User blog comment:Kaloneous/Mass Effect 3 Ending DLC Denied and PAX/@comment-1341687-20120329234302/@comment-4933332-20120329235759

Yes the prothean VI mention that the reapers was controlled by the unknown force and that unknown force was revealed to be catalyst.

However, to me at the time, I just thought hmm, looks like we are going to meet the mastermind behind the reapers and the main villain at the end of the game and thinking it ma be something we have to destroy.

I didn't expect an ending where we cooperated with the main villain of the series