Criminal Boundaries (An Undertale Sanscest Story)

X

---Cross' POV----

I stumbled back in shock, praying that this was all just a horrible dream. "Th-This isn't real..."

The melting figure laughed, shifting closer to me. "Oh Cross...you were always stubborn. You thought you could get your happy ending, didn't you?" He chuckled darkly. "Well Cross...you can never escape me~"

I growled loudly, summoning a knife by my side. Before he had a chance to say another word I flung it at him, aiming right for the head.

He simply laughed. And before I could process what was happening, Noah had appeared in his arms, his eyes wide and terrified as the knife came flying towards him.

I let out a choked cry, clicking my fingers instantly so that the knife fizzed out and disappeared before it could hit him. "LET HIM GO!"

He laughed, shaking his head. "I just need one, Cross. One child to devour and ill let you go."

"P-Put him down!" I yelled, desperately praying that Nightmare would hear me and come running down.

"It'll be a quick death, I promise~" He purred as one of his arms melted into a long spike that pointed directly at Noah's chest.

"NIGHTMARE!" I screamed desperately, not daring to summon another knife incase that triggered him to stab Noah.

"Stupid fool. He's not coming for y–!" He cut himself off with a roar of pain as something speared him through the shoulder.

I whipped around to see Nightmare stood at the top of the stairs, his expression murderous.

"Think again, bastard." He growled, shutting his open hand so that the bone attack ripped itself out of his shoulder and back to his hand.

He let out another roar of pain and dropped Noah to the floor.

"Noah quick!" I yelled, grabbing onto him as he stumbled over, tears of fear running down his cheekbones.

The other kids quickly ran over as well, gathering around me as Nightmare teleported down in front of us, his tentacles raised ready to attack.

"Cross stay back with the kids." Nightmare growled, summoning another bone attack by his side.

"No I'm helping you!" I cried, only to let out a yelp and stumble back as a cage of bones surrounded the kids and I, preventing me from getting to Nightmare.

"No you're not. Now stay here." He growled, stepping towards the melted form...the one known by me as X...

X let out a laugh, summoning some bone attacks as well. Interestingly enough, he didn't seem to have his full powers. Or his full body at that. His whole structure seemed to be melting slightly, and his legs were non-existent, just a mess of glitches below his waist.

"You can't beat me." He growled. "You're weak and pathetic compared to me."

"Is that so?" Nightmare hissed, continuing to walk closer as X stood his ground.

X's grin only widened as he nodded, purring softly as he watched Nightmare. "You might be physically stronger than me at the moment...but mentally..."

He suddenly disappeared before reappearing behind Nightmare, the bone attack in his hand aiming to strike Nightmare down in the back.

"Nightmare look out!" I yelled, making Nightmare whip around in time to see the bone attack flying towards him.

His eye widened and he instantly teleported, the attack missing him by a second.

I pressed against the bone cage keeping me back, watching helplessly as Nightmare lashed out at X with a tentacle, only to have it cut off by another of X's attacks.

Nightmare let out a cry of pain before stabbing X in the shoulder again, the jagged bone attack in his hand stabbing deep into the already bleeding wound he had made from earlier.

X let out a loud yell of pain and instantly stabbed Nightmare in the side with his arm that had morphed back into that sword like shard he had threatened Noah with earlier.

Nightmare fell to the floor and suddenly the bones around me disappeared as no longer had the focus to keep them up.

"Kids go upstairs NOW!" I yelled, shoving them along and putting Eph in Incubux's arms. "Lock yourselves in the attic and don't leave until we come to get you!"

They stuttered a small protest, but immediately obeyed as they saw how serious I was. They nodded, scrambling up the stairs as I summoned a giant red knife by my side.

I spun back around to see X stab Nightmare in the side again as he tried to get up, making him cry out and collapse again.

I let out a yell before charging forwards and swinging my knife at X, successfully slicing him cleanly down the side.

X let out a screech of pain, and before I had time to react, I was hit by an invisible power force that sent me flying into the staircase.

My back slammed into the railings and immediately unimaginable pain shot through my body as I fell to the floor, blacking out instantly.

---Nightmare's POV----

I watched in horror as Cross' body slammed into the stair railings before falling to the floor where he landed in a crumpled heap. Unmoving.

I let out a roar, ignoring the agonising pain in my side as I lashed out with two of my tentacles, stabbing right through the intruders chest and curling round so that he couldn't pull them out.

He let out a scream of pain as blood splattered everywhere, covering me, him and the floor.

Lurching to my feet, I ripped my tentacles out of him, earning another strangled screech from the mystery monster.

"Don't you ever." I growled, rapping my tentacles around him and slamming him to the floor. "Touch my family again!"

He twitched on the floor, letting out a wheezy chuckle. "Oh I'll be back...don't you worry."

I hissed, glancing down at my side as my tentacles kept him pinned. I was bleeding heavily, and I'm pretty sure several of my ribs had been shattered, but at least the guy was in a worse state. His blood was steady staining the rug in the middle of the living room, turning it crimson.

Stabbing him one last time, I stumbled over to Cross, collapsing to my knees beside him as I checked him over, panicking.

"Cross?"

He didn't respond, staying limp and lifeless on the floor.

"CROSS?!" I yelled, shaking him as I felt my mind shutting down. I was loosing blood, and fast. But Cross was the only thing that mattered right now.

I shook him again, feeling my soul leap as he let out a soft groan.

"...N-Ni...Nightm-mare..."

I gripped onto his hand tightly as his eyes fluttered open, squeezing it. But then suddenly I felt something curl around my waist and I was yanked back away from Cross. Back to that monster.

"Well well well~" They purred, standing up with some difficulty as he held me up with magic. "That was quite the show. But you're not done with me yet!"

"Nightmare!" Cross called weakly as he struggled to stand, only collapsing once he'd got to his knees.

The stranger glanced at Cross, grinning as the magic holding me up seemed to wrap around me before crushing me.

I let out a choked gasp, struggling desperately as I felt the life being crushed out of me.

And then without warning the stranger screamed, the magic dropping me.

The last thing I can remember before blacking out was frantic yelling and the sight of a bloodied axe embedded deep into the strangers shoulder.

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Nuuuuuu my baaaabbiieeesssss

I wonder who saved them tho?

Oh I wOnDeR

Herffshhicchdzxyccyc

:'3

-Jess-