Who lives wise enough will see the past and present collapsing into a single dimension and understand that who you are leaves a print in the world. A memory of your flaws. A ghost of yourself.
And some people keep the ghosts alive. Because it is the only witness left. A proof of what happened. One harms without permission, and the other might reflect the evil back forever.

What one had done is permanent. Who you were is inescapable.