User blog comment:The Milkman/Indoctrination Theorists Say the Darndest Things, Part II/@comment-98.240.62.123-20121205063937/@comment-24174486-20121205130241

Well, is Control want the Reapers want? Obviously not. They are sentient beings, and somehow I doubt they would want to have their minds overwritten. It wouldn't necessarily do anything to end the need for the Reaper cycles.

Is Synthesis what the Reapers want? Actually, the Reapers don't try to achieve Synthesis—it is the Catalyst who offers the option. Synthesis being a possibility doesn't stop the Reapers from attempting to destroy the Crucible, even when the Catalyst tells you about it and how it would solve its problem. While Synthesis ends the need for the Reaper cycles, it is not what the Reapers want; it is what the Catalyst wants, and we see that the Reapers and the Catalyst are different entities.