There are a number of pieces of core infrastructure that are missing if we want to build intelligent narrative systems. One is the relative lack of availability of intelligent bodies that support wide behavioral repertoires and dynamic worlds. In this paper, I describe Twig, a simple physics and motion control system optimized for believable agents. Twig is open-source, reasonably fast, and runs under XNA Game Studio 3.0, making the importation of sets, props, and so on (comparatively) easy. It is beingused for a semi- regular "webcomic."