Christina Aguilera and Demi Lovato have released their highly anticipated anthem “Fall in Line,” from Aguilera’s forthcoming album Liberation, out June 15th. She has been teasing the collab for months. "I did a collaboration with one of my biggest idols. I can't give away who it is yet, but you'll find out soon," Lovato told Billboard in February. "I can't wait for the world to hear it. It's an incredible song."