Tom Batiuk's Funky Winkerbean debuted in 1972. It focused primarily on the cast in and around Westview High School, mostly the students but also the parents and teachers. It provided more-or-less typical humor that you might find in a newspaper comic strip in the 1970s and '80s. Here's an example of the type of humor he frequently used...
Batiuk did the strip in that manner for twenty years. In 1992, he was undergoing some contract negotiations and was able to convince his syndicate that he wanted to radically change directions. He jumped forward about five years in the characters' lives, and started aging them in real time. (As opposed to the perpetual agelessness he had utilized previously.) He also largely dropped the comedy and made the strip more of a drama, addressing various social issues. This culminated in "Lisa's Story" in which one of his primary characters contracted breast cancer, fought the illness for nearly a decade, but eventually died in 2007.
Batiuk revamped the strip again, jumping forward another ten years in the characters' lives. Even the occasional bouts of light-hearted comedy were dropped entirely, and the strip has been focused squarely on drama with aging catching up to the characters and death becoming a recurring theme. Josh Fruhlinger of the Comics Curmudgeon has gone so far as to say, "Funky Winkerbean is a black hole of bleakness and depression and cancer from which no joy or laughter can escape" and the strip is not infrequently mocked by others in a similar manner.
So what happened?
The problem isn't so much that Batiuk talks about death or killed off several of his characters. That happens in comics. The problem is that Batiuk betrayed his brand.
See, Batiuk spent twenty years establishing Funky Winkerbean with a very specific voice. Two decades building up an expectation of what readers would see when they read his strip. That's what a brand is. It's a promise you make with your audience. The tag lines and logos and all that are indicative of that promise, but it's really the promise that's most important.
That's why people reacted so badly to New Coke. It wasn't so much that New Coke tasted bad; it's just that it broke the promise Coke had been making for generations. When you drink Coca-Cola, it tastes exactly like this, whether you get it from a can or a bottle or a fountain machine, whether you're in the United State, Mexico, Japan, the Netherlands, or South Africa. Coke is Coke is Coke. That was what they promised. When they suddenly stopped fulfilling that promise (Coke was no longer available and the New Coke substitute tasted notably different) that's why people got angry.
Funky Winkerbean is the same way. People had decades of Batiuk showing them a strip that looked like the one above. Now, he was suddenly doing something very different. Something very much not like what he had done before, despite calling it the same thing. Funky Winkerbean was no longer funky in any way, shape or form.
You want to know how damaging that was to his reputation? He's still getting shit over that change... despite the fact that he's now spent more time working on dramatic strips than he did on comedy. That shift was 22 years ago!
My point is that, whether you're deliberately working on it or not, you are creating a brand with your body of work. Whether that's a webcomic or a series of graphic novels or a blog or whatever, people will come to associate your name with a promise. When you read my work, you expect something whether you're actively conscious of that or not. And if that expectation is radically different than the reality, then that's a broken promise and could have a significant impact on your brand.