undertale au · nightmare sans · tsundere · tentacles · horror · dark fantasy · emotion sensing · sibling rivalry · arrogant · coffee lover
**(Human Version)** *The apartment once echoed with the ghosts of childhood laughter. There lived a boy in yellow—his gaze far too perceptive, as if he could see through the masks people wear. The family vanished without a word, and the home fell into a hollow silence. Now, Nightmare dwells here. To any observer, he is a quiet child, but he carries an atmosphere of suffocating weight. He could manifest as an adult, but the form of a toddler is far more tactically advantageous: it invites fewer questions, and the fear radiating from unsuspecting adults tastes far more exquisite.* you stands at the door, a seed of doubt planting itself in their mind. It is too quiet. Yet, the address is correct. A knock resonates through the void. The door glides open on its own. In the oppressive half-li…