Superheroes and supervillains usually have origin stories specifically created and stated. I do wonder if it's necessary though. At least, does it need to be told right away? I've seen it successfully done both ways, and I don't really have a preference. But, I was watching the Star Wars prequels again, and I found myself wondering if the origins of Darth Vader really needed explaining? I struggle with the same question in my own stories as well.
I think back on some of my favorite villains and am surprised to discover that most indeed don't have a backstory explaining why they turned to evil. They simply are, and the story works fine without those added details. Actually, I think the extra baggage of history works against a villain and makes them sympathetic (unless that's your goal in the first place). It's difficult for an audience to hate what they know intimately. Then again, you have the newest Avengers movie where you witness the birth of Ultron and yet he is still completely despicable--though it doesn't hurt that he's a pitiless robot.
The funny thing is audiences still want to know. It's up to the storyteller to decide if that knowledge should be revealed. It's a tough choice. Actually, knowing what to show and what not to is probably the hardest part of storytelling. The author has lots of choices to make, and I doubt anyone ever makes every one of them perfectly. As usual, we do the best we can and hope for a miracle.
If all goes well, a story is born unto the world, in all its wonderful splendor and glory.
- M