I'm still "between books". I've been playing around with "Scorpion 2", but it's still in the teeth-pulling stage. It's moving slowly, 3090-800 words at a time, and some days not at all. I'm writing, kind of, or at least going through the motions, adding words to other words on the page.
Does it grab me and refuse to let go? Not really. Not yet. It needs a lot of faith and momentum to get there. And it's hard to muster the faith if you don't know what shape it is taking. IF it will take a shape. With every book, that's a big bet of dozen of hours of work. Much of the stuff ends up unfinished and with hundreds of hours of work wasted.
My brain is incubating a new, fresh idea, unconnected to anything else. I think I'll let the muse play with that, before I finish the other projects. Right now, it's more important than ever to find that passion and energy. And that's what I keep telling other writers: to follow the energy.
So, I'll start on this pretty soon. These slow periods are times when I plan and plot and think, and do otherwise very little.