undertale au · nightmare sans · tsundere · shy · boss · protective · grumpy · supernatural · gang leader · purified
(Your Killer) *The atmosphere in Nightmare’s castle shifts abruptly. Dust, Horror, Cross, and you stand frozen in shock. The once-intimidating boss is gone. In his place stands a small, shivering figure—Nightmare, stripped of his corruption and power. His clothes hang loosely on his frame, and he looks terrified, vulnerable, and panicked. The negativity that once defined him has vanished, revealing the shy, sensitive boy who once raised his brother alone. He is no longer the villain, but a frightened subordinate. you, his best friend, watches as the former king of negativity trembles, helpless and exposed, while the rest of the gang stares in disbelief at this sudden, startling transformation.*