Atonement was a huge theme in Buffy the Vampire Slayer
because being able to make mistakes and learn from them was part of growing up. The supernatural drama that used the forces of darkness as metaphors for the horrors of adolescence made the traits that formed heroes and villains mercurial, and therefore authentic to real life. Often the characters like Angel, who committed some of the most depraved acts of violence, were capable of profound sacrifice, while some of the characters like Willow, who pledged themselves to do only good, had the capacity to generate unspeakable chaos.
Related: Buffy the Vampire Slayer
: 10 Times The Show Tackled Deep Issues
The line between what made a character good or bad was nebulous, which made not only for compelling television, but introduced the opportunity for anyone's redemption. Sometimes characters had moments of redemption, and sometimes their development seemed like one long redemption arc stretched over seven seasons.