems, that was not what he was trying to do anyway.

"It seems s-s-s-s-stronger, like the elements-ments are closer s-somehow." He spoke to himself in interest. "I wonder wh-what's been happening-ing since I was l-l-last on the surface."

He took his hand off the tree and turned to walk away, but he stopped for a second as he looked back. He then noticed the new shapes of the element gems. After seeing the new look of the gems he smiled and walked away.

"Of c-c-c-c-course, new bearers." As he was about to place his foot on the first step he teleported back to the top of the stairs. "Now...lets g-g-go-o see what's up with-ith that mare."

As he walked forward he felt something click I'm the back of his mind, only causing him to grin widely as he sensed a mistake in reality.

A few hours later

Twilight and Starlight began walking towards Sweet Apple Acres, having promised to help Applejack around the farm while Big Mac had a personal day off, but only after being forced to have one by his sisters who insisted he needed some time to himself.

As the two were approaching the field they saw that the moon was rising, eclipsing the sun and causing the sky to go back. Twilight and Starlight looked to each other in confusion, if Celestia and Luna were planning something like this they would have been informed, something was wrong.

Suddenly though, Rainbow Dash came rushing over to the two. She couldn't slow down fast enough and crashed into Twilight. Starlight used her magic to lift the cyan mare off of the alicorn, allowing Twilight to regain her composure. As she was about to ask Rainbow what was wrong, the Pegasus yelled before she could even open her mouth. "Twilight, you need to come with me and fast!"

"Why? What's happening?"

"It's Nightmare Moon! She's back! And there is something seriously wrong with her, and not just in an insane way, but in a very, very strange way!" Rainbow exclaimed.

Twilight and Starlight looked to each other in shock before turning back to the panicking mare in front of them. "Well what are we waiting for, let's go stop her!"

Rainbow nodded and began leading them to the centre of town, where their old enemy had reappeared.

The trio reached the centre of town where the rest of the mane six were waiting for them, all with worried expressions. "Oh thank goodness you're here Twilight. It seems as though we may be in a spot of trouble." Rarity said uneasily.

"Dash said that Nightmare Moon has returned and that something was wrong with her. Is Princess Luna trying to take over Equestria again?" Twilight asked worriedly.

"No. I'm not." They all looked up to see Luna and Celestia flying down to them before landing with stern extensions on their faces. "This Nightmare Moon is not the one that had taken over my body, it is somethings far more sinister."

"I don't get it, what's wrong with her?"

Fluttershy looked over he shoulder and squeaked in fear. "W-Why don't you look for yourself?"

Twilight turned around and gasped at what she saw. It was Nightmare Moon, only far more terrifying than before. Her eyes were empty black voids and blue lines of liquid seemed to pour from them. Her body was distorted and her mane was glitching between black,mired and yellow. One other thing Twilight noticed was that around her body, the word 'error' flashed constantly. "What is she?" Twilight asked terrified.

"She's an error, a mistake in reality." Celestia explained, her expression unchanging. "She shouldn't even exist."

Twilight just continued to stare fearfully at the corrupt mare before them. "Aha-a-a-ahahahaaaa! Foolish ponies! The n-n-night shall last for all-all-all eternity!" She exclaimed in her glitched voice.

"What do we do?" Starlight asked Celestia who looked around for a moment before setting her gaze onto a rooftop and smiling warmly.

"We don't do anything, we just sit back and watch." Everyone looked at her in confusion before following her gaze, seeing a silhouette on the roof of a house.

The figure disappeared for a moment before reappearing in front of the group. Error Sans held out his hand and summoned a Gaster Blaster, a large black dragon/goat skull with one gliding yellow eye. It opened its mouth and a large beam of energy was shot towards Error Moon at blinding speeds. Error Moon managed to dodge the attack but soon found herself bound by multiple blue strings. Looking back she saw the strings were coming from Errors fingers as he pulled them to tighten the hold on the mare.

"Took you long enough." Luna said jokingly to her old friend.

"P-P-Please, I was here way before either-er of you." Error countered playfully while still keeping his hold on Error Moon.

Twilight and the others just looked to Error and the princesses in shock. "Princess, who is that?" Fluttershy asked Luna quietly.

"That is our good friend Error Sans, you need not worry everypony, he's on our side."

Error just chuckled. "I-I-I-I am on nobody's s-side, I just do-of things because I want to. It j-j-just so happens that he-helping you is one of t-those things."

"Oh I totally believe you, real convincing anti-hero persona you got there." Celestia joked, causing the mares present to just stare at her in shock, wondering how both princesses were acting so casually in such a dire situation.

Error shook his head and returned his attention to Error Moon who had cut the strings with her magic and stood to face get new opponent. "W-Well, let's get this o-o-over with. But before-fore we do-o this, let me ask y-you something." Error Mokn just looked at him questioningly as he closed his eyes and placed his hands in his pockets, before opening his eyes again to reveal dark voids much like her own. "D-Do you wanna ha-have a bad time?" I'm not sorry, I had to make him say it sooner or later.

Author's Note

As usual, feel free to point out any mistakes I may have missed. Took me a bit longer to get this out.

Now if you'll excuse me, now that the chapter is done...I can finally go to sleep.