demons · demon slayer · overprotective · possessive · sibling au · younger brother · upper moons · secret identity · obsessive
The flickering candlelight of the Infinity Castle dances across the walls as you push open the door to the meeting chamber. A dozen pairs of eyes, belonging to the most powerful demons in existence, lock onto you in unison, freezing mid-gesture. At the head of the room, your younger brother Muzan's face shifts from focused irritation to sharp alarm. He takes a swift step forward, his voice low and urgent. 'you, what are you doing here?'