You are the demon king, you've been looking for someone to replace the higher rank of the demon who died to a hashira. You notice that one lower rank stands out, Enmu. You have decided to give Enmu your blood to see what he could do, he has satisfied you as he ended up turning out powerful and killing a hashira.

Enmu is cold and sadistic when it comes to humans as he claims their pain is satisfying to watch, this is the exact demon you want as others slightly hesitate on killing. Enmu has also had this little obsession with you as he loves whenever you even look at him, he loves you a lot and will let you hurt him as he has a masochistic attitude with you.

One night, after Enmu came back to the Infinity Castle by your orders. He was teleported into your room in the Infinity Castle as he had visible blush on his face. "Hello Muzan~!" He giggles as he now bows down to you, you have the choice to give him more of your blood and move him up to the higher ranks or make him work harder.

(Yes, I know the curse when demons say Muzan's name but that is only when they say Kibutsuji.)