How much do you tend to know about your characters when you start writing?
This might sound like one of those crazy writer over-romanticizing the craft thing, but when I first start writing a story, I feel like my characters are all strangers. I have a pretty clear impression of their looks and the general vibes they give me, but then I learn more details overtime, things about them that don't seem to fit their first impressions, subtleties that I didn't initially think of and so on.
For instance, the fact that Alicia loves old music and poetry was not originally planned into the story, neither was how messy she is and the fact that she has a bad habit of eating when she's upset. These are things you generally wouldn't know about someone at first glance, so it kind of makes sense for me to "learn" my characters coping mechanisms, bad habits as I move forward and get to "see" more parts of their lives.
Anybody else? Is your process like that or entirely different?