With all the high drama and decadence in the lyrics of his dark but compelling tracks as blackbear, it's amazing Matthew Musto has any time to work. Yet the heavily tattooed singer and rapper who became one of the 2010s' biggest online breakouts remains equally productive as a composer and producer. As he demonstrates with a list of clients and collaborators that includes Justin Bieber, Miley Cyrus, Gucci Mane, Rivers Cuomo, and Mike Posner, he's a multi-tasker who can cross any remaining divide