When you're writing do characters come first or situations?

It’s funny I haven’t really formalised my process in years.

Generally I go:

1) Conceit
2) Core Character outlines
3) research
4) plot premise
5) plot structure
6) Side characters
7) Scenic Breakdown
8) Draft 1

But I don’t have a hard and fast system right now so your mileage may vary. Especially since I also bounce back and forth between layers organically as it grows.