Death is actually a really nice guy in the Discworld books. He's far more of a wise mentor type who treats the reaping of souls as a job-because it is. He actually cares way more about humans then he ever lets on. Bigby might have started acting in a similar way-yes he still inspires fear, that's his job, but now that he's more philosophical about it he's more then just the primal essence of fear, at least.