My main characters vary depending on my story and the age level I'm aiming at. A 10 year girl testing out a new planet for the first time has a very different voice from a 30 year old man working on a cattle ranch. If not, I'm doing something wrong! :)
But my voice stays kind of the same throughout. I use the same mix of long and short sentences. I adore sentence fragments and they show up everywhere. I have a lot of short paragraphs - often one liners - no matter what genre I'm writing. None of my paragraphs go on for very long.
My sense of humour stays the same and probably shows up in the same way. I'm not a huge fan of reading or writing description, so that's going to be consistent as well.
There are changes with each story of course, because the main characters have a lot to say in the story, but I think my voice remains more or less the same.
And I'm okay with that. Will I ever get to this point?
Probably not, but I'd like to!
What about you, does your voice change with your stories, or does it remain the same no matter what you're writing?