During the usual nightmare Sans finds himself staring at a strange reflection of himself. But something is wrong. When he finally wakes he isn't surprised to find Papyrus in his room, staring down at him. But he is surprised by the changes in his brother since he'd fallen asleep. Who is this evil imposter, and why doesn't his magic work anymore? An Undertale meets Underfell story.

Sans has watched as everything repeated over and over again. So has Frisk. Sans gave up a long time ago. Frisk, she still has plenty of determination. They couldn't end the loop on their own. But maybe, they could end it if they worked together? Female Frisk. Possible future Frisk/Sans.

Auvie has made a promise. A promise that has driven her to travel dimensions in order to fulfill it. However, she's found herself in the wrong dimension. Can she escape, and what will she find while she's there? (Underfell!Sans/Self Insert, sfw but suggestive, trigger warning for mentions of emotional abuse, violence, also sweating and swearing)

Summary: This is Underhell. A human king has taken the throne and rules the Underground with blood. You're a grown woman being thrown into the aftermath and only by making friends with a few monsters will you understand who the real ones are. Tumbler account is amartin22stuff for anyone curious.

One month has passed since Rick B-12 lost his Morty. Called back to the Citadel for reassignment, Rick is stuck with a broken Morty in a bunny suit. Deep secrets lie under the surface, ones that Rick isn't sure about uncovering. After all, this kid is only supposed to be a shield. He can't afford to care this time, but he can't help asking himself... Is this all there is?

When Frisk returns from her first semester of college pregnant, the first person she turns to is her best friend and partner in crime, Sans. But when despite everything, they can't hide their feelings for each other, will the differences between magic and determination push them apart?

[Spoilers For Entire Game] "If we're really friends, you won't come back." After sparing the final boss and facing the consequences for their actions up 'til then, the fallen child takes those words to heart and resets. The next time will be better, but a question still lingers: what does it mean to be "friends"? If they keep going, maybe they'll learn the answer...

You are a human nurse that works at The Hospital of Humans and Monsters, name courtesy of King Asgore. Things are going well for you there, but there's always an influx of monster patients coming in with serious injuries caused by abrasive humans. Things go even further south when you find yourself being stalked by humans literally blocks away from the hospital... Smut later on!

You're just scared of them, you don't hate them. When your mom makes you go spend the rest of the summer with your grandma because you were being too lazy, your phobia intensifies when you're constantly being watched by them. Especially by a short skeleton - which by the way, seemed to scare you most for a reason. / ON HIATUS

The old bookstore wasn't your home anymore, you finally realized. It was with them. It was with him. (Sans/Reader) (cover art by ballroomrittz)

Ebony has been stuck in the Underground for two years now. She struggles to find a way out of there, with hopes of finding what had been lost to her. She just wasn't expecting any... feelings to sprout while Underground, and it begins to interfere greatly with her plans of escaping. (OC/Sans, as well as a little bit of OC/Grillby. May contain smut eventually, but has some fluff!)

Getting more than she bargained for with two skeleton roommates, a blind woman named Dani gives in to her new life of monsters and magic, not imagining things could get any stranger when one of the brothers manages to touch her soul. Dani's new life is both exciting and terrifying; the challenge filling her with determination.

You are an overly flirtatious voluptuous human who fell into the underground to escape from your surface life, but your past threatens to catch up with you when you meet the comical Sans. You desperately try to rebuild and entertain your new life in the underground in the best way you know how... by seducing him. Unlucky for you, he's on to your game. Sans/FemReader

Sometimes it's good, other times it's bad. When everything is gone they reset to destroy in a different way. When everything is won… is great…why do they reset once again? When will they finally open their eyes and QUIT? (I really suck at summaries sometimes. OC fic. Play/watch the game first, there will be spoilers!) Sans/OC with slight Papyrus/OC (Title will prob change.)[Hiatus]

Sans/Reader smut, with one-sided Sans/Papyrus/Reader. Reader is female. You've been without contact with another person for far too long, how will you react when innocent horseplay on movie night threatens to tip you over the edge?

This shouldn't have happened, it was just a hiccup in the timelines. Then again, Frisk should have known things weren't going to so be perfect for such a while. Underfell AU. Obvious spoilers and older fem!Frisk

When a sudden reset wipes catches everyone by surprise, a confused and heartbroken Frisk is brought back to the pile of golden flowers within Mt. Ebott. But something is admist in the Underground. Not only does Flowey not greet them, he also remembers the previous timeline they came from. And red flags start to rise when a confused Toriel stumbles out of the Ruins... W.I.P

Usually when Frisk comes to him at ungodly hours, they are tormented with memories from the past. This time, however, Sans is relieved that this is not the case. Sans/Frisk Friendship.

After being stuck outside of time and space, Frisk finally finds a way back to her friends, but what did she unleash in her escape? An old foe comes back to play and they must defeat it to achieve their happiness. Older Frisk x Sans, Papyrus x Mettaton, Undyne x Alphys, Toriel x Asgore Possible rating change

****SPOILERS ONLY READ IF YOU'VE FINISHED SEASON 2**** Rick Sanchez of Earth Dimension C-137 supposedly ran out on his family 20 years ago, and shows up all of a sudden, and bonds the most with his grandson Morty, taking him on all sorts of adventures through the Universe, along with alternate dimensions... But.. Rick of C-137 didn't really leave his family 20 years ago, did he?

"Stop it!" she cried, "I'm sorry! I don't wanna do this anymore! Don't make me do this!" she begged, "I'm sorry!" After striking down the murderer over and over something different happens. Did her mind finally snap, or has there been something darker and more sinister at play here all along? Rated T for the violence, because Sans is not a happy skeleton when you kill his brother.

Frisk has made her decision. She won't allow the RESETS to continue, with such complications, how can her friends be truly happy? She will make sure they get their happy ending... they deserve it. BEWARE SPOILERS-ONESHOT-MAJOR CHARACTER DEATH.

"Greetings. You have made yourself completely clear. I, your humble servant, will follow you to the utmost..." One-shot. After scores of resets, your last great pleasure is to take up the greatest challenge and conquer him again and again. Oh? You want new content? Understood. If you're bored and you have to drag the others into it to get what you want, whose fault is that, really?

Sans wakes up after yet another reset. However, something is different about this playthrough. Something is loose in the time stream and is wreaking havoc with the way things are meant to be. Older!Frisk helps Sans face his past as they travel between AUs in search of a way home. (Very Head-cannony!) AUs so far: UNDERFELL, UNDERSWAP, BROMALGAMATE.

Sans may not have always been the loving brother we come to meet during Frisk's journey. Once, he might have been openly resentful. But a funny thing happens when you see someone you care for suffer... time... and time... again...

Sans is definitely used to disappointment by now. No matter what pattern begins to develop, he always knows how his life will play out, one way or another. But it becomes harder to predict when an unexpected anomaly gets thrown into the mix, an anomaly that could unravel everything Sans has ever known to be true, and remake it into something tragic...or something wonderful. Sans/OC