Originally posted by Bingowings:

"...you could construct a moment of realisation during the Grevious/Obi Wan duel by dubbing a new line in, adding an eye close up and maybe a very brief flashback and Bingo!"

That's too much plot development to cram into RotS, plus it doesn't do justice to the relationship between the two characters. If someone did try to do Maul-Grievous I'd like it to be something that unfolds over the course of the PT. Something along the lines of: Maul and Kenobi meet in TPM, Grievous is then introduced in AotC hell-bent on getting revenge against Kenobi, and then the rivalry is finally ended in RotS.

You know how most television dramas have an "A" story and a "B" story. The Grievous/Kenobi rivalry could be the "B" story of the PT while the Anakin Skywalker plot would be the "A" story.