Story of a Murderer

## Act 1

As Sans woke up, he looked at his hand immediately and saw black veins extending to his hand from his arms.

"It worked !" he shouted.

"Finally, I can make permanent changes to the timeline," he said to himself. Then, as he was getting up from his bed, a black dagger formed in his hand from a black liquid. He made his way into the hallway and saw Papyrus cleaning. He threw the dagger at Papyrus. As the dagger beheaded Papyrus, his head fell to the ground, and his body collapsed.

"Sorry, bro," Sans said without any emotion whatsoever. He went downstairs, took a butcher knife from the kitchen, and then put it into his jacket. After that, he teleported to the ruins. At the very beginning, he began to walk around, each step echoing through the ruins. He made his way into a dark room with a single circle of grass in the center. Then, suddenly, a flower said :

"Howdy! I am Flowey," but before Flowey could even realize it was Sans, he grabbed Flowey, pulled him out of the ground, and slowly squeezed him. Sans smiled the entire time, savoring the cries of pain that Flowey made, eventually killing him in the process. Making his way into the ruins, Sans then stretched with a sudden movement. The ground cracked, and a shockwave shook the surrounding area. He slashed and killed monsters throughout the ruins with a black blade in his hand. As he cut the monsters into pieces, his LV increased. Suddenly, fire rose from the ground, knocking him down. But Sans smiled like a psychopath, as he usually does.

"Y-You monster," Toriel said, fear evident in her voice, and summoned fire columns surrounding Sans. Sans quickly used the black liquid to create another blade and blitzed at her, slashing her in an X shape and damaging the walls with the slash. After that, Sans continued his rampage in the ruins, eventually reaching the gate. He went through it and made his way into the snowy terrain. There was no one, as no one ventured in this direction of the ruins. Sans slowly walked through the area, heading to Snowdin. He pulled his hood up and continued walking. Despite the puzzles his brother made, he ignored them and proceeded to Snowdin.

It was full of life, with monsters chatting and entering shops to buy things. People were gathered in front of the house of Sans and Papyrus, some looking at the window, some entering, and several royal guards, including Undyne herself. He walked there, acting like nothing had happened ; royal guards were preventing people from entering the house.

"What... happened here—" Sans asks with a fake yet confused tone, though it wasn't noticeable. Undyne came from the house.

"I think you should see it yourself, Sans," Undyne said as she stepped aside to let Sans enter. As Sans entered, he saw the dust left behind by Papyrus's corpse. He fell to his knees, some tears running down his face. They were fake, though, like his voice previously ; it wasn't noticeable. Then, black chains formed from a black liquid and impaled him, or it looked like they impaled him. Undyne backed away, getting into a defensive stance, which the other royal guards also did. Civilians started running as many black knives, daggers, and spikes flew in every direction, killing them one by one, shredding and puncturing their bodies. Black stakes rose from the ground, impaling the royal guards. Undyne got impaled by chains and stakes at the same time. After making sure everyone was dead, Sans got up from the ground, walked outside as if nothing had happened, and made his way into the waterfalls. There weren't many monsters ; there were only some flowers, though he ignored them and continued his way.

He arrived at the Hotlands. He slaughtered every monster he saw, killing them one by one. However, when he was about to enter Alphy's Lab, the door exploded, throwing him backward into a wall. Sans got up and looked at the smoke caused by the explosion ; a humanoid figure was emerging from it. The figure stepped out of the smoke; it was Mettaton in his NEO state. Mettaton pointed his blaster at Sans and said :

"I was first made to eradicate humans ; however, it seems I will first kill a monster instead," Mettaton said in a cold voice and fired a laser at Sans, who dodged and appeared right beside him.

"Wow, that's a cool toy, let me play with it!" Sans said in a sarcastic tone as he slashed the blaster in half with a black blade, then stabbed Mettaton in the chest. Mettaton vomited machine oil as Sans continued to stab and slash him, dismembering him finally. Sans then entered the laboratory.

"Come out, we both know you will die anyway," Sans said while he was walking around the laboratory. He found a locked door and slashed it in two. There was a staircase. He made his way down, his steps echoing. When he finally arrived, he saw there was a bigger laboratory underneath.

"How boring... I bet she will try to use that Soul Extractor. Too bad, I know how it works!" He said to himself as he progressed through the True Lab, finally making his way into the Soul Extractor room. As he stepped in, blast doors blocked the exit and entry.

"How predictable," Sans said to himself as the Soul Extractor started to charge. He snapped his fingers and black chains appeared and cut through the Soul Extractor.

"G. didn't make this thing that durable, did he ?" Sans said with a bored tone, then summoned a Gaster Blaster and fired it at the blast door, obliging it. Alphys was watching from the CCTV.

"W-what... how did he do that? Those doors were supposed to be capable of resisting 2 tons of TNT," she thought to herself. But before she could do something else, a sort of black dagger cut her head in half at high speeds, killing her. After that, he left the laboratory.

"What a waste of time," he said to himself, getting bored due to a lack of challenge.

"It was a lot harder and more challenging when I first started this thing," he said as he slowly walked to the last corridor, not expecting any action until he made it into the throne room. However, as he arrived, he saw a big figure holding a trident in his hand. It was Asgore.

"I wasn't expecting you here—" Before Sans could finish, Asgore lunged at him, swinging and thrusting his trident. Sans teleported out of the way.

"So you are aware of what I did," Sans said to Asgore as Asgore started throwing countless fireballs at Sans, who dodged them one by one. Sans then began firing black daggers, knives, and spikes in every direction at supersonic speeds. They cut Asgore, but it seemed he didn't care as he stabbed the ground, creating a big red explosion and sending Sans flying toward the city below. Sans got up ; the explosion caused some cracks in his bones. He looked up as Asgore jumped at him from above and quickly dodged. Asgore landed on the ground, creating a shockwave, then started to change the shape of the trident as if it were something flexible. He shaped his trident into a sword, a green sword that combined both orange and blue attacks, a sword that could immobilize the target and inflict serious damage. Sans just watched as he got ready to fight seriously.

Asgore started to send green slashes, but Sans dodged them and summoned a Gaster Blaster under him, using it to fly. He then summoned three Gaster Blasters pointed at the ground. As he snapped his fingers, all the Blasters fired black rays of energy, causing an explosion that destroyed every single building in a five-hundred-meter radius. As Sans thought he had won, fire pillars rose, burning the Blaster he was on, as walls of fire surrounded him. Then, a red trident suddenly hit him, combusting his body. He fell from the Blaster to the ground. Sans's jacket and shirt were burned ; there were multiple cracks over his body and a big hole in his head. Sans then suddenly remembered something :

"I was able to copy the abilities of others that I killed with my attacks. With my new power, I can perfectly copy the other abilities !" Sans thought to himself as Asgore approached him. Sans got up and posed as if he was about to throw a spear and then a black spear formed in his hand, a black spear made of pure energy, and threw it at Asgore who wasn't able to react to it and flinched due to it. Sans then started to use the black liquid again as knives and spikes came from every direction at supersonic speeds. Asgore effortlessly parried and blocked them with his trident, then reflected them at Sans who also dodged the reflected knives then snapped his fingers as many black spears appeared in the air and all of them flew at Asgore at speeds near hypervelocity. Asgore tried to block them but he was too slow and got overwhelmed due to the high speeds of the spears. He was getting seriously injured. Then, black chains shred his armor, skin, and body, finally killing him.

"That was intense," Sans said to himself, panting even though he was a skeleton. Sans used the black liquid to create new clothes for himself. After doing this, he teleported to the destroyed Last Corridor.

"What a mess," Sans said, a bit annoyed, as at this point he saw the Last Corridor as a home after so many resets and timelines. He sat down on the ground, waiting for humans to come. He also questioned how Asgore knew he was doing a genocide. He killed the stupid flower, so how did Asgore know about the genocide ? Sans looked at the entrance of the last corridor. A white humanoid figure with no facial features except two red eyes and a red smile slowly approached Sans, who was getting ready to fight.

"You changed," Sans said. The figure just chuckled as two red machete-like swords appeared in its hands. It then blitzed at Sans at unparalleled speeds. Sans wasn't able to react and got sent flying once again towards the city below. Sans immediately got up and summoned a Gaster Blaster under him, starting to fly with it, though a red beam of energy suddenly appeared from the sky right beside him. He barely dodged it. He started to fly at higher speeds as many beams appeared behind him. Then, suddenly, the figure appeared in front of him and kicked him in the abdomen, knocking him from the Gaster Blaster. As Sans crashed, the figure landed on the ground, creating a shockwave that shook the nearby buildings. The figure slowly walked towards Sans. Sans once again fired black knives from all directions, but the figure slashed every single one of them with almost zero effort. Then, Sans summoned black chains, which the figure once again slashed with zero effort whatsoever. There was a sadistic grin on the figure's face ; it was enjoying Sans's desperation. Then, Sans suddenly summoned a Gaster Blaster, which fired a black ray of energy as fast as the speed of light. The figure barely dodged, and Sans used this opportunity to teleport away onto another Gaster Blaster. He snapped his fingers, creating hundreds of Gaster Blasters, all of them firing at once at the figure, who just smiled at Sans. The explosion caused by the blasters vaporized everything in a one-kilometer radius. As Sans looked at the destroyed buildings, he thought he had won, but suddenly the figure appeared and threw a small red orb at him, sending him flying back to the ground and breaking almost all of his ribs. Sans slowly got up, "bleeding" but not of blood, but of black liquid. The figure also landed.

"Ready to give up ?" the figure asked with a demonic tone.

"After all, you know this will end like the other timelines." the figure continued. Sans started to cast black fires, which were a combination of the black substance, Toriel's fire magic, and Asgore's fire magic. He then formed a bow and an arrow out of the fire and got ready to shoot it.

"Make your best shot," the figure said. Then, Sans fired it. As the arrow hit the figure, a big beam of fire appeared, burning every single building in a ten-kilometer radius.

"That hurt a bit," the figure said as it walked out of the flames, summoned a machete-like blade again, and raised its hand in the air to cut it. But then, someone stopped it.