A structural catalogue of non-player character types found across interactive fiction, RPGs, and game narratives. Organized by function rather than genre. Each entry describes what the NPC type does within the system—what role it serves, what behavior it exhibits, what relationship it establishes with the player. Comparable in intent to Propp's morphology of the folktale, but for the dramatis personae of playable worlds.
The most fundamental classification: what does this character do for the player? These types are defined by their narrative and mechanical function—the job they perform in the system. A single NPC can serve multiple functions, and many games disguise one function inside the skin of another.
The character who assigns a task. "Go to the cave. Retrieve the amulet. Return to me." The quest giver converts open-world possibility into directed action. Without them, the player has freedom but no purpose. The mechanism is transactional: the quest giver offers a problem, and implicitly or explicitly promises a reward. Variations include the reluctant quest giver (must be persuaded to reveal the task), the deceptive quest giver (the real task is not what was described), and the absent quest giver (a letter, a recording, a dying message—the giver is gone but the task remains).
EXAMPLE: The village elder says: "Wolves have been taking our sheep. Find their den and deal with them." THE PLAYER NOW HAS A DESTINATION, A GOAL, AND AN IMPLIED REWARD—ALL FROM ONE LINE OF DIALOGUE
The character who converts resources into capability. Buy a sword, sell a gem, trade pelts for potions. The merchant exists at the intersection of the game's economy and its power curve. They determine what the player can become by controlling what is available for purchase. A merchant's inventory is a design statement: it tells the player what the designer thinks they'll need. The traveling merchant (appears unpredictably, carries rare stock) and the black-market dealer (sells forbidden items at premium prices) are common variants that add timing pressure or moral texture.
EXAMPLE: "Welcome, traveler. I have swords, shields, and potions. What'll it be?" THE MERCHANT'S INVENTORY TELLS THE PLAYER THAT COMBAT AND SURVIVAL ARE IMMINENT
The character who blocks passage until a condition is met. "None may pass without the king's seal." The gate guard is a lock in human form. They transform a mechanical barrier (you need item X) into a social encounter (you must deal with person Y). The guard may be bribed, persuaded, intimidated, tricked, or fought—each option reflecting a different verb the game supports. The gate guard's personality determines which verbs feel appropriate. A sympathetic guard invites persuasion; a corrupt one invites bribery; a hostile one invites force.
EXAMPLE: "The bridge is closed by order of the magistrate. You'll need a writ of passage." THE PLAYER MUST NOW FIND THE WRIT, FIND THE MAGISTRATE, OR FIND ANOTHER WAY ACROSS
The character who provides information the player cannot obtain elsewhere. Lore, prophecy, warnings, map data, hints about puzzles. The oracle converts the player's ignorance into knowledge, but often at a cost or in a cryptic form. The mechanism's tension lies in trust: is the oracle reliable? Oracles who speak plainly are tutorials in disguise. Oracles who speak in riddles are puzzles in disguise. The unreliable oracle—who mixes truth with falsehood—is the most interesting variant, because the player must cross-reference their claims against other evidence.
EXAMPLE: "Three keys open the vault. One lies with the dead. One lies with the living. One lies." THE THIRD SENTENCE IS A WARNING ABOUT A FAKE KEY—IF THE PLAYER CATCHES THE DOUBLE MEANING
The character who travels with the player. Companions occupy a unique structural position: they are both NPC and quasi-extension of the player. They may fight, carry items, provide commentary, react to decisions, or offer abilities the player lacks. The companion's deepest function is witness—they make the player's journey feel observed and therefore real. A game played alone in empty corridors feels different from the same game played with a companion who remarks on what you do. Companions who approve or disapprove of player choices become moral mirrors.
EXAMPLE: After the player steals from a merchant: "I saw what you did. I won't say anything... this time." THE COMPANION'S REACTION GIVES THE THEFT MORAL WEIGHT IT WOULD NOT HAVE HAD IN A SOLO GAME
The character who pursues the same goal as the player but in competition. The rival provides urgency without being a direct antagonist—they don't want to destroy the player, they want to beat them. Rivals create time pressure (if you don't act, they'll get there first) and force the player to evaluate their own competence against a visible benchmark. The rival who is friendly creates a different texture than one who is hostile. In either case, the rival's progress is a clock the player cannot pause.
EXAMPLE: You arrive at the tomb entrance. Fresh bootprints lead inside. Someone got here first. THE RIVAL'S PRESENCE IS FELT THROUGH EVIDENCE RATHER THAN DIRECT ENCOUNTER
The character who appears to fill one role—ally, companion, quest giver—but is secretly working against the player. The betrayer's function is structural reversal: they exist to destroy trust in a category the player had relied on. After a companion betrays you, every future companion is suspect. The betrayer works only if the player believed the disguise, which means the designer must invest in making the character seem genuine before the turn. The longer the deception holds, the more powerful the revelation. A betrayer revealed in the first act is a plot twist; one revealed in the third is a tragedy.
EXAMPLE: Your guide leads you confidently through the swamp—directly into an ambush she arranged. EVERY HELPFUL THING SHE DID EARLIER NOW READS AS MANIPULATION IN RETROSPECT
Answers to examples are in invisible ink after each entry (highlight to reveal)
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