You may not even remember this, Chris, but I actually did steal an idea from you once. Sort of. We were at ICFA when you mentioned a half-developed thought about a story that you either wanted to write or had written. About a year later I had an idea for a story and wrote it, and about six months after that I realized that my story had clearly been sparked, in the back of my mind, by the idea you'd described.

So I told you, and your response, as I recall, was pretty much, "Oh, you went a completely different direction than I would have anyway."

Which I mention for two reasons: first, because although you may not know how to respond to an accusation that you stole someone else's idea, you provided an excellent model of how to react to the news that someone stole your idea. And second... you know what? Our stories really did go in totally different directions. Nothing really in common except an initial germ. It was a great notion, but I could just as easily have "stolen" an idea from any book on the shelf at Barnes and Noble and developed it in a different direction and nobody ever would have noticed or minded. Holly Lisle once shared some interesting thoughts along these lines: http://hollylisle.com/how-to-legally-and-ethically-steal-ideas/.

Broad point being, I think that, except in cases of outright plagiarism, even "stealing ideas" is a perfectly common part of writing, especially in a genre where each work is in dialogue with every other work. What, does anyone think that Spiderman is a totally original story? (And of course you didn't steal any ideas to begin with!)