So Bob is constantly angry. Maybe he has a bunch of Berserk Buttons. Or maybe he has a Hair-Trigger Temper. Perhaps he's prone to Hulking Out and going into a frenzy. Sooner or later his friends get fed up with his temper. Or maybe Bob decides to learn to control his Temper on his own. Either way, he'll do whatever it takes to become a calmer or more peaceful person.
This Trope usually goes hand in hand with a Heel–Face Turn for villains, Anti Villains, and even Anti-Heroes, although the last one depends on how dark they really are.
There are many ways they can go about achieving this inner peace. One of the most prominent ways is Walking the Earth. The character leaves on a journey to learn more about themselves, the world, and their place within the world. This often involves leaving behind their possessions as well.
If the villain is the one who tames his anger, it may be because there's a bigger threat coming. The villain will put their hatred on hold until their common enemy is defeated.
A common trope in martial arts series. A new disciple will become the pupil of an Old Master or The Mentor. The disciple will go from being a loud-mouthed kid or an Arrogant Kung-Fu Guy to a Martial Pacifist.
This Trope is Older Than Dirt. In Classical Mythology after killing his music teacher accidentally, Hercules is sent to a farm to become a more peaceful person. Another old example is Moses from The Bible. After finding out that he was a Hebrew, Moses kills an Egyptian Slavemaster who's beating his slave and flees to Midian. While there, he gets married and becomes a wiser and more peaceful person.
Contrast Teach Him Anger, where a Nice Guy or an Extreme Doormat is given a backbone.
In a comedy, this often leads to We Want Our Jerk Back! because Status Quo Is God.
