So, possibly the first Multi-chapter I'm doing and posting (Besides the Story version of Renee's comic). This story was inspired by the video Anti Gravity {Undertale} by KittyKana13 on YouTube. If you have not already, please go and watch it, it is amazing, and it's done amazingly well. This story will be taking place AFTER the True Pacifist ending.

Warning- Violence and gore and overall dark shit, will be in this story.

Full Summary- Sans had known that it wouldn't last long. He knew that eventually something would come to destroy the happy ending that they all had. But now, he couldn't get himself to accept it. Right now, he found himself wanting to believe it as a nightmare, wanting to wake up. He felt his brother's hand on his shoulder.

"…You must stop it. All of you, monsters and humans must fight together in this war."

It has been several years since the barrier has broken. Frisk and Sans were happy, as well as their family. There were still tension between the humans and monsters, most humans still hated the monsters and wanted them gone. But an old enemy arises, seeking revenge and this time, they have an army behind them, Sans and Frisk realize that they have a war looming over them. Warnings from an old friend and Flowey tell them the only way to beat the threat is to have the humans and Monsters work as one. Doesn't help that to warn their family and friends, they'll have to tell the one secret neither of them want to tell.

Notes- Frisk is going to be non-gendered. If I slip up at any point and say 'him' or 'he' when referring to Frisk, I am sorry.

Frisk is going to be about 19-20 years old in this.

This does have Sans / Frisk, Toriel/Asgore, Undyne/Alphys, and Papyrus/Mettaton. Those are the pairing.

There are a few O.C's. which will be added to my profile as in here for when they appear. These OCs are NOT in any way too be taken as main characters rather just the humans that are friends with Frisk and Sans and the others.

Gaster is a Skelebro in my stories. I like to think that he is a Skelebro.

That's all you need to know so far. So… Without further delay, please enjoy the Prologue of Anti Gravity.

Undertale © Toby Fox

Story © me

Song © roundabout

~*~*~Anti Gravity~*~*~

~*~Prologue~*~

Sans dodged another attack and seized a bone and wacked the thing in front of him away. It screeched as the bone shot up impaling it more shot done from above crushing it went limp and turned to smoke. The skeleton glanced around he saw Papyrus and Undyne fighting back to back, he relaxed seeing his twin still alive and looking well. His eyes shot around as he let his magic protect him and kill off the creatures trying to attack him. Everyone seemed to be all right but he didn't see Frisk. He looked around frowning with worry, as he throw a creature to the side into a group of them and crushed them with his bones.

"Where's Frisk?" he asked as he jumped towards them to avoid an attack. His brother killed the creature as it lunged again and he nodded his thanks.

"Frisk is missing?" Undyne asked.

"If they weren't I wouldn't be-" Sans was cut off by a shriek. The three froze and looked towards where it came from just to see Toriel burst to dust followed by Asgore. They didn't have time to mourn as they were suddenly surrounded and fighting, Undyne cried out throwing herself at the creatures. Sans called out to her as he dodged an attack and took out another creature. He moved to help her but got there too late and ended up getting covered in dust. He stepped back then spun teleporting the short distance to Papyrus' side. They fought for a while but both were wearing down and running out of food to heal. Sans summoned the GasterBlasters and took out about fifty of the creatures. They shrieked as they turned to smoke. He heard Papyrus yelp and turned his head to see his brother kneeling.

"Papyrus! NO!" he yelled he sent an attack at the creature taking it out and ran to his brother but couldn't kill the next creature that got to him first as another tackled him he blasted it and rolled turning to his brother just as Papyrus turned to dust.

"NO!" he screamed. He got to his feet, and sent an attack at the cackling thing. It shrieked and tried to flee but Sans seized it holding it in place as it was buried in bones. He looked around, he saw Frisk come flying out through the crowd of creatures, humans, and monsters. He caught them with his magic pulling them to him. He released the magic catching Frisk and holding them to his chest. They groaned looking pretty beat up but alive. The human looked up as him.

"S-sans…: they whimpered.

"Frisk… No… Please hold in there. Please… I can't lose you too." He said glancing at their soul. It had cracks running through it. He reached into his pocket but found nothing. He was out of food. Frisk shuddered

"…I'm sorry… Sans… I… I love you…" they said. Their soul shattered and Frisk went imp in his arms.

"Frisk… Frisk... No… No… No… No! Please! Please do-don't leave!" he cried. He closed his eyes holding his lover's body close. Suddenly the weight in his arms vanished, and the sound of fighting went silent. His eyes opened he was in… the lab? He stood slowly looking around. What the hell?

{Sorry, I didn't want to hurt you but it was all I could do…}

Sans looked towards the voice, "…G-Gaster?" he voice broke as he saw the older skeleton. A crack ran up from his right eye as one ran down from his left.

{Sans, there's a war coming. And you and your friends must be prepared for it.} the scientist said. Sans frowned.

"…That… That was… " he mumbled.

{A vision, of what will happen if precautions aren't taken.} Gaster told him. Sans stared at him.

He closed his eyes, "No… No, this can't happen. We're finally happy.." He said. Sans had known that it wouldn't last long. He knew that eventually something would come to destroy the happy ending that they all had. But now, he couldn't get himself to accept it. Right now, he found himself wanting to believe it as a nightmare, wanting to wake up. He felt his brother's hand on his shoulder.

{…You must stop it. All of you, monsters and humans must fight together in this war.} Gaster told him.

"…How? Half the humans still hate us… How are you even telling me this?" Sans asked.

{I'm sure you'll find away. As for how I'm able to talk to you, I'm assuming it's got to do with the machine. But that isn't important, Sans. What is important is stopping this war or preparing to fight it.} the elder skeleton said.

"…I'll… I'll try… Gaster…?"

{I'm not sure Sans. I'm wondering it myself… I need to go… My magic is failing me… Remember, Sans, the world is depending on you and your friends….. save it!} he was fading. Sans jumped and reached out to grab him

"Brother! Wait!" his hand closed around nothing but air. "… don't leave…" he whispered.

The world went black.

Sans woke, and sat up looking around frantically. He blinked, seeing he was in his room. He looked around slowly, everything was the same as his room had been in Snowdin. The self sustaining trash tornado spun in the corning his computer and desk sat on the other side of the room, a soft hum coming from the computer. His treadmill was still in the middle of the room. He looked down beside him. Frisk had their back to him, still asleep. He sighed and rubbed his face. It was just a dream, but it had felt real. Sans cursed quietly and closed his eyes. He laid down wrapping his arms around Frisk and pulling them close burying his face in the crook of their neck. He relaxed, as he matched his breathing with Frisk's,

The human shifted pressing back into his chest, their hands coming up to grip his. Sans smiled a little, before he drifting off.

Frisk stayed quiet and relaxed, their breathing easy as they pressed back in to Sans and gently gripped his hands. They felt Sans smile before he fell back asleep. They had woken up before the skeleton, they had dreamed of a warning Flowey had given them. A warning that had shaken Frisk.

A war was coming, and Chara was leading the rival army.

The human sighed and closed their eyes. As they fell asleep, they wandered if Sans had gotten a warning as well.

~*~*~Anti Gravity~*~*~

~*~Prologue End~*~

I'll see you all in the next chapter. Until then keep reading and Writing. Love you all.

~Shadow On The Full Moon