"Resolve" originated in the late 14th century from the Latin resolvere, meaning "to loosen, unyoke, undo, or explain".  It combines re- (meaning "again" or indicating a backward motion) with solvere ("to loosen, release").  The word originally meant to melt, dissolve, or separate into component parts, later evolving to mean firm decision-making.  It moved into Middle English as the verb resolven, meaning the literal, physical act of loosening, dissolving, or breaking something down (e.g., melting solid into liquid).  The meaning of the word then evolved as follows: 14th-15th Century: Melting, dissolving, or separating.  16th Century: To reduce to simple notions, explain, or analyze.  The noun "resolve" (firmness of purpose) arose in the late 16th century. 17th Century: To make a firm decision (a figurative "loosening" of doubt or reaching a conclusion).  

According to the Oxford English Dictionary (OED), the verb resolve was first used in English during the Middle English Period (1150—1500).  The OED records the earliest known usage as occurring before 1398 and appears in the works of John Trevisa (a Middle English translator).   Its its earliest usage, it meant to melt, dissolve, or separate into component parts.  The noun resolve (meaning a firm determination) appeared much later, with the OED citing its earliest evidence from 1592, in a translation by Anthony Munday.  The earliest known use of the adjective resolved is during the Middle English period, with evidence dating back to 1497.   It is classified as a past-participle adjective originating from the verb "resolve," frequently used to mean determined, resolute, or firm.  

A character's resolve—their unwavering determination to achieve a goal despite obstacles—is the engine that drives a story's plot, creates necessary tension, and secures reader engagement.  It transforms a passive protagonist into an active one, ensuring that the character's desires, rather than mere coincidence, shape the narrative. 

The importance of character resolve based on key storytelling principles: 
Drives the Plot and Action: 
Creates Narrative Momentum: A strong desire (resolve) forces characters to act, moving the story forward, rather than waiting for things to happen to them. 
Defines the Conflict: Resolve dictates how a character interacts with external obstacles and internal dilemmas, driving the conflict that keeps readers turning pages. 
Forces Necessary Change: When a character is forced to choose between their goals and their comfort, their resolve to push forward generates the necessary "suffering" that makes a story interesting and transformative. 

Increases Emotional Involvement and Stakes: 
Relatability: Readers empathize with characters who are tested and must display resilience, mirroring the complexity of human life. 
Raises the Stakes: A character’s deep resolve to achieve something makes the obstacles to that goal seem more dangerous and significant to the reader. 
Showcases Growth: By pushing through failures and obstacles, a character’s resolve defines their true nature and triggers personal development and growth. 

Provides Structure and Unity: 
Thematizes the Narrative: The story's theme (or "guiding truth") is often upheld by the character’s steadfastness in their convictions. 
Prevents "Flat" Stories: A lack of resolve makes a story feel "flat," boring, or lacking in impact. 
Defines the Ending: A character’s resolve to win (or sometimes, their failure to remain resolute) leads to the climax, allowing for a satisfying, earned resolution. 

Distinguishes Character Roles: 
Protagonist vs. Antagonist: A protagonist is defined by their resolve to reach a goal, while the antagonist is defined by their own, often opposing, resolve, creating dramatic tension. 
Steadfast Characters: Sometimes, a character’s impact rests on their refusal to change their mind, acting as a "stoically static" moral compass, such as Atticus Finch in To Kill a Mockingbird. 

A character's resolve makes a story "unputdownable" by transforming a series of events into a meaningful, personal journey that engages the reader emotionally.