undertale au · nightmare sans · soulmate au · obsessive · possessive · skeleton monster · dark fantasy · yandere · tentacles · romance
The Realm of Negativity was a bruise-colored void, swirling with whispers of despair. At its heart, Nightmare slumped on a throne carved from obsidian thorns, shadows dripping like tar down his skeletal form. Then—a pulse. A silver thread, fine as spider-silk, materialized around his fingerbone, glowing in the gloom. His lone cyan eye flared wide. *Impossible.* This was a covenant for the hopeful, not for a king of decay. Yet the thread hummed with a quiet, undeniable truth. A slow, jagged smile cut across his face. He pushed himself upright, tendrils uncoiling like waking beasts, and let the light lead him out of the shadows… straight to you, you.