Screensaver
A simple on/off control for what your mind returns to when nothing is actively happening. When on, a neutral or steady thought fills the space. When off, whatever is loudest or most repetitive takes over.
Anushirvan and the Walking Dead
Screensaver controls what Anushirvan's mind returns to when nothing is actively happening. Before treating massacre victims, his mental default was probably normal thoughts and entertainment. Now when his mind is idle, it goes to dark places about state violence and trauma. By watching The Walking Dead, he's intentionally setting his screensaver to zombie apocalypse content - something objectively worse than his reality that helps stabilize his mental state.