Supporting a relational approach to publics and the concept of the political, this thesis examines how the climate-striking teenager Greta Thunberg comes into being as an activist citizen through acts of citizenship and, in turn, how these acts are transformed in a network of connections. Drawing on Isins (2002; 2009) understanding of the political as a producing act, we find that Greta Thunberg applies both affiliating, agon and antagonistic orientations to develop frontiers to her crisis discourse on climate change and enable a public. Doing so, she constitutes herself as an activist citizen by claiming rights to survival in the wake of climate changes and, thereby, transforms the fields of contestation by creating ruptures in the social. Combining Isin & Rupperts (2015) view on the internet with Warners (2002) concept of publics, we find that other political acts also reconstruct Greta Thunberg within both agon, affiliating and antagonistic publics in the Danish press and argue that these acts work to both legitimize and delegitimize the rights claims enacted by Greta Thunberg. Finally, we conclude that such acts are an inevitable possibility of being political in the public eye.