This story takes place during episode 12 where Bisco and Milo set out on a journey to fix his body. I haven't read the novel do I'll just come up with something.

(REALLY OLD STORY ITS SHIT COMPARED TO MY OTHERS) What if one day Tanjiro, Inosuke, and zenitsu were requested to live in a big house consisting of all the pillars. Apparently this would help them all when keeping safe during missions and having a good source of food and health treatment. But no one expected it to turn into a competition between demon slayer vs demons The prize you may ask? Well it's Tanjiro's heart of course. (Going through editing currently)

Amidst a violent snow storm up in the mountains, two demons were sent out to extinguish the last living relations to the sun breathers. The Kamados. "Oi stop messing around you woman obsessed freak!" "Come on don't be so up tight!" "Huh... what's this?" A small child appeared from behind a snow covered bush, a small note tied to his neck as his bright red eyes stared at them inquisitively. "Tanjiro Kamado... you don't say" **** "You are to infiltrate the demon slayer corps and gain their trust Tanjiro. I'll always be with you, don't forget that" the demon king stated, his tone surprisingly soft. "Yes father"