Luna flew through the land between dreams and reality, looking for anypony in distress or any wishes she may be able to grant. One dream drifts away from the others, she inspects it and finds that it is a dream from another world. Dreams do tend to wander into other worlds and Luna always enjoyed looking at the dreams from beyond Equestria. She flew inside the dream and found a field with some of those...What were they? Humans? Yeah those, she found some of those things lying down in a grassy field together.
"Seems a bit boring... I wonder what's really going on here?"

She flew in closer to the humans and noticed they were all wearing some kind of matching uniform and a pile of strange equipment lay in a pile next to them.
"Did we really do it Captain?"
"Yes Eren, we finally rid this world of the Titans."

What in the name of Equestria is a Titan? Luna thought to herself. She soon realized that this was a dream and that this is most likely what the dreamer wants to happen.
"I'm sure we can investigate this further... Perhaps we could assist them? There's plenty of room in Equestria after all!"

Luna was excited at the thought of helping those of another dimension, she used a spell that saved a dimension's 'code' so it may be used another time. This was the way she had enchanted that mirror to enter Canterlot High all those years ago.

Eren tried to open his eyes, was he outside? No! Was he outside the Walls? Titans could appear at any moment! He needed to-
"Ah, your're finally awake!" A feminine voice chimed
"T-titans... We need to-" Eren let out a yawn
"Run...."
"Now why ever would you need to do that darling?" Another feminine voice (that for some reason reminded him of Captain Levi...) asked him.
"W-what's a Titan? It sounds scary..." Yet another female voice asked whoever else was there while sounding absolutely terrified.

Eren began to realize how odd he felt, his hands and feet felt numb and his whole body felt warmer than it should have been... He tried to stand but found he could not balance and fell on his face. He finally opened his eyes and saw a group of...

COLORFUL HORSES??

"OH GOD WHY AM I SURROUNDED BY COLORFUL HORSES AND PEGASI AND UNICORNS OH GOOOOOOOOD!"
"Um... Eren... You-" A white Unicorn with a golden mane and tail spoke to him with Armin's voice.
"ARMIN?"
"Yeah... Me... You're a Pegasus too..."

Eren's eye twitched.

"Eren?" Armin gave a concerned look.

"WHOEVER DID THIS WILL FEEL MY FIERY WRATH!"

A few hours later...

"So I have been transported to another world by an Alicorn Princess Pony because she saw my dream of a world with no Titans?"
"Yes." A lavender Unicorn had just explained to him, Armin, Mikasa, Jean, Sasha, Christa, Squad Leader Hanji and Captain Levi. Why they had suddenly changed species.
"It will take some time for Celestia to enchant another mirror portal for you to return home so I hope you enjoy your time in Ponyville!"

Author's Note

This is something that I will update while Fallen Star is being proofread or I don't have quite enough time for a new chapter. It will basically be short stories about a day in the life of one of the AoT characters and the shenanigans they get up too, I'm all up for suggestions as for what those shenanigans could be so comment away! Hope fans of Mlp and Attack on Titan/Shingeki no Kyojin enjoy!