I don't really know. I'm sorry.
After many fights, both against titans and humans, loss of friends and... limbs, Eren and his friends finally made it outside of wall Maria.
It was beautiful.
But just seeing the new territories, untouched by human foot for over a century, wasn't enough. They had to see the ocean, and with Eren's amazing ability, that was absolutely possible.
However, the further away from wall Maria that they went, the deeper into plain land they seemed to go.
Even on top of Bertholdt's 50-metre titan form from the tallest hill they couldn't see the so-desired blue destination.
Yes, even Historia standing on Ymir's titan sitting on Eren's titan shoulders sitting on Bertholdt's titan shoulders standing on the tallest hill couldn't see it.
They were just about to give up on their quest for the ocean when Historia noticed something quite different.
She couldn't quite name it, but it seemed important, and they had already wasted enough time, so they could continue.
In a few days they arrived at what seemed to be... a wall?
It was not like any of the walls they had ever seen before, as it was completely white, and seemed to go on endlessly into the sky and around the world.
They called it the Fourth wall.
So obviously the most logical thing was to have Berthold and Reiner break a hole in it like they did with wall Maria.
And with great efforts from everyone, they made a hole big enough for everyone to pass through.(Well, maybe without the horses.)
Inside the hole they found a long dark tunnel... with a light at its end.
Everyone from the quest to the ocean found themselves in a completely unfamiliar environment.
There were so many strange things that everyone besides Hanji were just standing there dumbfounded, astounded, flabbergasted and about a hundred more synonyms for amazed.
Meanwhile, Hanji was in heaven, jumping from one strange thing to the other.
Their little scene was interrupted when some people entered the room the Shingekis were in.
The new people were dressed very strangely, used even stranger words and some of them had the same voices as the Shingekis.
The last man to enter the room dropped his coffee. The creator of Attack on Titan himself went pale.
How could his creations be here? He knew they shouldn't have taken such a long lunch break.
The creator's worst, most irrational fear had come true: his characters had come to get their revenge for all he had put them through. He couldn't have that happening, so he turned around and ran, ran, ran as fast as his feet could take him.
He went so fast that he went back in time and found himself, right before he would publish the pilot of his manga, and stopped himself from ever doing it.
Attack on Titan never existed, but because they had already left their own universe, the Shingekis managed to adapt to this new and much safer world, never even looking for their creator despite his fears.
Based on a prompt on tumblr, which I can't find for some reason.