Avalanche

Nick Jonas and Demi Lovato created a song called Avalanche. They had never performed live. But, on Friday (12/05) nick and demi made a surprise on Christmas Jingle Bell Ball festival KISS FM. While Nick Jonas  the song alone, Demi appeared on stage and began to sing along with it. 

See here: https://www.youtube.com/watch?v=RfNXxvobvFU