Liam McGann's blog discusses characterisation. An interesting concept. For me; I let my characters find themselves; sometimes, no often, they surprise me; the direction they take and their contribution to the story different to what I imagined when they took their first step onto the pages of my book. I figure if I'm surprised, so too will be the reader.
That's one way Robin - nothing wrong with flexibility. Other authors make requests for some kind of initial template or base, so they have something to work from. It's all a matter of preference really, but I do get requests for character profiles so looks like they're useful to some writers.
I was not suggesting otherwise, Chris; makes a lot of sense.
@Robin Rendell - I guess a mix between the two tends to be the best option. I tend to use a profile just as a boundary setter - it's still the case that acting out of character is possible, and indeed necessary, but having an idea of the limits of a given person tends to ground them more for me.