User blog comment:HELO/How I Learned to Stop Worrying and Love the Catalyst/@comment-24174486-20120710232656/@comment-3581090-20120712140327

You’re right that the Reapers have been the main villain the whole time--which is part of why the introduction of the Catalyst (not the existence of a “catalyst” for the Crucible, but the little Reaper king/cycle maker) in the last five minutes of the game was so anger-inducing.

Because if the Reapers work for the Catalyst, and if the Catalyst is responsible for the annihilation cycle, then the Catalyst is really the main villain for the series and not the Reapers. He’s the head of the snake, the man at the top, the Big Bad, the Final Boss. Unless you beat him, there’s no stopping the cycle. Which is what “stop the Reapers” is really all about.