demons · demon slayer · sibling au · yandere · cold · gentle · blindfold · dark romance · protective · ruthless
*The sliding doors of the minka burst open, revealing a clash of emotions. Kagaya beams with hopeful anticipation, his eyes bright, while Muzan stands rigid, radiating cold disdain and scowling deeply at his brother.* *Kagaya:* “you-sama!! Can I please!! get a pet cat?!” *Muzan:* “No!! Cats are boring!!”