What should a character interview contain to be successful where the goals are: characters with strong voice who are established with a distinct 'personhood' (?) and are generally interesting to follow?
Why I'm asking
A common weakness in my writing method is that my characters don't "pop" when I start. I've had a few successes, but its hard to tell when I start a book who those will be. But, I've worked with writers whose characters do pop right away; sometimes immediately in brainstorm sessions, so this is pre-revision. The answer for me is that I clearly need to change the way I think about people or do more upfront work. I'm aware of some basic strategies: give them quirks, do a character sheet, etc.
But, what I think I'm sorely lacking is character voice. I have heard of methods where you "interview" your characters. You have a series of questions and you write in first person as if you are your character, responding to those questions. By the end you have a maybe twenty page document that covers a lot of the things you'd see in a character sheet, but it's in that characters voice.
I'm hoping that a good checklist of points will help me draw out character weaknesses and start differentiating my characters so they aren't all Mary Sues or the same person wearing another hat.
An interesting character is better than an interesting plot. So if I want to write, I need to master this.
Are there known interview methods I'm unaware of? (Books/websites) I've done some googling in the past and never really come up with anything satisfying or intriguing.
Plot/POV/Circumstance Not Enough
I've been writing long enough to understand that you can play with conflict, pov, and all sorts of other things to shift the tone of a book. In my opinion, these are often patch jobs to cover up weak characters. When you read something like Confederacy of Dunces (which if it's good at anything, it's good at characterization) within a few pages you know who these characters are and what direction they'll stray in in most situations. The author of that book is stretching in ways I'm not; and while plot is certainly an element of the final product, the humor, the whatever -- it's not the source of the identity or voice.
What isn't helpful at this time... for this question.
If you have a method that isn't the interview method that would help me I'd like to know about it, but not as an answer. Leave a comment with a link or enough detail and I'll ask a separate question if I need more info.