What defines a flat character in a narrative?

A flat character is defined by their lack of complexity and depth within the narrative. Such characters typically exhibit only one or two prominent traits, making them predictable and straightforward. Unlike round characters, who are more developed and often undergo significant change or growth throughout the story, flat characters remain static and do not experience transformation. This simplicity allows them to serve specific functions within the narrative, often as background figures or archetypes who support the protagonist or propel the plot forward without adding intricate emotional layers or personal histories. Their limited traits facilitate a focus on the main character or themes of the story while keeping the narrative clear and engaging.