Character Writing: Redemption Arcs

One of the most effective and beloved ways to develop characters in storytelling comes in the form of the redemption arc. Suddenly, a switch gets flipped in an antagonist's mind, bringing them over to the side of the good guys just in the nick of time. Audiences eat it up every time, so much so that many people claim the redeemed character as their favorite. But why does the redemption arc resonate so well with people, and what are the best ways to include it in your work of fiction?