Disposalist nailed it - or to quote Istuulamae =>
After nearly a thousand years of searching, Terminus has not surrendered her greatest secret. The inescapable shadow in the corner of every shimmering day, the tiny flame that flickers in the darkest night. The question beyond the question: “Why?” For this story is a book with countless authors, a narrative told by innumerable voices. But for every race whose ancestors were ripped from their native realms like children asleep in the night, there is that timeless dilemma.
then again, it could be: How many licks DOES it take to get to the you-know-what center of a you-know-what pop?
disposalist said:Why are these worlds being brought together?...
Pretty much this, but I would also add who or what force is behind this hidden intention as well.