Underfalls: The COMPLETE Trilogy To A Gravity Falls/ Undertale Crossover

Adjusting To A New Life- Books 2-3 Filler! Cutscene, for @HansJeffersonZacrias

Okay, okay, I know what I said about finishing the series and not coming back to it. But lemme explain. What I'm NOT doing is writing another book. i feel a trilogy is all that this series needs. But, I can make this exception: I'll do fillers. For example, I got a request on my message board saying that they wanted a filler, or bonus cutscene that would lie in between books 2 and 3 (Breaking the Barrier and Determination Is A Plague). And I figured, sure? Why not? I mean, it's not like they asked me to write 7 more books for them to continue on the series. They just wanted a little more romance here. Because, apparently, making Sans x Mabel (Sable? Mans? Idek e.e) a ship here was good, and everyone loves it. Anyways, sorry for the hold up, and let's get on with the story! (And as you know, this art does not belong to me, credit goes to the rightful owners)

Hope you enjoy!

SansPOV

...

Do you think that even the worst person can change...? That everybody can be a good person, if they just try?

Timelines, usually they just repeat over and over. The same things happen again.

 And again. 

My brother dies. 

I find his remains. 

I seek vengeance. 

Everything goes dark. 

And then. . . 

Its back to the beginning.

But this timeline is... different. Usually, only one human falls into the Underground. Sometimes they're nice, and only kills a few of our kind. Others... I try not to think about. But this time, two humans fell down into our realm. Twins, I think. But you would never believe me that one was a demon, and the other was an angel. 

Yeah, yeah I know. The stupid history books tell you that humans and monsters hated each other. But... Could it be different this time? 

Well, either way, I'm stuck with the timeline I got, I guess. 

"SANS!!!" I blinked open my eyes, my thoughts draining from my head. Papyrus, my little bro, was gazing down at me, a smile spread across his face. "Sup, bro?" I asked casually, happy to see that my sibling was in a good mood. "YOUR HUMAN FRIEND IS SO NICE! AND CLEVER! SO CLEVER THAT SHE PASSED ALL OF I, THE GREAT PAPYRUS' PUZZLES ONCE MORE! BUT..."

I saw Papy's smile drift away, replaced by an uneasy frown. "What? What happened? Do I need to teach someone a lesson-"

"THE HUMAN... SHE... ASKED ME ABOUT THAT DATE I MENTIONED TO HER A WHILE BACK AND... WELL..."

"What?"

"I TOLD HER TO GO SOMEWHERE WITH YOU INSTEAD. IT SEEMS.... WHILE I HAD... DISSAPEARED... YOU TWO HAD BECOME CLOSER... AND... WELL-"

Suddenly, a ball of blue and pink crashed through the door, and tackled my brother. At first, I was shocked, seeing something attacking my brother, but I calmed down immeadiately after I saw the familar face of Mabel, one of the two humans I had mentioned earlier. "Hey guys!" She shouted as Papyrus hugged her tightly. "WELCOME HOME, HUMAN! WE WERE JUST TALKING ABOUT YOU, ISN'T THAT JUST THE COINCEDENCE?!" Mabel looked over at me for a few moments, before turning back to my brother. "'Bout what?"