As a type of written discourse without guaranteed readership and response, protest graffiti nonetheless projects a participation framework in which protesters address different participants, including not only the government but also other potential 'participants' in the social/cultural/political context. This paper studies a dataset of graffiti associated with a protest movement in Macao, China. A survey of the longitudinal data reveals that the contents and visual representation of the graffiti have changed to reflect evolving participation frameworks which are in response to different stages of social movements. While graffiti in earlier stages tends to be more accusatory and anti-governmental, graffiti in later stages shows a shift of protesters' position more in alignment with patriotism and allegiance to authority. Instead of presenting views competing with mainstream political discourse, our data, with their multimodal resources, draw heavily on Chinese cultural discourses which are supposedly shared among the protesters and addressees in this context.