This study presents a computational analysis of Italian fanfiction, aiming to construct an interpretable model of successful writing within this emerging literary domain. Leveraging explicit features that capture both linguistic style and semantic content, we demonstrate the feasibility of automatically predicting successful writing in fanfiction and we identify a set of robust linguistic predictors that maintain their predictive power across diverse topics and time periods, offering insights into the universal aspects of engaging storytelling. This approach not only enhances our understanding of fanfiction as a genre but also offers potential applications in broader literary analysis and content creation.