DeathTale: Undertale AU

Frisk dashed toward Sans at full speed, their red knife gleaming with power.

Sans summoned a Gaster Blaster and launched a beam, but Frisk easily dodged.

"I've seen that a million times," Frisk muttered coldly, their eyes filled with resolve.

They hurled the red knife toward Sans. He quickly summoned a wall of bones to block it, but the knife, fueled by Determination, pierced through the bones effortlessly and struck the blaster Sans was standing on.

Sans jumped off just in time, using his blue magic to grab Frisk and slam them into the ground. He followed up by summoning a barrage of bones and sent them hurtling toward Frisk.

Frisk countered by summoning a swarm of red knives, colliding them with the bones mid-air. The clash caused a massive explosion that shook the battlefield.

Sans quickly summoned more Gaster Blasters, preparing to unleash another wave of beams, but Frisk was nowhere to be seen.

He scanned the area, only to sense danger too late—a red knife narrowly missed him, striking one of his blasters instead.

He turned to see Frisk sprinting toward him. Reacting swiftly, Sans used his blue magic again, slamming Frisk into the ground once more. This time, he summoned a massive bone spike, aiming it directly at Frisk's center.

The spike struck true, impaling Frisk.

As they lay pinned, blood pooling beneath them, Frisk's mind raced.

(I don't have enough LOVE to defeat him... What should I do? Should I reset and try again?)

Frisk hesitated. No...

(I already know what will happen. The same thing. I'll save them, and they'll start the war again, killing themselves...)

Their breathing grew ragged, their grip on the knife loosening.

(If I don't have enough LOVE... then I'll... I'll just make it myself...)

Sans, panting heavily and drenched in sweat, stood over Frisk. Summoning his blasters, he unleashed a devastating barrage of beams that engulfed Frisk, reducing their body to ashes.

Sans landed on the ground, exhausted. He wiped his brow, relieved the battle was over.

"Finally..." he muttered, turning to walk away.

But a chilling sound echoed behind him.

"But it refused."

A deafening explosion erupted, shaking the entire Underground. Sans turned around in shock to see Frisk, standing completely unharmed, their body radiating a dark, otherworldly energy.

"What...?" Sans gasped, his eyes wide.

Frisk's mind screamed with raw emotion:

Determination. My hate. My will. My anger. I'll combine it all. I'll become Determined!

The air quaked violently around them as a notification appeared in their vision:

"LOVE increased."

"LV 10,000"

"LOVE increased."

"LV 99,999,999"

"LOVE increased."

"LV 999,999,999,999,999"

"LOVE increased."

"LV ♾️ (infinite)"

Frisk's red heart of Determination morphed into a pitch-black core, pulsing with unimaginable power.

They landed softly on the ground, their eyes now glowing a menacing red.

Sans staggered back, his usually calm demeanor replaced with fear.

"This thing... isn't human," he whispered, gripping his blasters tightly as he prepared for the fight of his life.