Hey everybody. So, I just got to the Sans fight in the Genocide route (though I doubt I'll complete it. I don't think I have it in me to kill Sans). This story came to me one day, about what would happen if Sans met Genocide Sans. Hence this story. Hopefully you guys all enjoy.

"Please...I'm sorry. I didn't want to!" Sans looked down, feeling nothing but anger towards the boy knelt before him. He was coughing and hiccuping, his crying having got the better of him. The little boy looked up at him, one hand over his chest. His soul floated before him, the red color a stark contrast to the darkened room. The boy looked up, eyes sliding open for the first time since he'd known them. Dark eyes slowly faded to red, the sad expression turning more twisted. "This was your one chance to save him," the boy taunted, voice distorted.

"I know," he said, raising a hand. The bones that followed his command hovered behind him, all pointing towards the boy. The boy frowned.

"What?" he asked, "you'd kill this child?" Sans chuckled.

"I told you before didn't I?" he said, "That you'd have a bad time. Now goodbye...Frisk..."

Sans' eyes snapped open, left eye glowing with energy. He sat up, taking a deep breath to steady himself. 'That dream again,' he thought. He shook his head, looking around. 'I must have fallen asleep on the couch again.' He stood, calming down the energy flaming around him and heading for the stairs. 'Better check on the kids. Toriel would be livid if something happened to them.' He pushed open the door to his brother's room, peering inside. Papyrus was lying in the center of the bed, arms wrapped around the children on either side of him. Frisk was lying on his back, sprawled out with limbs everywhere. Asriel was curled into Papyrus' side, and Sans smiled recalling how one of the human souls had stayed behind to give the little monster another chance. He chuckled, turning and leaving.

Halfway down the stairs he paused, energy flaring to life again. Another scene passed before his eyes. Frisk kneeling on the ground, staring up at him.

"You plan on coming back again...don't you. Fine. But I'll be here to knock you down again kid. Remember that." Frisk's smile, even as blood pooled around him.

"I don-*cough*...don't plan on coming back. Just...Sans...I-I never-*cough cough*...wanted to hurt him. Never...Papyrus..."

The vision faded, leaving the skeleton slightly dizzy. 'Papyrus?' he thought, 'Why would I have a thought like that? Of Frisk...killing Papyrus.' He shook his head, feeling his energy settle down. He started down the stairs again, planning to head for the couch again and get some more sleep.

"Sans?" he stopped, looking back. Frisk stood halfway up the stairs, watching him with tired eyes. "Is something wrong?" The skeleton shook his head, smiling.

"Everything is fine kid," he said, "so you should go back to sleep." He turned away, only to feel a hand grip his. He looked back, seeing Frisk. Now that they kids had grown a bit, each around the age of ten or so, Sans no longer stood above them. He'd grown a bit himself, but now was only an inch or so taller than the other. Frisk looked at him, silent. Sans sighed. "Fine kid. but just for tonight." Frisk giggled, flashing a smile.

"Okay Sans," Frisk said. The skeleton chuckled and laid down again, allowing the boy to curl up beside him. He shut his eyes, falling back into sleep.

'Well well...so peaceful he is. Too bad it's going to be his last day. Goodbye human child. It's time to meet your fate.' He readied his attack, eye flashing.

Sans snapped awake, raising a wall of bones on instinct. Frisk woke as another attack slammed against it, loud cracking noises sounding. "S-Sans?" Frisk said, "What's happening?"

"Don't worry kid," Sans said, "go upstairs and wake Pap." He created a safe path for the human to run, footsteps echoing up the stairs. Sans let his wall fade, finally getting a look at their attacker. What he saw surprised him.

"Ready to have a bad time?" the other asked with a grin. Sans glared, energy flaring to life more than ever before. He could hear Papyrus coming downstairs, calling out to him.

"SANS?" Papyrus asked, "WHY ARE THERE TWO OF YOU?" Sans ignored him, eyeing the copy of himself standing a few feet away. His signature jacket was white, and Papyrus' scarf was wrapped around the copy's neck. A long, bloodied slash ran from the double's right shoulder to his left hip. At the place where Sans' eye normally glowed blue, the double's eye glowed red.

"Who are you?" Sans demanded. The double shifted, cocking his head.

"I'm you," the double said, "from another timeline. A timeline where he-" The double pointed towards Frisk, "ruined everything."

"Frisk could never hurt anyone!" Asriel yelled. The double shot Asriel a glare, raising a hand. Asriel's soul blinked into existence before him, suddenly turning dark blue. The double lifted him up, ignoring his shocked cry.

"In this timeline...you might see him as innocent. A pacifist. But in my timeline...he became a killer. I come from a timeline when your friend committed a complete genocide. Every monster. Dead." He tossed Asriel aside, giving a viscous grin as he looked back at Sans. "You're me from this timeline. Surely you've seen that potential. That...with one wrong move...this human...could become a killer."

"SANS!" Papyrus said, "WHAT IS THIS CLONE TALKING ABOUT?" Sans stayed silent, watching his double closely. He felt someone grab his sleeve, looking down to see Frisk half hiding behind him.

"This child hasn't done anything wrong," Sans said, "I dunno what the human in your timeline did, but Frisk here couldn't hurt anyone." The double laughed, left eye flaring while his right eye went dark.

"You wanna know what he's done. What he has the potential to do? In your timeline, you still have your friends. You still have your brother. In my timeline..." He closed his eyes, and when they opened again they were nothing but black holes. "everybody is dead..." Sans frowned, energy blazing around him as the double did the same. "Normally...I'd kill you for standing in my way. However, killing myself doesn't seem like a good way to go. Besides, killing another me in another timeline? There's no telling what would happen then." The other skeleton chuckled. "Welp. I'll be seeing you. Just a warning though kid. If I see you, then you're a dead human."

"F-Frisk!" Asriel said, going over to cling to the human, "What's going on?"

"Sans?" Frisk asked. The skeleton sighed.

"Don't worry kid," he said, "Everything's gonna be fine."

"THAT'S RIGHT. SANS WILL FIGURE IT OUT. HE'S JUST THAT COOL!" Yet for once, despite his brother's confidence, the skeleton wasn't entirely sure he believed his own words.

So, lemme explain my design for Sans. He's one of those people who I feel like is extremely powerful, but he can't beat everything (As evident by how the player can beat him in the Genocide Run and Flowey can overpower him in the Pacifist Run). I figure he knows what battles he can and can't handle, and with Genocide Sans having nothing to lose he's got the advantage.

Anyway, thanks for reading. Please leave a comment. It'll help a lot to develop the story and my writing as a whole. See ya next time.