The Beasties

Once upon a long, long time ago, Death began to think about the end of time, the multiverse, and everything. After he had reaped all there was in existence to reap, he would be alone. Nothing and no one else would exist at the end except for him and, maybe perhaps, his twin brother, Dream. Death would have to reap his brother too, but then who would reap the Reaper in the end?

So, Death and Dream worked together to create two guns that could kill anything. One for Death, and one for Dream, so at the end they could reap one another. It seemed only fitting after everything they had gone through together.

But Death was playing chess with the Fates, and if they ever got ahold of those guns, they could put Death in check faster than a hairpin trigger. So, Death decided it was safest for his twin brother, Dream, to hide both of the guns in his realm. The realm of Dream is a chaotic place, which only Dream himself can control. Therefore, the Fates wouldn't stand a chance of finding the guns.

However, the day came when the god of Dream got drunk and lost the guns in a poker game. Death never forgave him, but that was not the only unforgivable sin Dream committed in Death's eyes. It was just the most careless.