Well, I've revealed that she's the immortal Cassandra (from Highlander, also played by Tracy Scoggins) in Nine Lives, which I will eventually complete - there's no reason why she shouldn't later assume the identity of Elizabeth Lochley if she doesn't get killed some time in the intervening centuries.
Marcus L. Rowland Forgotten Futures, The Scientific Romance Role Playing Game
I've actually done a bit of this in A New Hero. I made Cat Grant a woman who came from an abusive relationship. She has a son. She is embarrassed about her past. She has gotten her act together and has even won a Kerth. Heck, I even had her second marriage be to editor-in-chief of the Daily Planet, Jim Olsen. I have a little unfinished fic sitting on my hard drive about how they came to be a couple.
I've suggested that Cat lets out her inner exhibitionist earlier and ends up married to Arthur Chow. When someone (Lex) tries to kill Chow and take over his business illegally she goes to Lois and Clark for help investigating.