^ Interesting take.
After hearing about what Paul Dini did with the character in Detective Comics as well as rumors that he may be used in a similar capacity in TDK, I decided to revise my Riddler.
Edward Nashton is a private investigator in Gotham. He always loves a good mystery and prides himself in solving the cases. The problem is that he's not reaching the fame he wants to achieve. And the cases he's given are too easy.
When the Batman hits Gotham, Nashton becomes fascinated by the Batman, who is solving cases that the police didn't and is gaining fame for it around Gotham.
Inspired, Nashton decides to step up his business and get more theatrical. Why not since people are turning towards a man in a batsuit to fight crime in Gotham?
So he changes his name to Edward Nigma and renames his detective agency E.Nigma Investigations. He solves some cases well and gets noticed because of the catchy name. His fame grows. The press start to hound him and Nigma loves it.
When he and Batman end up working on the same case of a serial killer, Nigma tries to get Batman to accept him as an ally so that they can solve the case together and not have to worry about "who's going to look bad when one of us solves it first." But Batman refuses. He doesn't like Nigma and thinks that the investigator treats every mystery like a game without any regard for whose lives are at stake.
Nigma is disappointed by this rejection, but decides that this is even more motivation for him to solve the case first.
And he does. Or so he thinks because Batman proves him wrong.
Nigma becomes the laughing stock in Gotham. E.Nigma Investigations loses its clients.
Nigma, enraged that he has been outsmarted in public, develops a new obsession with Batman. Now his dream is to become famous for outsmarting and defeating the Batman once and for all. I suppose this incorporates the "revenge origin" that has been in the cartoons and Batman Forever.
So he develops a secret identity: The Riddler.
The bright green outfit and purple mask would distract enough people who happen to see him from knowing that Nigma is actually the Riddler.
Soon, The Riddler publishes his riddles as a challenge to Batman and the police force. The public is curious who will stop this madman committing crimes that coincide with riddles.
As Nigma, he pretends that he, too, will investigate "the Riddler crimes."
The plan? He's going to cheat the game.
Edward Nigma is going to beat Batman in solving the case of The Riddler...because Nigma is the Riddler.
Or so he thinks. Because Batman defeats him yet again and exposes Nigma as the Riddler. E.Nigma Investigations closes for good and Nigma lands in Arkham.
From then on out, the Riddler will not rest until he's had his revenge on Batman in outsmarting him.