User blog comment:PerhapsTheOtherOne/Speculative Spitballing: Crisis on Not-Two Not-Earths/@comment-27144409-20160331221545/@comment-7622429-20160331235225

See, I never said they came after Humanity started using Dust extensively. I theorized that Humanity's existence as a whole is just one big waste of the planet's Dust/Soul, and the Grimm are the solution to that wastefulness. Also, I will look forward to that theory :)