Okay, so this is based off what I and my rp partner had done with our HoneyMustard rp. The Title says it all really lol. Also I'm not good at one shots…nor do I like one shots to be perfectly honest. But uh…I'll make an acception. Also, I do call Fell Sans Red regardless of whether Swap Sans is around or not. Easier to differentiate…

Disclaimer: I do not own Undertale, Underfell Sans and Underswap Papyrus belong to their respective creators.

Echoes of Sin

Papyrus panted as he pulled out of Red and laid beside him in the mess of echo flowers, humming softly; both skeletons panted a bit as they laid there. Their ecto-magics started to dissipate from their groins and Red chuckled a little as he sat up. "That…was so fuckin amazing." He said and stretched a bit. The two skeletons had been at it for a couple hours and had been pretty vocal though out the whole thing. Especially with their souls having been tangled in their own little love making, still dripping from where they were floating.

Red and orange ecto-juice leaked from both souls, which weren't quite ready to separate just yet. A small chuckle escaped Papyrus. "Yell yeah…" He replied, pulling out a cigarette and lighting it before sitting up himself, though the two weren't ready to get their clothes on just yet.

A gust of wind blew throughout the underground, making both skeleton's shiver only slightly and Red froze. The wind had brushed against the echo flowers…their love making and calling each other's names from earlier playing loudly. God, it was like an audible porno or something…it was just beautiful yet very frightening all at the same time.

"Oh shit…this is fucking awesome." Red laughed.

Papyrus chuckled slightly and took a puff of his cigarette. "But…you realize; we're going to have to change every single flower that our voices reached right?" He asked, glancing at his lover who gave a small groan. "You gotta be kidding me Stretch…"

"Fraid not…" Papyrus replied and looked around. "What if a kid or some other monster walked in here and touched the flowers?" He asked.

A hum escaped Red and he thought about it for a moment. "Alright, I got an idea." He said, getting his clothes on.

"What?" Papyrus asked as he got his own clothes on, cigarette resting between his teeth as he looked at his lover, placing both his hands in his pockets.

"How 'bout a joke?" Red asked, looking up at him; his own hands going into his own coat.

Papyrus shrugged and smirked a bit. "Alright, what did you have in mind?" He asked and watched as Red took a big breath of air before yelling at the top of his lungs.

"KNOCK KNOCK!" He screamed and looked at Papyrus who just chuckled softly.

"WHO'S THERE?" Papyrus yelled just as loudly after taking his cigarette out of his mouth.

"WILL YOU…" Red fired back.

"WILL YOU, WHO?" Papyrus asked.

"WILL YOU MARRY ME?" Red yelled and then the both of them laughed as they walked off, Papyrus grabbing one flower their voices didn't seem to reach. It was still going off with their screams and moans. "You realize…some poor sap is gonna walk in there with his girlfriend, and he's so gonna have a heart attack." Papyrus said, chuckling.

"Ah well, that'll be fun to see though." Red smirked.

I'll admit, I'm kinda not happy with the length…though that's just me having issues with a chapter not reaching 1000 words. Oh well, I hope you enjoy it. My first Honey Mustard fic.