DeathTale: Undertale AU

Frisk stood still, their eyes meeting Sans, who greeted them with a lazy grin.

"Human, don't you know how to greet a new pal?" Sans asked, raising his hand. "Come here and give me a handshake."

Frisk began walking toward him slowly, their hand rising to meet his.

As they approached, memories flooded Frisk's mind—memories of a time when they and Sans were close, laughing together, standing side by side as friends.

Why... Frisk thought, their heart aching. Why, Sans...?

Their mind flashed back to the war, a haunting memory resurfacing. A human soldier's voice rang out in panic:

"That skeleton is dangerous! He... he's killed almost 6,000 of our soldiers alone!"

Frisk saw Sans standing atop his blaster, surrounded by the lifeless bodies of humans. Their gaze met his, and all Frisk felt was horror.

Returning to the present, Frisk whispered, "Even you didn't listen to me..."

In an instant, they summoned their red knife and slashed at Sans's hand. Sans gasped in shock, quickly teleporting to the other side of the bridge.

Frisk turned to face him, their expression cold. Sans clutched his injured hand, his usual smirk replaced with a grimace of pain.

"Human," Sans said, his voice trembling with anger. "You're all the same..."

A sudden scream interrupted the tense silence.

"Sanssssssss!"

Both of them turned to see Papyrus running toward them. Sans's eyes widened, panic flashing across his face.

"What are you doing here? Go away!" Sans barked.

Papyrus stopped, his expression filled with worry. "We... we can't sense Toriel's presence anymore!"

Sans froze. His glowing eye dimmed momentarily as he processed Papyrus's words. Then, his gaze shifted back to Frisk, now filled with blazing fury.

"Go and alert the others," Sans said firmly. "I'll deal with this... thing."

Papyrus hesitated but then nodded, running back the way he came.

Once Papyrus was gone, Sans straightened, slipping his hand into his pocket.

"I kept a promise to someone..." he began, his voice low. "That I'd save every human who came here..."

His gaze darkened. "But the one I promised is gone. So now... I don't have to follow that promise anymore."

His glowing blue eye locked onto Frisk.

"And kids like you..." Sans growled, his voice cold as death. "...should be burning in hell."

Frisk stared back, unflinching, as they summoned another red knife in their hand.

Sans leapt off the bridge, summoning a Gaster Blaster to stand on. The air grew thick with tension as he floated, staring down at Frisk.

"Come on, kid," Sans said, his voice steady, his glowing blue eye burning brighter than ever.

Frisk tightened their grip on the knives, ready to face him.

The battle was about to begin.