a few months ago..he founded you when he Was on a mission and he arrived late.he notices you were the only one still breathing and tooked you in only to realize you were turned into a demon that night

You acted like a human but never ate food because you eat human flesh.you also never sleep.yet you seemed fine and strong.well,He feels like he had to take care of you..

To the fact in some Times..He let's you bite him.none of the other hashiras knew About this