I wrote this in the span of two days or so, but... whatever. My first Undertale fic, and I figured I'd make it as humorous as possible.
Basically I came up with the idea by thinking of how a normal person would react to an unbeatable puzzle being beaten, like what can happen in the fourth Mettaton encounter. Seriously, I think Alphys thought it was impossible without studying the rules and floor layout, so the human just waltzing through it would be hilarious.
The rest of the encounters got tossed in there because I don't see any reason not to.
Off The Rails
"Who does Dr. Alphys have a crush on?" Mettaton asked the human.
"Why, that's obvious, it's me!" The human replied, mostly sarcastic, just to see the reaction.
They were met with silence. Even the music that had been playing in the background fell silent.
"Wow," Mettaton finally said.
"You've got to be kidding me," Alphys muttered, so shocked by the answer that she forgot her usual stutter, turning to glare at the child.
"Nope!" The kid said happily.
"My, how conceited of you, darling. I love it! Just for that, I won't put a penalty on that!"
"You've got to be kidding me," Alphys repeated.
Meanwhile, the human simply laughed.
Mettaton approached the seemingly uncaring child with the chainsaw. How exactly that was going to remove the soul since it would only be harming the physical body was beyond anyone's knowledge. Of course, they didn't particularly care anyway.
The human's phone rang. Mettaton paused, the chainsaw still making an awful racket, and swiped the phone from their pocket, answering for them, yelling above the noise, "What is it? We're kinda in the middle of something!"
"W-wait a second here!" Alphys said, wondering if she was actually being heard over the noise in the background. "Can't you just use a substitute?"
"Why?" Mettaton asked, still shouting.
"W-what if someone's a… vegan?"
"Vegan," Mettaton replied, deadpan. "Milk and eggs aren't vegan options either. I'm halfway into this; I'm not going to stop now."
"Fine, vegetarian," Alphys snapped, for once being quick to reply and having something that would actually make a lot of sense ready.
"Vegetarian…?" Mettaton asked. A moment later, he turned off his chainsaw. "Guess I can't argue with that one. Well, that's one creative scheme to murder this poor child out the window. Nice job," he muttered sarcastically, shoving the phone back into the child's hands before running away.
"Geez, thought he'd actually try to slice you up there," Alphys muttered, letting out a small relieved sigh.
"You need to fix him," the human commented offhandedly.
There were bombs literally running around the place. Mettaton fully expected to enjoy watching the human run around like a chicken with its head cut off. To his surprise and annoyance, however, the kid actually yawned and sat down, staring into the darkness of the abyss under the platforms of rock.
"Hey hey hey, what around you doing, darling?" Mettaton asked, flying back into the area.
The human looked at them lazily. "If those bombs were real, wouldn't you be running for your life right now? I don't care if your metal shell is impenetrable, you'd still get pretty dinged up, and I have a feeling you're the type to freak out over the tiniest scratch. You'd probably blow up half of Hotland, too, and I doubt that anyone wants that."
Mettaton was silent. "God dam…" He silenced himself. Yes, he was supposed to act like he'd gone haywire, but that didn't mean he could swear on TV. "Alright, you got me," he muttered, flying away in annoyance.
The human's phone rang.
"H-hey, wow, you knew they were fakes? How?"
"I don't think a dog-shaped bomb would really work. I have seen some strange things down here, though… It didn't seem possible."
"S-so you were just calling his bluff?"
"Yep."
"Well, that's gutsy. W-what would you have done if they were real?"
"I trust you," the human replied. When Alphys didn't reply, they said, "I'll be continuing, then," and hung up.
"The human finished the puzzle," Mettaton informed Alphys, who had just popped into the conversation via the human's phone.
"T-that puzzle?" She asked, incredulous, not quite processing this information correctly for a couple moments. "B-b-but I designed that thing to be impossible! Er," she halted, glancing at the human's impassive face on her screen. "I-I mean, I'm glad you beat it, don't get me wrong. It's just that you shouldn't have." She sighed, and then proceeded to grumble to herself. "Man, this means I'll have to redesign it. After all, that was on TV, can't have the answer already known to challengers. Course, who bothers trying?"
After a moment of listening to the lizard monster's mutterings, Mettaton let out sound that sounded like he was clearing his throat, completely disregarding the fact that he lacked one.
Alphys paused. "O-oh, sorry."
"You're an odd one," Mettaton commented.
"H-hey," Alphys muttered, offended.
Mettaton chose to ignore that, and returned his attention to the human, clapping his hands together and shedding his ridiculous dress. "Now, let's go kill some people," he said ominously, and yet with a surprising amount of cheer, as though he were going out for the day with some good friends that he hadn't seen in a while.
And thus, the fight commenced.
