I...wow. It was a combination of things, IIRC. It began with Matt Wallace from VF (and at the time Murky Depths) asked me to write a story for them. So a big inspiration was the challenge of coming up with something new I thought would kick the ass of an editor and writer I really respected.
So, I started thinking about steampunk because I liked it and I was pretty sure VF hadn't really done any. But I tend to love steampunk that has lots of weird stuff in it, not just cool technology that was ahead of it's time. And then I thought about the goggles, and why someone would really need them. And also, what was the point of divergence. I didn't really have all this stuff figured out in my head - I'm not the best at outlining, although I like to think I'm getting better - but it was all swimming around up there so I just dove in and started writing it. After I figured out the first sentence of the first story, I started to have a pretty good idea of what I wanted to see in this world and story. And then I started sprinkling in more weird stuff (golem constables, grounders, vampires, monsters, etc.) as I went along.
When I wrote the second one, I knew I wanted it to focus on a golem constable because Lucy's attitude of being so willing to try and kill one if necessary felt like misguided prejudice. That and I've always been a fan of characters who can't actually speak, for some reason. And...I just wanted to see a golem fight a bunch of vampires.
Thanks for asking!
BTW, it's about time you started up one of these threads yourself, man. What are you working on now?