How to make up a character that you need-RIGHT NOW!

Some writers spend months or years delving into their characters. They write long biographies, interview the characters, set up psychological profiles, and figure out what type of ice cream they like. I have done that. Those are all wonderful tools.

But there are times you need to make up a character, sometimes a major character, on the spur of the moment. How the heck do you do that?

First thing is to think of what is the character's function in the story. Are they there to do an info dump? Ar...