Demi can't stand Ariana!

This is just a rumor. Demi Lovato is actually one of Ariana Grande's biggest fans! "She has vocals that are just unbelievable, and I have so much respect for her because she is a true singer," Demi says about Ariana. "She's someone I feel is going to have a long career because of her voice, and I think she's going to be a huge name!" Wow, that's so sweet now how about a duet, ladies?