Flanderization

Flanderization is the gradual reduction of a recurring character, across a long-running series, into a caricature of a single trait that was originally just one part of a fuller personality.

The term comes from TV Tropes, the fan-run wiki of narrative devices — not from academic criticism and not from the show's own writers — and names itself after its example: Ned Flanders, a supporting character on a long-running animated sitcom, whose mild religious devotion in early seasons hardened over hundreds of episodes into his entire personality, with everything else dropped. The word outlasted that origin because the pattern is common enough to need a name independent of any one show.

Three pressures drive it. Writer turnover means later writers inherit a character as a set of jokes that worked rather than as a coherent person, and the jokes that worked are, almost by definition, the exaggerated ones — later hands reproduce the surface trait without access to whatever originally generated it, the same gap Cargo Cult names elsewhere. Audience response reinforces the narrowing: a legible trait gets a reaction a subtle one doesn't, and a series that runs for years optimises toward whatever visibly lands, keeping what worked in a small Survivorship Bias of its own jokes. And the economics of a long run reward whatever is cheapest to write correctly at volume; a single loud trait is easy to hit consistently across hundreds of episodes and dozens of writers, and a full character is not.

The result is best read as Prototype Theory applied to a fictional person instead of a category: a character becomes their own most typical, most cited instance, and the atypical traits that made them a person rather than a type get pruned for resembling the prototype too loosely — a slower cousin of the drift Documentation Rot names in a different domain.