So. It's a known thing in fiction writing that some bits of it will flow automatically for you and some bits you'll have to kind of work at, and which bits are which will vary from person to person. Naming characters, for example, appears to be pulling teeth for some of my friends and easy-peasy for some of my friends and somewhere in the middle for others. Right? And I have a technobabble generator lodged behind my eyes, among other things. If you say that we're doing xenobotany, I can give you xenobotany terms about the quasi-stamen and the carnivorous sympodial group until the trilete spores reconverge. And move on with the rest of the story, 'cause that's how I do.
Okay, so the new law of the universe is: there is an inverse relationship between how long it took you to come up with something and the likelihood that an interviewer will ask how you thought of it. "How did you come up with _____?" might be the thing you can honestly answer by saying, "Well, it's interesting you should ask that, Interviewer, because here is an answer that is witty and erudite, a little bit self-deprecating, and concise. Haha! Oh, and also brings in a close friend or member of my family who will enjoy being referred to." But the odds are muuuuuch better that they ask you, "How did you come up with _____?" when the answer is, "Um...in my...brain? Which comes up with things and I don't know why? Can you ask me about...this other thing? Because it will be a better anecdote. This other thing I can explain."
Maybe this is not a law of the universe. Maybe this is just me.
Anyway because it is my job to make stuff up, about half the answers to "how did you come up with _____?" are made up. Because, "Dunno, I make stuff up sometimes, next question," is just rude, and also not very entertaining.
It's also true, though. I make stuff up sometimes. Then people pay me. It's a good deal when it works. Sometimes it comes with funny stories about the funny stories, but honestly, sometimes the funny stories are just here because I have spent 30 years or so making my brain into a thingy that makes funny stories. Which...turtles all the way down? Do you suppose that's a good answer? No, I didn't think so either.
I think I might default to, "So I was reading this biography of Woody Guthrie...."
See, there's at least one science fiction idea of mine to which that's an honest answer for "how did you come up with." But now you're not going to know which one.
I bet you couldn't tell I was procrastinating from revisions. Oh wait! I have smart friends. You totally could tell. But the interview question thing really was real.