Image imported from derpibooru
Original Description:

-2AM at Spongebob’s Pineapple-

In the Living Room, both Daybreaker and Doofenshmirtz were sleeping on the couch while Kori and Cozy were sleeping in their sleeping bags… Cozy then dreams about her Dark Past… basically, her dark past was merely about draining magic from the entire school, teaming up with Tirek and Chrysalis, and almost causing destruction in Equestria. And being trapped in stone was the Mean 3’s punishment for all of the destruction and/or property damages to the castle in Canterlot.

Before Discord, Celestia and Luna can turn the Mean 3 into stone, the flashback stopped. Cozy paused but realized that the laser was stopped.

“That never supposed to happen.” Cozy said, touching the laser in curiosity. But a curtain ‘SWOOSH!’ from a shadowy figure caught her attention. Then the filly started to go follow it.

As she follows it, it lead her to a strange castle. As she went inside, the first thing she saw was figures of the Mane 5 on the table, Pictures of a familiar Shadow Alicorn, one of them shows the Alicorn with a Unicorn named Misty as a filly, and the amulet that Misty wears to call the Shadow Pony. She sees them as she passes by them. She saw the shadowy figure again. This time, it reveals a cloak and a bit of magenta on the hooves as it enters another room. And Cozy starts to go after it.

Then she enters the throne room. The Filly starts searching around for that shadowy figure and all Cozy sees was the throne.
“Goly, that’s where it sits.” Cozy quietly said to herself, seeing the details on the throne.

‘Why didn’t you come back?’ said the shadowy figure. Cozy turned around and sees the figure in revealed now.

Cozy gulped before saying, “Well, I think you’re being-”

‘Suspicious?’ it said. as it uncloaks itself, it reveals a familiar alicorn mare in magenta, somehow that figure was Opaline Arcana: the soon-to-be future ruler of equestria. She continued, “We already know that.”

“We?” Cozy asked.

“YOU COULD’VE JUST LEAVE HER ALONE, COULD YOU!?” The Yellow Rabbit yelled, standing right behind Opaline this whole time.

“Afton?!” Cozy yelled.

“Yellow Rabbit?” Opaline said, “You know what to do.” Then she exited out of the room with an evil chuckle that shook Cozy to the core.

“Wake up, children!” Afton said as the portals opened, “I found somepony for you to play with!”

Coming out of the portal was Freddy, Bonnie, Chika (holding Mr. Cupcake) and Foxy. Cozy was really scared to think about it.

“This is gonna be so much fun!”

“Afton, I’m scared!” Cozy said, she can really feel her hooves shaking.

“Well, you should be!” Afton said, cleaning his knife with his fingers, “Farwell, Cozy Glow!”

“No! I don-”

(SHING!)
…

“AAAHH!”

Cozy finally woke up from her nightmare. Then she looked around and sees Kori, Daybreaker and Doofenshmirtz still asleep. She sighs in relief, got out of the sleeping bag and went to Puzzle.

-In Spongebob’s Room-

Cozy quietly opens and closes the door behind her when she got in.

“Um, Puzzle?”

“Huh?” Puzzle said, woken up from her sleep, “Oh. It’s you, Cozy. What’s wrong?”

“I have a bad dream.” Cozy said with a frown on her face. Then she talked to Puzzle about everything, including Opaline, Afton and the four animatronics from the old pizzeria… including her dark past, which it still haunts her.

“Aaww…” Puzzle said, “… why won’t you sleep here with me tonight.”

“All right!” Cozy quietly said in excitement. Then the two settled in and slept.

Well, that’s my story. I hope you’ve enjoyed it.

And a quick special thanks to AstriaDawn for the Cozy Glow model.