Big characters have big problems.
If you work on a well-established character that has years of publishing (or perhaps cinematic) history you are faced with important challenges. If you ignore these problems, I can pretty well guarantee that you will either choke or write yet another generic story that will not do you, your editor, or anyone who reads it much good.
So, herewith, are what I consider the biggest of these challenges:-
* You must respect the character's history (and the fanbase).
* You must bring your own voice and talents to the job.
* You must do something different with the character to what has been done before, even if it's minor.
* You must identify the essential aspects of the character (and beware - they are not necessarily the characteristics the marketing people will tell you are essential) and then absolutely adhere to them.
Now, notice how these notions are seemingly at odds? There's a definite tension between them.
That tension is where gold may be discovered. When you figure out how to, for example, tell a Batman story that's fresh and original and yet shocking and yet so right (and most of all an enjoyable read); that's called The Dark Knight Returns, and to a lesser-talked-about extent any Alan Grant-scribed Batman comic. When you go through the motions and invest the work with nothing genuine or new, that yields poor results (like, ummn, DK2?).
It's not easy. It's about having a process to use in working out 'How far can I go?' and 'How do I tell when I've gone too far?' and 'when have I played it too safe?'.
In Sherlock Holmes stories I wrote that appear in the collections 'Sherlock Holmes: The Game's Afoot' and 'Gaslight Grimoires' I wrestled with these questions, within the ambit my editors gave me in each case. I found there were things that I didn't want to do but for the stories to suceed I had to do. So, to get my balance back I asked myself why the ideas I was tempted to use didn't sit right with me, why they intimidated me. This internal dialogue often resolved the question and allowed me to make to final choices.
Asking a question of oneself, especially an unspeakable question, is often revelatory in itself.
If all that fails, show what you've written to your mates (the ones that know how to write professionally) and they'll tell you when you stink.
CS