Usually it has to do with them not being built properly in the first place, or the destruction of those within it. It's sort of resonance. The universe has a few patterns ... let's see. [ holding his hand to his chin thoughtfully. ] Some deities and individuals even play to them, Atropos being one of them. Only more on an omniversal level, and it does make you wonder exactly where they came from.

But "a few years" and "five hundred years" are just comparable amounts of time to us—they could be much different to others. All worlds may not live to the same rules, and therein lies the delicate fabric ready to tear. Of course, that's not saying that all bad ends are because of that, there are a lot of reasons and all framed. Time and space are kind of the same when you think about it.

There's no saying that Atropos and Clotho aren't involved. I'd bank my favorite YA novel on it.