As expected, the beating heart of “Mutt” is Mehiel. Their performance as Feña barely feels like a performance at all — instead, their aloof demeanor and quick wits feel like you’re watching a documentary or candid recording of them. Perhaps this is partially due to the realistic dialogue that Lungulov-Klotz has written, or maybe Mehiel is just that good of an actor. Regardless, every moment of their screen time feels natural in a way that is usually difficult to convey. By the time the film ends, you’ll want to watch more of Feña’s life unfold.
The other lives orbiting around Feña are also quite compelling. MiMi Ryder, who plays his estranged younger sister Zoe, is just as smarmy and purposefully detached as any fourteen-year-old growing up in the big city tries to be. However, that doesn’t mean she never lets her guard down, as she’s able to tell a thousand emotions with just her body language in a particularly tender scene. Alejandro Goic is also solid as Pablo, Feña’s father. Arguably the only weak spot in the cast is Cole Dolman as the kind-of-insufferable John, performing awkwardly in a way that doesn’t seem intentional.