A long-asked question in children's literature studies is how the child reads the very same book we (adults) have read. In 1984, Peter Hunt argued for a "childist criticism" proposing that young readers' multiple individual responses to literature should inform adults' critical practice. In this article, I propose that affect theory and new materialist epistemologies could reorient our critical practice in and with children's literature. Using the concept of childist criticism (Hunt 1984, 1991) and Maggie MacLure's (2013) notion of the "wonder of data," I follow different encounters between children (and researchers) and the book "La madre y la muerte/La partida" (Laiseca et al., 2016). This book tells a macabre story about a mother that cannot bear to have her child taken away by Death. By following the book's agency (García-González & Deszcz-Tryhubczak, 2020) in the research assemblage of different projects, I propose possible affective methodological orientations to post-representational research for children's literature criticism.