In-Universe Catharsis

In Real Life, a big part of why we love Media is that it is cathartic. It is fun to blow off steam shooting up Mooks, crying over a Tear Jerker, enjoying a Sadist Show, etc. When a story does this for a reader in the real world, it's a Subjective Trope. When it occurs In-Universe, it's less subjective.

This In-Universe Catharsis often takes a more serious form, where psychological ills are healed through ceremony or painful experiences. Basically, usually as a major plot point, a character either seeks or inadverdently goes through an experience that normally only a Nightmare Fetishist might seek, and it helps them deal with a medical, psychological, or other condition.

Anime and Manga

 * In Karin, gloomy Fumio becomes an energetic optimist after being bitten by Karin.

Film

 * The Horse Whisperer ends up helping both the horse and owner this way.
 * In Analyze This, Robert De Niro shooting the couch probably counts, as it was likely extremely cathartic for his character.

Literature

 * In Kushiels Dart, Phedre goes to the temple of Kushiel to atone for her role in the death of her master and the things she had to do when a captive of the Skaldi. Kushiel himself is said to be the patron of a very harsh mercy, attended by masked priests and priestesses who inflict painful rituals on those who come seeking atonement.
 * Aaron Allston's X-Wing novels in the Star Wars Expanded Universe are full of this. Most notably, Myn Donos' arc in Wraith Squadron contains at least two distinct and separate examples of this trope.

Live-Action TV
""By G'Quan, I can't recall the last time I was in a fight like that! No moral ambiguity, no hopeless battle against ancient and overwhelming forces! They were the bad guys, as you say, and we were the good guys. And they made a very satisfying thump when they hit the floor."'"
 * The Star Trek franchise has touched on overcoming psychological issues through cathartic experiences on multiple occasions.
 * In Star Trek V: The Final Frontier, Sybok uses his unique empathic ability to share and help conquer a person's greatest emotional trauma to gain the trust of most of the crew.
 * One of the biggest reasons fans never liked Dr. Pulaski was how much she rudely insulted Data. Not that it's an excuse, but she did so because she knew that no matter how much she did so, Data would never become angry or offended, seeing as he cannot experience emotions. In a sense, she was using him to relieve stress.
 * Babylon 5:
 * In one episode, a mentally disturbed veteran of the Earth-Minbari war reenacts Arthurian legend with Delenn as a means of finding peace.
 * Earlier in the same episode, the same veteran gets in a fight with some Downbelow thugs, and gets helped out by G'Kar, who recounts how it felt shortly afterwards:


 * In another episode, Marcus Cole has just finished beating a room full of thugs senseless in a brawl.

"Marcus Cole: Well, they said I was carrying around a lot of repressed anger. Lennier: And? Marcus Cole: I'm not repressed anymore!"


 * The Dark Truth on Eli Stone can be used for this, if this troper remembers correctly. However, it's usually used for other things.

Oral Tradition, Folklore, Myths and Legends

 * Older Than Feudalism; in Norse Mythology, after his mother's blessings seemed to make Baldur invulnerable to any form of harm, the other gods would make a game out of throwing things at him - rocks, sticks, spears, even arrows. Subverted ultimately, however, as this turned deadly: unfortunately, Loki discovered one object that was not covered by the blessing, and tricked the blind god Hoder into shooting Baldur with an arrow made of mistletoe.

Video Games

 * Mass Effect 2: Jack is not what you would call a well adjusted individual, owing in no small part to the horrific experiments performed on her. The mission to secure her loyalty has you guiding her through the abandoned facility where these experiments were performed and dealing with some of the remnants of her past, before setting a Big Bulky Bomb in her old cell and blowing the lab to smithereens. Afterwards, she becomes... well, slightly less Ax Crazy. The achievement you get for completing the mission is even called "Catharsis".
 * Also, after taking down the Shadow Broker and saving Feron, Liara is much more like the person she was in the first game.
 * Max's monologue in the normal ending of Max Payne 2 (concluding with "I had a dream of my wife. She was dead. But it was all right.") suggested that Max underwent a catharsis after, finally breaking away from the self-destructive path that Michelle and Alex's deaths put him onto. Part three says otherwise.
 * At the beginning of Ace Combat 5 The Unsung War, Nagase is saved from a very embarrassing defeat by Captain Bartlett Taking the Bullet for her. The guilt over this accident follows her throughout the game until the mission "Ice Cage" when she finally completes her almost two months-long crash (while looking for POW Bartlett, no less). She is significantly less troubled after she is rescued, even though Bartlett isn't found.

Western Animation
"Bennigan: Uhm... I'm not a proponent of violence, but that was irrefutably cathartic."
 * The Star Trek: Lower Decks episode "Crisis Point" is all about this. Mariner is angry at her mother for sending her to therapy, so she programs the Holo-Deck into a scenario where she can have her idea of therapy, an entire movie where she and the other Lower Decks can play as Space Pirates, brutally murdering the crew of the Cerritos. Ironically, the "movie" ends with her evil alter-ego losing, fighting a holo-replica of herself, leading her to conclude that the therapy sessions are better.
 * The Justice League episode "Twilight (Part 1)", where Darkseid finally gets angry enough at Dassaad to kill him, something most fans would not only hold against him, but say he should have done years ago.
 * In the first episode of Little Demon, Chrissy is in a stall in the lady's room when two bullies drag Bennigan (a student she just befriended) into the room with the intent to beat him up; Chrissy's demonic powers manifest for the first time, and the two bullies are blown to Ludicrous Gibs, getting blood and gore all over Bennigan. His reaction?

Real Life

 * The dictionary definition is here and here.
 * The Other Wiki defines it here, mentioning that some modern psychiatrists call this closure.
 * A number of ancient societies had some form of ceremony that was intended for this purpose.