Steadfast originates from the Old English word stedefæst meaning "secure in position", "firm in place", "firmly fixed", "constant", or "immovable".  It is a compound of stede ("place," "position," or "stead") and fæst ("firmly fixed," "fast," or "secure"). It emerged before the 12th century to describe unwavering loyalty, resolve, or a fixed physical position.  Used in late 10th-century Old English (e.g., The Battle of Maldon) to describe soldiers holding their ground.  Historically, it referred to being physically unmoving in battle, later evolving to mean unwavering in purpose, loyalty, or faith. 

According to the Oxford English Dictionary, the adjective steadfast was first used in English during the Old English period (pre-1150).  The Merriam-Webster Word of the Day  notes that the earliest record of the word appears in late 10th-century texts, specifically The Battle of Maldon, where it described warriors holding their ground.  While the adjective dates to Old English period, the related verb steadfast appeared much later, around 1450, according to the OED.  

Steadfast characters, often referred to as "flat-arc" protagonists, are vital in writing stories because they provide a stable moral compass and anchor the theme, holding true to their core beliefs despite intense pressure to change.  Unlike change-arc protagonists who transform internally, steadfast characters (e.g., Atticus Finch, Katniss Everdeen, Moana) transform their environment, forcing the world around them to adapt to their "truth".

The importance of steadfast characters in writing stories: 
Anchoring the Theme and Truth: 
Embodying the "Truth": Steadfast protagonists usually begin a story with an accurate worldview (the theme). Their journey is not about learning a new lesson, but about proving their existing belief is correct, even when facing significant adversity. 
Serving as a Moral Compass: These characters act as catalysts, forcing other characters—and the audience—to grapple with a specific moral truth. 
Proving the Anti-Theme Wrong: By holding firm, they show that the "lie" or "anti-theme" of the story is inaccurate, strengthening the story’s message. 

Driving Story Structure Through Conflict: 
Challenging the World: While a change protagonist journeys inward, a steadfast protagonist journey is outward. The obstacles they face are designed to test their resolve rather than correct a flaw, making them "problem-solvers". 
The "Lefty" of Storytelling: Because their arcs are reversed, they offer a different, often more inspiring way to structure a narrative where the character changes the world rather than being changed by it. 
"Testing" the Protagonist: The steadfast protagonist must face heavy, often devastating, pressure to abandon their beliefs—the "All is Lost" moment—which makes their ultimate refusal to bend more powerful and heroic. 

Evoking Audience Emotion and Resilience: 
Inspiring Through Resilience: Audiences often admire resilience more than change. A character who perseveres through misery and "holds fast" can be more inspiring than one who simply learns a lesson. 
Evoking "Steadfast Bravery": These characters show "patient doggedness," maintaining their self-worth and beliefs in difficult, long-term dangerous situations (e.g., soldiers,, or those fighting for justice). 
Providing Reassurance: They represent a reliable force in a chaotic world, giving the audience someone to trust throughout the story. 

Creating Dynamic Secondary Characters: 
Influencing Others: While the protagonist is steadfast, their role is often to be the "Influence Character" who brings about change in others. For example, in Moana, Moana is steadfast, while Maui changes his worldview to match hers. 
Highlighting Inaccuracy: By being firm and right, they make the surrounding characters' inaccuracies, flaws, or refusal to change more apparent, which can enhance drama. 

When to use a Steadfast Character: 
Steadfast characters are particularly powerful for stories that focus on: |
External Challenges: Adventures, war, or mysteries where the main goal is overcoming an antagonist (e.g., Sherlock Holmes, James Bond). 
Moral Dilemmas: Stories about maintaining integrity in a corrupt environment (e.g., Atticus Finch in To Kill a Mockingbird).
Inspiring Change: Tales where one person stands up to change a community (e.g., Arrival, Wonder Woman). 

To keep a steadfast character from being boring, writers must ensure they pay a high cost for their beliefs, experience doubt (even if they don't change), and engage in active, hard-won struggles against the plot's obstacles.