You walk onto a set. Houses were painted behind a red prop of a tower with a vine. You cautiously approached, when a familiar robot peeked out from behind the set piece.
"Oh? That human… Could it be? …My one true LOVE?"
You shivered at the capitalization of love, even though you didn't (yet) understand what that meant.
Wearing a light blue dress that brought out all the red stains, Mettaton walked down the stairs of the set.
Mettaton began to sing something about you being his one true LOVE who was kept away from him because the king didn't like humans. You wondered why anyone would watch ANYTHING like this. It was just a robot singing terribly with blood-stained petals floating nearby. Then again, were you getting so used to everything being red that you didn't even react anymore? If you got back up to the surface, would you ever be the same?
You tried ignoring Mettaton and the thoughts in your mind in favor of trying to find a way out of the set. Unfortunately, every time you tried to leave the stage, you would get electrocuted by a blue laser.
"Blue attacks only hurt you if your moving," Flowey said, "So the laser is impassable. Looks like you'll just have to wait."
Mettaton, meanwhile, was wrapping up his song. "So sad it's happening. So sad. So sad that you are going to the dungeon. Well, toodles!"
And with that you fell through the floor. A trapdoor? Really, how original.
"Oh no. Whatever shall I do? My LOVE," Mettaton once again said capitalized, "has been cast away into the dungeon. A dungeon with a puzzle so dastardly, my paramour will surely perish. O, heavens have mercy. The horrible colored tile maze. Each colored tile has its own sadistic function. For example, a green tile sounds a noise, and then you must fight a monster. Red tiles will… Actually, wait a second. Your smart. I'm sure you can figure it out, darling." Mettaton cackled evilly. "Oh, and if you can't get through in 30 seconds…"
A firewall appeared behind you.
"You'll be incinerated by these jets of fire! Ahahahahahaha. Ahaha… ha… ha. My poor LOVE. I'm so filled with grief, I can't stop laughing. Good luck, darling."
After a bit of trial and error, you managed to figure out what all the tiles did. You were covered in piranha bites from before you realized they liked the smell of the orange tiles and your hair was frizzy from going through yellow tiles and blue tiles next to yellow tiles. Still, you raced through the puzzle, not stopped by anything, as Mettaton's singing grew less and less confident. However, once you finished the puzzle, you heard Mettaton…
Laughing.
"Congratulations. You made it through the puzzle! And now, without further ado, the flames will be deactivated. No. More. Fire. … But it's as the phrase goes. "Out of the fire, and into the frying pan." That's right, darling. Even if you manage to beat the heat… You'll never be able to withstand my hot metal body. Prepare yourself to be defeated!"
"Wait wait wait," Flowey said. "Why would your viewers want to watch you beat Frisk? After all, the hero should always plays by the rules. And the rules say we should be able to leave the dungeon because we beat you. That was the deal. The puzzle's over."
"Puzzle? Over? Little flower, darling, what are you talking about…? Did you forget what the green tiles do? They make a sound, then you have to fight a monster. Well, darling… That monster… is me!"
And then another battle sequence started.