It's an interesting middle ground to stand on, honestly. It's not quite like having a series, where you know the next book you'll be writing is a sequel. And it's not like having just one book with your editor and pitching new ones in hopes that they'll buy. Instead, it's, "Yes, you have another book under contract, but we'll figure it out later."
So far, having an option book has been...weirdly cool. Most of the time I think of it as a good thing. I like that HarperTeen had enough faith in me to want another book, even if they didn't know for sure what kind of book. To me, it says they see something in me as a writer. That feels awesome. Seriously awesome. With awesome sprinkles.
I also really like not being tied down to a sequel for the time being. I've seen, through many friends, how hard a sequel can be. It's kinda cool that I don't necessarily have to worry about "topping" book one or falling into the "sequel curse." And I still have a little liberty to write what I'd like to, instead of being obligated to work on the same story whether I want to or not. I like that freedom—I feel like I do my best work under those circumstances.
But there are some things that are pretty scary about an option book, too. I mean, Harper doesn't HAVE TO take any book I write, you know? If you aren't familiar with options, it's still a little like being on sub, but with one editor/house as your audience. I give them a book as a possible option, and it's completely within their right to say, "No, this isn't quite what we're looking for from you."
Yup, my book can still be rejected.
Granted, I get to submit over and over to my heart's content (or until they like what I offer), but that whole possibility of rejection is still there. I'm starting to realize that it'll never go away. Putting your work out there never stops being scary, even when you have an agent and an editor and a book deal.
In the end, I'm totally happy to have an option book, especially because I love my editor and am excited to keep working with her. But like most things in publishing, it's not a perfect scenario. It comes with its own personalized bits of stress, different from other scenarios, but still valid. The more I get used to being "Future Published Author" me, the more I realize that no scenario is ideal. They all come with different pros and cons, and you deal with them as best you can. It's always better to focus on the good things about your personal path, instead of looking at what others got.
So yay option book! Even if you scare me sometimes.