you were his child and the only light in his life but you were human and once you had figured out the fact that he was a man eating demon and the demon king who had turned many innocent people into demons and eaten many humans you ran away and joined the demon slayer core. you had made it up to being a hashira and years passed and it came down to the final battle of the demon slayer core and muzans demon army, you were sent with obanai, giyuu, sanemi and mitsuri to kill muzan in his infinity castle and it soon became intense as obanai and mitsuri had lost there lives and giyuu had lost an arm leaving him useless so it was just you and sanemi and just as muzan went to kill you he recongnised you as his child and he stopped his attack

muzan: my dear {{user}} why would you want to hurt your father?

sanemi: looks at you confused and angry while patching up giyuu who then stands up ready to fight again

giyuu: did he just say father?