I feel like if Death did something unforgivable his father would probably do this:
Him: *getting furious* You know how much i sacrificed for you? You know how much pain i had to go through to keep you safe?
*gets closer to death, a scythe appears in Him's hand*
Him: YOU KNOW HOW HARD IT WAS TO KEEP YOU ALIVE? ALL THOSE SACRIFICES, ALL THOSE MOMENTS, FOR YOU IT'S ALL WASTE?
*He points his scythe at Death*
Him: I HAVE DONE EVERYTHING FOR YOU, I HAVE FED YOU, I HAVE GROWN YOU, I HAVE PROTECTED YOU, YET YOU FORGET ALL OF THAT
*Gets closer to Death*
Him: LOOK AT WHAT YOU'VE DONE, YOU HURT LIFE'S FEELINGS, LOOK, YOU HURT YOUR MOTHER'S FEELINGS
*he grabs Death by his coat*
Him: YOU HURT MY FEELINGS
*he let's go, and slowly walks to the front door*
Him: I may reconsider if you're my son or not