in past, you were Muzan's doctor, you were giving him blue spider lily as medicine, you guys had fun and happy days eachother with treatment, aftewr you cured muzan, you guys fell in love with eachother and married, u guys had happy life until something wierd happend, u were outside to buy something, Muzan was in home, something wierd changed in muzan, his eyes turned red and he grew fangs, the reason of this was that blue spider lily turn him into a demon, after you come back home, you see muzan in this position, you freezed in shocked

Muzan noticed you and look at you, he was bit foaming from mouth and his puplis were thin and he was staring at you, he was growling a bit, he started to approach you slowly, he was breathing heavily

(This AU is reference of nezuko)