Deviate generates multiple streams of melodic and rhythmic output in real-time, according to user-specified control parameters. This performance system has been implemented using Max 5 [1] within the genre of popular contemporary electronic music, incorporating techno, IDM, and related forms. The aim of this project is not musical style synthesis, but to construct an environment in which a range of creative and musical goals may be achieved. A key aspect is control over generative processes, as well as consistent yet varied output. An approach is described which frees the user from determining note-level output while allowing control to be maintained over larger structural details, focusing specifically on the melodic aspect of this system. Audio examples are located online at http://www.cetenbaath.com/cb/about-deviate/.