Part of my story is a critique of scientific academia which comes from my own experiential pet-peeves. When I was doing research, I'd see a result and be like "oh, lets check that out! That could be interesting!" - and my PI would invariably say "But what question are we asking?!" - the cult of the exquisite question asking. If you ever listen to dudes like Brian Cox on Insta (good stuff, actually), its always like, "We asked the question, we next asked the question" and on and on. Its essentially code for "My pedigree is intact, i speak your language - my research is fundable...please give a grant".
I tend to go the model-building route. These are the established laws of physics - these are the established forces/variables in my world...what happens?!
I started with no idea where I was going. I designed a plausible viral infection that would hit 75% of the world/US with tiered psychopathy, and then put some survivors in that soup and watched what they did with just a few guardrails - dignity first, agency first.
The ending is now in place, but I had no idea when I started.