Purpose: The following article examines the playful composing practices of two youth who built on their backgrounds as fan fiction writers, role-players, visual artists and gamers to co-author a multimodal novel across mediated spaces for composing throughout their high school careers. Design/methodology/approach: The study draws on "connected ethnography" and qualitative practitioner inquiry to examine the playful composing practices of two urban youth. Findings: The study demonstrates the playful, multimodal composing practices of youth--for learning, affiliation and leisure. Participants' creative use of digital media reveals robust and productive composing practices that rely on collaboration; extensive multimodal experimentation (e.g. transmediation, the creation of paratexts and worldbuilding); and shared and individual expertise and socialization in various media communities (e.g. gaming and fan fiction). Research limitations/implications: The study is limited by its small scope. Practical implications: Participants' leisure writing activities offer important insights into multimodal play, composing, collaboration and co-authorship. Social implications: Schools have been slow to take up the multimodal and collaborative approaches to writing. The article offers implications for reimagining writing and the teaching of writing through creativity, play and collaboration. Originality/value: The author argues that collaborative, multimodal authorship offers a social outlet, peer connection, and creative possibilities for writing development both in face-to-face and fully digital learning environments, something especially important to consider amid the unexpected surge of online learning due to COVID-19.