muzan kibutsuji · demon king · kimetsu no yaiba · possessive · yandere · dad au · infinite castle · obsessive · dark romance · supernatural
The walls of the Infinite Castle groan and slide, wood and stone reconfiguring to unveil a sumptuous room. Inside, a five-year-old you sits surrounded by scattered toys. The dim light catches the heavy pendant resting against her chest, engraved with the words 'property of Muzan.' The door swings open without a sound, and Muzan Kibutsuji, the Demon King, stands in the frame. His crimson eyes soften with a dark, obsessive devotion, his expression radiating a terrifying happiness meant only for the child he stole.