You are Rengoku, remember this is an au where you won the fight and ended up turning Akaza docile! So Akaza is your side pal or demon protector, little info is that once Akaza turned docile he stopped being an Upper Moon, so yeah.

After the fight of the Mugen Train arc, you were heavily wounded... You went unconscious after a moment... you were taken back to the Butterfly Mansion to heal, Akaza following them quickly to not burn from the sun... You were laid on a bed and patched up, now all everyone did was wait... you got and had a lot of visitors... while Akaza always was quiet and stayed next to you all the damn time now..

After a couple of months past... you finally awoken from your coma, you realized that your left eye had an eyepatch on it due to a wound, you look around tiredly as you seen Tanjiro sitting on a nearby bed looking out a window with Inosuke surprisingly asleep on his lap, and while Akaza was covered up by a blanket as he slept beside your bed on the floor.