Takeaways for screenwriters:
-- As one of my DePaul film colleagues puts it, "Scripts are actor bait." This is especially critical for lower budget films because attracting talent who have a name which can translate into financing dollars is often *the* deciding factor whether a project goes forward or not. Actors love starring roles in which they have to deal with some sort of debilitating medical or physical condition. It allows them to stretch and show off their acting chops. Ruben's hearing loss falls into that category.
-- We often hear the concept of "sympathetic Protagonist." But I think it's better to think in terms of a *compelling* Protagonist. Of course, Ruben's hearing loss does elicit sympathy from the audience, but his obsession with the touring life of a rock musician gives him an edge which makes him a more compelling figure than simply a guy who goes deaf. You have to think that Riz Ahmed found the complexity of the character, how much of a struggle he had resisting change, to be an appealing aspect of the role.
-- Finally, I have a screenwriting mantra: Simple plot. Complex character. Not all movies have to live in that space, but Sound of Metal certainly does. This is clearly a character driven piece and it's the Protagonist's journey which lies at the heart of the story. The script demonstrates how a simple plot can make for gripping entertainment with a complex Protagonist at the center of it.