Once, there was a major villain. They committed every crime one could think of, and did it with a song in their heart and a skip in their step. Then, something happened. The Atoner has realized the error of their ways, possibly wants to make amends, and have decided that they will do so via heroic deeds. Simply going to jail won’t do, because this isn’t always applicable to their “sin.” Besides, they have all these amazing skills from being a villain that would be wasted, and they can do more good out there.