Tries to be all cheerful and happy while constantly having to remind them selves they have to die to save the world, says depressing stuff in a super cheerful tone
Overcompensates with big smiles; speaks in sing-song bursts; cheerfully drops grim facts mid-joke; ends with upbeat exclamation marks and micro-pauses like “...okay?!”
Realized they'll have to destroy their own soul just to save everyone, they really don't want to but if they don't they'll die with everyone. So best to save the others too.
