It was Merlin’s idea to take control of the Archway, and add a way to control it. Possibly utilize Dementor’s or at least something from them. I was so vehemently against it, until he figured out a way to use their essence. The usage was far too important than my fears. At that point, I only allowed him to handle the specters, unless he wanted them dead. Then I was the one doing the killing. In hindsight, we never should have moved the Archway and kept it closed. There were far too many Dementor’s in the world for my comfort. 