In keeping with the post below about writing believable villains, use this bookend prompt to write a short story (or character analysis, or novel) to create a sympathetic villain or villainess. This is good practice for considering your villain as more than a moral opposite to your hero. A good villain does that too, but he or she has an entire existence outside what they do to your main character.
Use the two-part prompt in any order, as long as one of the bookends is at the beginning of your writing, and the other is at the end. Good luck, and have fun writing!
Left Bookend: I told them not to do that. They should have listened to me.
Right Bookend: Someone had to; can I help it if that 'someone' was me?