Somnum Exterreri - short story, horror

[Prompt from reedsyprompts: Write a story involving a character who cannot return home]

It was the slight jarring of my chamber door that awoke me, the night already approaching its latest hours. The heavy thing slowly dragging against the flooring, the metal latch clinking ever so lightly, the incomparable scratching of nails on wood; an orchestra of sounds in the span of mere seconds. I did not see it occur, no- as the remnants of sleep still held my consciousness in its grasp and the available moonlight filtering throughout the room was shrouded by the thick covering of somber clouds.

Beyond the door, leading to a hallway, was a sliver of blackness. A pitch of dark against the already dreary scene, the kind to slither over your limbs and entrance you into motion until you are completely submerged, the kind that appears soluble; as if it were its own entity merely standing there, motionless, in the threshold of my room.

With haste I sat up, allowing the woven quilt to fall to my lap. It was a strain to see any fine details through the thickness of night that blanketed my room, my vision only allowing for meager outlines and silhouettes. I waited with bated breath as I stared, my eyes widened in hopes of capturing the disturbance that roused me. The longer I stared at this mass of onyx, the faster my own heart began to beat. A steady rhythm crescendoing to an unknown tempo as what started out as a sliver began to seep inside my chamber like a serpent through grass. It scoured the walls, expanding upward and out like the blue veins inside one’s wrist. The mass sprawled itself along my floor, flattening out until the hardwood was coated in a thick layer of utter nothing.

I scooted further up my bed as my hand reached to my bedside table, desperate for the matches I stored in the top drawer. As my hand retracted, it skimmed the approaching edge of black.

“AH!” I cried in pain, matches falling into the accumulating pool of darkness as I cradled my hand to my chest. The feeling was excruciating, as if the burn of ice and fire were to coexist in a contained form. I looked on with horror as thin, black veins appeared to sprout from the point of contact, wiggling under my skin like maggots through rotted meat. My hand began to go numb, twitching with the feeling of pins and needles pressing ever so slightly against my nerves. I had to get out of this hell.

But how was I supposed to escape when surrounded by such a vile substance? Where was I to go? It had slowly begun to climb the windowsill, the only traces of light being taken away before my eyes as I begged it to stop.

My will to escape was replaced with desperation. I screamed from my place on the bed, clawing at the sheets with anxiety as I hollered. I could feel the veins in my neck budge as I screamed, tears spilling down the side of my face as I pled. Useless.

I fell back with a sob, body straightening out save for my hand which had begun to curl in on itself, my bones themselves starting to curve. The veins were now tracing and swirling up my arm, the slight sting following in its path.

With one last plea, I closed my eyes. I felt the edges of my toes begin to curl at the feeling of frigid breath fanning over them.