In the king, Queen, and Knight fight you fight right next to the dark fountain but after the king and queen fight you go up and to the right and your directly in front of it. This makes no complete sense, tricky toby whyyyy!!!! 
I think we already have a thread that talks about this?
Where?
So uh hey this is my headcanon
This makes sense especially because after going to the castle once and exiting the card castle via the gate you end up where lancer joined the party instead of the path to the castle
yeah
i also always wondered if the black space is just "don't step on dirt" or just a Void and Lancer and other guys just float
Technically, this also happens after all of the major fights in the game actually.
After the knight you run to the right and up in the grand door.
After the titan you constantly go up and to the right. You also do so after comforting Ralsei in front of the final tragedy panel.
After Flowery you go to the right and up to seal the first fountain and again after he dies.
What is it with Toby and constantly going to the right and up to seal the fountain?
I didn't include cause' I didn't remember but tricky toby doesn't like physics
going rightwards is common video game direction, and upwards is how Toby thinks it's easiest to represent the fountain.