DeathTale: Undertale AU

Frisk hurled the black knife toward Sans with a swift motion, the blade cutting through the air like a vengeful specter.

Sans, desperate, summoned an army of bones and Gaster Blasters to shield himself. Using his magic, he propelled himself into one of the blasters, which carried him into the sky.

But the knife was relentless. It sliced through the bones and disintegrated the blasters, relentlessly pursuing its target.

Sans readied an energy blast, intending to destroy the knife mid-flight. But just as the blast was about to hit, the knife veered off course, circling behind him.

"What the—" Sans began, but his words froze in his throat as the knife transformed into a portal.

Frisk emerged from the portal in an instant, appearing directly behind Sans.

Sans tried to teleport, but it was too late.

Frisk's black knife pierced his chest, and his glowing white and blue soul was forcibly extracted. Sans stared at Frisk, his face etched with disbelief and sorrow.

Frisk met his gaze with a cold, unfeeling stare.

Sans's form began to crumble into dust. "Kid..." he whispered, his voice weak.

In silence, Frisk caught Sans's soul, encasing it in a black aura. Slowly, deliberately, they absorbed the soul into themselves.

As Sans's dust scattered to the winds, Frisk descended to the ground. They stood motionless, the battlefield eerily quiet.

After a moment, Frisk raised their knife once more, slashing through space and time. A swirling portal appeared before them, and they stepped inside.

---

Underneath the towering barrier gate that sealed the Underground, Asgore sat in solemn silence. His gaze was fixed on the gate, his posture weary yet resolute.

Suddenly, a portal tore open behind him. Asgore turned to see Frisk emerge.

"So, you've finally come," Asgore said, his voice deep and steady.

Frisk stood silently, their knife glowing faintly in their hand.

Asgore rose to his feet, towering over the child. For a moment, the two locked eyes, the air between them heavy with unspoken tension.

"I suppose you're here for this," Asgore said, gesturing toward a pedestal where seven glowing human souls rested. Their ethereal light cast a haunting glow over the room.

Asgore sighed deeply. "I might have made mistakes... terrible mistakes. But there's one thing I've never done: I've never killed the one I loved."

Frisk's expression didn't change, but their eyes narrowed slightly.

Asgore continued, his voice tinged with both regret and defiance. "You're wondering how I know about you, aren't you? The truth is, I don't know everything. But I know enough. We aren't strangers, are we... human?"

Frisk summoned their knife, the blade radiating with a menacing aura.

Asgore nodded solemnly, gripping his red trident as he donned his battle armor.

"Very well," he said, his voice firm. "Let's end this. Right here. Right now."

Frisk and Asgore faced each other, weapons at the ready.