Good reading.
After I decide I’ll need a character, I typically use a random picker to give me a list of traits/hobbies/allergies/phobias, and I’ll see if any work for what I want out of the character. If it’s a marginal character, I’ll pick more freely. If there’s a specific/important reason for the character, I’ll be more selective and reselect until I get something closer. And, after I select, I will record them (I’ve got dossier files for each character) – this is perhaps the most critical, because if I work with the character later, I can keep him/her consistent.
At the threat of a mild spoiler, this process helped me this week, because a character needed to eat a lot of a particular food. As I was editing his dossier to make it his favourite, I noticed that I had previously made him allergic to it. This suddenly made the character richer in his personality for deliberately eating something he’s allergic to (and suffering the consequences of it later), and strengthened the plot a bit since I no longer had to make it ill-prepared food.
So, for me, my process helps me, helps me have a diversity of characters with different traits, and it helps me when writing because it can fill in those awkward moments, like, when one character gives a gift to somebody else, where the friendship is deep, then what’s the gift?
My day job involves software so I have to be very rational, logical, and considering subtle nuances; this is something I carry over into my writing. So, maybe somebody else will find my process useful.