Back when I was working on the original Kitchen Sink run of Megaton Man, I was called upon to contribute to Eclipse Comics' series Mr. Monster, a superhero monster fighter. I've never quite gotten the history of this character to make sense in my mind, but writer-artist Michael T. Gilbert did not create Doc Stearn; he only perpetuated it. (Feel free to Wikipedia and see if you can figure it out.)
To further complicate things, the Eclipse series was highlighted more by the contributions of Alan Moore, Dave Stevens, Bill Loebs...and pretty far down the list, me. Exactly what MTG did--aside from function as a wise old editor in the Will Eisner mold--and make some really arbitrary alterations here and there that, in my view, did not improve the work. But then, I don't entirely recall how we worked--whether it was from a script, layouts, or what.
I do recall Eclipse editor Cat Yronwode intervening at one point--she was angry at me because MTG hadn't kept her apprised of who he was collaborating with. In particular, she didn't care for how I inked the babe's hair on the cover to #6--she thought I had used a pen, when in fact I had used a brush. The whole assignment was really strange. The same went for #10, in which I was called upon to draw the 3D segments--again, with arbitrary alterations made by MTG after the fact. I guess he felt the need to change a few heads and figures to maintain consistency with his readers, but I thought his patches were sloppy and hardly an improvement. Oh, well. It was his book; I had my own thing to worry about.
The main thing is that fans enjoyed the end result, and nearly every convention I appear at, at least one or two fans bring Mr. Monster #6 and #10 up to me to autograph, and I'm proud to have been a part of it. I've also done Mr. Monster commissions--don't tell MTG--for art collectors. And what would comics be without convoluted character histories and production processes that make mincemeat of the auteur theory? Enjoy!