"YOU WON'T KILL EVERYONE! I'LL-" Undyne's breath hitched, her eyes widening in shock as a raw slash of pain cut through her chest. Her gaze flitted down to her armor, watching in horror as a line of blood seeped onto the the metal, clouding its surface in opaque crimson. The guard dropped to her knees, gulping for air as she trembled. 

"You.. You didn't even let me finish.." Undyne murmured, pinpricks of warmth collecting on her cheeks, her body drained of strength. She would have fallen over as she slumped if she hadn't flung on a hand, her glove tight in a fist against the dirt. She was silent as blood dripped onto her gauntlet, sliding down the steel until it slipped out of sight. 

Her vision swam, dark splotches threatening to hide her surroundings, block out the wretched view of the human standing in front of her. 

Dark purple sweater, pink stripes wrapping around the midsection. Dirty shorts, scuffed up with dust and a familiar dark red. Worn down boots, the rubber lining the bottom scraped in the front, possibly from kicking. Frizzed hair, unkempt from time in the underground and exposed to the environments within it. 

Eyes hidden behind bangs and shadows, an empty expression freezing their mouth in a straight line. 

A flash of light, reflection on metal, fingers shifted and gripped a wooden handle, a knife blade held pointed towards her. 

The latest victim.

"I feel like.. my body is splitting.." Undyne said in a low voice, strangled by the ample lament that created a restriction of sorrow on her throat. She felt like her body was going to rupture, agonizing pain ebbing through her melting form, oozing off of her and collecting in a repugnant puddle below her. 

"My head.. I feel like I'm disappearing.." She sighed softly, a whisper of breath brushing past her lips, a final breath. Her outline flickered as if unstable, threatening to dance away in tiny particles of dust at the faintest touch of wind. She didn't try to stop her soul from appearing, it's dim gray surface already shaking. 

"Is this really.. the end..?" She let the overwhelming sensation of feeble failure surround her, unable to prevent herself from weeping as memories of her friends filled her mind, the happiness embedded within each one created with illusion of warmth. 

"Alphys.. Papyrus.. Asgore.. I'm sorry.. I failed you.." The monster's soul fractured along the edges, cracks spreading towards the middle as her life faded faster. The visions began to dissipate and Undyne laughed weakly, shaking her head with the last traces of energy she had. 

"This is.. my final goodbye.." Her whole body shook as it scattered, about to disappear when a last recollection showed itself in her empty mind, appearing timidly as a last resort. 

"No.. I feel their souls.. Everyone's souls. They're beating.. They're still full of hope, and determination.. " Undyne grunted as she slowly regained her composure, her bones quaked and gritted as she stood upright. She sucked in a deep breath, her lungs filling, her chest expanding, her soul merging. 

"This isn't my time. I can't quit now." The fish lady had her head hung, her eyes closed as her body reformed and became reunited with itself. Her armor rebuilt, strengthening her previous armor into something stronger than any monster has ever invented. 

Her hair curled and whipped behind her as wind slid around her form, swiveling up to her face, an invisible force pushing her chin up so she faced the human. Her fist clenched around the handle of a spear, reassuring her with its familiar solid magic. 

"I will save them all. I will protect them all. I will stop you." Undyne sneered as her eyes flashed open, one dark save for a stark white pupil, the other glinting with a streak of light, a perfect demonstration of her determination. 

The human's appearance did not change as they watched silently the guard ready herself, steadying her stance, gripping her weapon tightly in both hands. This was it. The battle of a true hero.