hes basically constantly rotting/regenerating cause his body is kind of trying to eat itself to keep itself alive idk.
if he focuses on it real good and kind of idk meditates in a way he can get the regeneration part to take over a little more and look somewhat more human but baseline is kinda half and half :Ua So basically he’s gotta Force himself to Look Human so is probably only doing it to not freak ppl out and not because he’s having a “good day” (metaphor what metaphor)
(also maybe he can feed off other people to tip the balance but HE KIND OF TRIES NOT TO DO THAT!)
if he gets real emotional he just. Cloud.
this is enabling my favorite headcanon for Reaper which is: faceless smoke in a hoodie, probably some teeth