How do I create a character... Hmm...
Usually, a character congeals in my mind, and the story forms around him or her. Supporting characters appear as necessary. While I'm most comfortable in the fantasy genre, I've played in others, and my method is more or less the same.
One time, Hubby and I made the mistake of letting another 'writer' in on one of our stories, and this person wanted to pretty much steal the show. In the interest of trying to play nice, Hubby invented a character to counterbalance the Gary Stu/walking god complex character of the other writer's invention. Hubby's off-the-cuff guy ended up so interesting, that we kept him around even after scrubbing the third writer and his character from the story. After some vigorous pantsing, we discovered that Hubby's new character fit very neatly into some previously established intrigue and adventure, and pretty much made the rest of the story.
I've never co-written anything before! I never thought it was a very good idea. But now I wonder....
You make me wish I had a co-writing husband You know....maybe a decade from now