Meet the Star-Studded Cast of Life Itself, aka This Is Us The Movie

In the trailer, we see Monner running with a piece of paper and smiling at a library. Given that he's a younger character, he might be Olivia Cooke's romantic interest. Monner is known in Spanish television for his lead role as Lleó in the Catalan comedy-drama series Red Bracelets (not the U.S. adaptation, The Red Band Society).