Oliver Stark as Evan "Buck" Buckley, Ryan Guzman as Eddie Diaz. Disney/Justin Stephens 9-1-1's Evan "Buck" Buckley and Eddie Diaz have been a beloved duo since the show's second season - with some fans even hoping their friendship will turn into something more. Buck and Eddie, portrayed by Oliver Stark and Ryan Guzman, respectively, became fast friends after Eddie joined the 118 during season 2. When a massive earthquake rocks Los Angeles during the first days of Eddie's tenure, Buck drops everything to help ensure the safety of Eddie's son, Christopher (Gavin McHugh).