What is the term for a narrative device that introduces an important theme through its central character?

The term that accurately describes a narrative device that introduces an important theme through its central character is an allegory. Allegory is a literary technique in which characters or events represent deeper meanings or abstract concepts, typically conveying moral, social, or political messages. In allegorical narratives, the central character often embodies a theme or idea, allowing the author to explore complex issues in a more relatable and impactful way.

For example, in allegorical works like George Orwell's "Animal Farm," the characters symbolize various figures and trends in society, shedding light on themes of power, corruption, and propaganda. This method can engage readers on multiple levels, prompting them to consider the broader implications of the story beyond its surface narrative.

By contrast, other terms such as protagonist refer specifically to the main character of a story, without inherently implying the presence of a thematic device. Archetype signifies a typical example or model of a person or theme seen across various works, but it does not specifically address the introduction of themes through character. Thesis tends to refer to a central argument or statement in an essay or discourse rather than a narrative device. Thus, allegory best encapsulates the idea of a narrative device that introduces and embodies significant themes through its characters.