I wanaa drop this just to rediscover and binge read simply because it's too good. Sadly I cannot since I'm already inlove, and addicted; t's a curse. #－.－)
I think Babel is the grim reaper, and it's his job to guide the souls to the next stage, but before that help them finish their mortal businesses. Instead of doing it in a manner as regular grim reapers does, he writes letters that expresses the unsaid thought, and feelings of regret of the souls.