The comic and illustration, as many other artistic disciplines, have an inevitably comercial purpose, it means that could be seen an evolution as painting or contemporany art, but more controlled. We have several examples in some comic authors that experimenting with their own style, have got an impresionism or expresionism way in their comics or graphic novels, but they are only a few.
But in the cases of Bill Sienkiewicz and Frank Miller, united some times by the same characters and interests, that evolution could be held by a well working enterprise as it is the american comic and, even more surprising, that has happened with carachters who have hundreds of volumes, done with an academic style, what could be said in a traditional way, followers of the great Marvel names as Buscema.
The miller’s evolution, which comes from a detailed style to a focus on the scripts, with a shadow based drawings, make that, from The return of dark knight have a greatest personality and fluency, all that makes the Miller’s work so personal and easily recognizable.
A similar thing happens, but so more surprisingly, to Bill Sienkiewicz, classical drawer and correct to the limit, he began to stand out for his evolution to the craziest loosenest on his covers and New Mutants comics, that evolution origins a surprising style and opposite to his past stage that, as happens with Miller, is difficult to relate his classic drawings to the next works they have done.
Even more than evolution, we could speak about reborning, something that for the experienced eye, almost for Miller, could be expectable.