Sans was sitting on his bed piddling with his tiny fingers
He felt something twisting inside
Him like he wanted to do something a twisted smile formed on his face
He went to the kitchen and got the sharpest knife and he hid it in his hoodie pocket then he went to the garage and he found Undyne practicing with her spears Sans entered without Undyne seeing him and he just stood here waiting patiently
Undyne saw Sans and she got startled "Ah , oh it's just you " Undyne groaned in annoyance
"Hello undyne~"Sans purred
"Ugh what do you want?"Undyne said impatiently
"I just want to play with you" Sans said creepily but in a childish way
"Why would I play with someone like you"Undyne growled
"I'm just a kid Undyne"Sans faked disappointment
"Just get out of here"Undyne yelled at him oh she made a mistake
Sans shut the door with his telekinesis
"Sans...?"
He took out the knife and smiled a twisted smile the strange thing that his eyes were shining red
Sans stabbed Undyne in her stomach she screamed Sans put his much smaller hand on her mouth to shut her up
Undyne was trying to fight back but Sans was much stronger sans stabbed her chest repeatedly and blood kept splattering on him
And he twisted the knife inside her chest
Sans made sure that Undyne was limb but a glow filled the place
Oh it was Undyne the f*ing Undying
"You have to try a li-"
She was interrupted by Sans slashing her across the chest and not just that it decreased all of her HP she wasn't fighting a monster she was fighting a demon
"No I don't have to" Sans said in a creepy voice his eyes were dark he left the garage he knew that boss monsters take some time before turning into a dust
Sans teleported to his room he changed his bloody clothes and put on clean one he burned his bloody clothes with his Gaster Blaster
"Undyne is dead" Alphys said with tears in her eyes Everyone gasped and Sans was faking surprise
They went to the garage and found a Undyne's dead body lying in a pool of blood and so many broken spears
"Who would be heartless to do this What did she do to deserve this?"Asgore said sadly Everyone cried for their lost heroine
They called the police "So are you telling that you found her dead?" One of the cops told Frisk she nodded shakily Frisk never saw something horrifying like that
"OK the murder is smart there's no fingertips on the knife or the spears" the man said concerned
It was true Sans is not an idiot he wiped his fingertips from the knife and he broke the spears with his magic
But that doesn't mean he wasn't worried about someone finding out
"But from the depth of Undyne's scars looks like the knife was heavy for the murder and their hands is kinda small she was killed by a pre-teen who under the age 15" the man explained
Sans crused under his breath this officer was smarter than he thought he have to get rid of him
"We will inform you if we found any evidence"
Before the police officer was leaving Sans pointed to him
"Hey I might have something interesting"Sans said calmly
The man followed him and Sans looked at him with twisting smile
"Good bye"
Before the officer could defend himself he was killed by a Gaster blaster
Yay the first murder scene actually my headcanon in this story that boss monsters take a long time before dissolving into a dust that's why the officer could check Undyne's cropseThat scene was inspired by @Mini_Crushies's story corruption on Wattpad when Luan killed Luna and framed Lynn but I didn't make Sans frame anyone cause he wants all of them dead