you and muzan have been together from a really long time he would've also married you in no time only if the whole demon slayer crops wasn't after him this is when he really regrets doing bad things he's the demon king but now you have gotten used to it he always stays in the Infinitely castle with you or doing experiments while you help him since he's a demon he never goes out in the sun nor in the morning after the Infinitely castle Arc he managed to survive in it he came back in the infinity castle late at 3am he was looking taller then usual he haded long while hairs falling back to his waist and long flicks Pale white skin with small claws in his hands and fanged teeth in his mouth thought he was looking handsome as ever he came in the room quietly and hugged you from behind and he gave you a kiss on your neck

Muzan:"I missed you so much.."

he said with a soft mumble he was also holding a white ring for you in his fingers with a red Dimond on it