It takes a lot to make a superhero. Maybe it's a freak accident of some sort, or maybe it's your birthright, or maybe it's the fact you just got lucky and someone handed you a nice, shiny, green ring but, whatever it is, all the best ones have a dark and tragic past to go hand in hand with their abilities.
Oh sure, there's always room in the superhero pantheons for a happy go lucky, smiley-faced caped crusader, but the best ones - the ones that resonate with readers more often than not - are those that have been through the proverbial wringer on their way to becoming midnight vigilantes.
Perhaps it's because readers find it easier to relate to someone who has as many problems as they do, or perhaps it's because it always feels a little bit good to know someone out there has it worse than you do but - pop psychology aside - most will gravitate towards a hero with a tainted history more readily than one where butter wouldn't melt.
It's not always those heroes who wear their darkness on their sleeves who have the most tortured pasts either, and that's what makes it all so interesting...