The original series of TMNT comics were inspired by Frank Miller's work, and the tone was relatively dark and serious.
In keeping with the "grim 'n gritty" feel to parody Frank Miller's Ronin/Elektra material, the Turtles engaged in a greater amount of overt violence in the pages of the early Mirage comic book series by Eastman and Laird. As the TMNT were introduced into the mainstream, they were radically redesigned. In issue #19 of Teenage Mutant Ninja Turtles, the creators published an editorial addressing any possible concerns of readers as a result of this. It stated, in part: "We've allowed the wacky side to happen, and enjoy it very much. All the while, though, we've kept the originals very much ours – forty pages of what we enjoy and want to see in our books, whether it comes from our own hands or from those of the talented people we work with." In the film Turtles Forever, the original Mirage Turtles refer to their descendants as "sell-outs", in reference to their colorful accessories (the originals are conveyed in black and white).
The movies and television shows with which I am familiar1 are geared toward children. Have they ever been adapted in a format consistent with their darker, more adult-oriented origin?
1 The original cartoon series, the second cartoon series, the current cartoon series, the first 3 movies, and the most recent movie. I've also read the original comic book series.