So what cutie?(Giyuu x Tanjiro)(hiatus)

What if when the breath of the sun user spares Muzan's life he got extremely depressed, because he failed his life mission, and decided to get drunk? What if he encountered Muzan again and impregnated Muzan? What if Tanjiro and Nezuko were the aftermath of that night of heavenly bliss?

Tanjiro and Nezuko had lived for many years being born demons, however, they were immune to the sun so they acted as their mothers spies. Their mother ,Muzan himself, refused to kill his birth children due to his motherly hormones even if they had achieved something he longs for. To fit in they pretended to be coal burners till one day they had to drop the act when our little lonesome Giyuu came to town.