Courage stems from the Latin word cor, meaning "heart", which is often seen in other words like cordial or accord..  The term derived from the Vulgar Latin word coraticum (a noun indicating a state of being).  Originating in 12th-century Old French as corage, originally described one's spirit, mood, or heartfelt emotions.  It appeared in Middle English around 1300.  The term originally meant "innermost feelings," "temper," or "spirit" and evolved from "heartfelt expression" to mean bravery, valor, and confidence.  The word was historically used to describe bringing all of one's heart into a situation, rather than simply acting in a heroic manner. 

According to the Oxford English Dictionary (OED), the earliest known use of the noun courage in English is around 1300.  It appeared in the Middle English period (1150–1500), derived from Old French (corage).  The OED highlights the appearance in Kyng Alisaunder (c. 1300), a Middle English poem.  The earliest recorded adjective courageous is dated slightly earlier to roughly 1290 in the South English Legendary. and later, the adjective form courage is noted in Promptorium Parvulorum around 1440. 

A character's courage is essential for driving the plot, fostering reader empathy, and establishing a compelling theme.  It forces protagonists to confront fears and overcome obstacles, transforming them from passive observers into active agents who achieve their goals, while demonstrating that true bravery is mastery over fear, not its absence. 

Key roles of courage in storytelling include:  
Driving Action and Agency: Courage allows characters to make decisions, take risks, and actively drive the story forward rather than being victims of circumstance. 
Creating Relatability and Growth: Showing a character's internal battle—facing fear and proceeding anyway—makes them human and relatable. 
Developing Key Themes: Courageous actions, such as choosing what is right over what is easy, turn thematic concepts into lived experiences, strengthening the story’s message. 
Character Transformation: It drives the hero's journey, forcing characters to confront limitations, grow, and often, to save others.