I've read a few followup books recently- Mistborn after reading Elantris by Brandon Sanderson and Gathering Blue after reading several books by Lois Lowry over the years, including The Giver.
The characters, the magic system, the goals of each, the societal structure were all different, but because of the similarities, I was immediately comfortable.
Same idea with Gathering Blue. A child is stuck in a comunity that is unfair. That could describe The Giver, too. The conflicts are a little different, the plot and details differ, but the voice is the same.
To be a successful writer, a person has to sell books. And that means readers picking up/clicking on your book and paying for it. It's a lot easier to keep a customer than to find a new one. I think this is why writers are encouraged to find a genre they love and stay put!
I think you can switch things up quite a bit, and still have a followup book that feels familiar. I'm pondering POV for my second novel- is it neccesary to write again in first person? Would a switch from first to third cause me to lose readers that love the intimacy of first person? I'm not sure.
Brandon Sanderson does have a midgrade book out, 'Alcatraz Versus the Evil Librarians'. We haven't picked it up yet. In fact, I hadn't realized he had written anything but adult fantasy until writing this post. The point being, nobody has to swear off writing for other audiences, but you might want to establish yourself firmly in one, develop a fanbase, and then branch out.
One thing I don't like is when an author switches genres and there's nothing on the cover that tells me that this new book is going to be quasi erotica. I can look at the 'Alcatraz' cover and know immediately it's written for kids. Or a certain book my son was reading yesterday. We'd read another book by that author and so I assumed it was fine. But he said he didn't think he should be reading it because it had some bad words in it, and I asked him, "What words?" and he told me, and I agreed that I'd rather he not read it. Then he chastised ME for telling him to read it! This cover looks midgrade to me, but is actually YA.
We're reading another of MT Anderson's books right now- a midgrade novel-
'Jasper Dash and the Flame-pits of Delaware' and love it.
Anybody have any thoughts on this? How much can you vary and still build a fanbase, theoretically?