[[quoteright:216:[[Franchise/{{Halloween}} http://static.tvtropes.org/pmwiki/pub/images/aaalaurieaaa_4881.jpg]]]]
[[caption-width-right:216: From DamselInDistress to ActionGirl. [[Film/{{Halloween 1978}} A lot can change]] in [[Film/HalloweenH20TwentyYearsLater twenty years]].]]

->''"You have the opportunity, here and now, to choose. To become something greater and nobler, and more difficult than what you were before. The universe does not offer such chances often, G'kar."''
-->-- '''Nameless Narn''', ''Series/BabylonFive -- "Dust to Dust"''

Character development is, by definition, the change in characterization of a DynamicCharacter, who changes over the course of a narrative. At its core, it shows a character changing. Most narrative fiction in any media will feature some display of this.

While the definition of "good" and "bad" character development is subjective, it's generally agreed upon that good character development is believable and rounds out a well-written character. Bad character development leads to the feeling that someone is manipulating the events to their own whims, or even reduces the character's believability.

There are many sub-tropes that take place due to this trope, some of which include

* The ComingOfAgeStory is centered around this trope in the context of growing up.
* DarkerAndEdgier and LighterAndSofter can either deepen a character or round out unnecessary roughness. They can also turn them into a pile of mush or make them an unsympathetic jerk.
* Similiarly, despite the negative connotations in the name, BadassDecay can soften a previously harsh character. [[TropesAreTools Or it can ruin an awesome character.]]
* {{Flanderization}} is when a character has a quirk or personality trait that slowly becomes their only defining characteristic.
* The HeelFaceTurn, FaceHeelTurn and MoralityAdjustment tropes rely on [[SortingAlgorithmOfFaceHeelTurning character development]] to make this a believable turn of events.
* HiddenDepths has a character develop in unexpected directions. It can also describe FlatCharacter turning into a RoundedCharacter.
* OutOfCharacterMoment may be a positive or negative example, generally steering a character in new directions without wholesale CharacterDerailment.
* A CharacterCheck can help steer a character who developed too far from their original character back into being themselves, or remind the audience that they still are the same person they used to be no matter how much they've changed.

These are hardly the only examples. The EvilTwin of CharacterDevelopment is CharacterDerailment. Beware this trope. To see the opposite of this trope, see StaticCharacter. See also FlatCharacter and RoundedCharacter. Compare HiddenDepths, where something is revealed that was true all along, but would not have been visible before.

The oldest form of this is [[ProtagonistJourneyToVillain the moral decay]] of the AntiHero, as in Shakespeare's ''Theatre/{{Macbeth}}'' or ''Coriolanus'', or the modern equivalent of [[Characters/BreakingBadWalterWhite Walter White]] in ''Series/BreakingBad''. In each case the protagonist's growing vices are timidly concealed at first but then openly displayed. A fascinating reversal of this occurs in ''SchindlersList'' - at first Schindler claims he is only saving people because he needs them for his business. By the end he is openly losing millions. His inversion of moral decay goes from an intention to get rich by exploiting slave labor, to grieving over not saving one more person.

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