For example: in the story Star Wars, you have the story Darth Vader. In the second movie, a plot twist reveals Darth Vader as Lukes father. At the end of third, he then undergoes _ where he kills the emperor and saves Luke. What is blank? I believe the term is redemption, but is there a different literary term?
If a character makes up for past bad actions by some outstanding effort, redemption, "the act of redeeming" or "salvation from sin" probably is among the most suitable terms. Repentance, "A feeling of regret or remorse for doing wrong or sinning" is a related term.
Absolution, suggested by Irene, is of similar tone: "An absolving, or setting free from guilt, sin, or penalty; forgiveness of an offense", but of course involves another agent, while one can repent or redeem oneself without aid.
Even within fiction, thoroughgoing changes such as redemption or absolution of a bad person may be hard to believe. To avoid implausibility, authors usually settle for lesser breakthroughs among their characters. A character may have an epiphany, "An illuminating realization or discovery, often resulting in a personal feeling of elation, awe, or wonder" during a story's dénouement. The Characterization article in wikipedia notes:
On the same topic, wikipedia comments:
In short, some of the relevant literary terms are epiphany, falling action, dénouement, and catharsis.
The verb form for redemption is pretty straightforrwad. Instead of
it should rather be