Krista and Marion (not married!) were quite the funny pair as they taught how to create protagonists we want to win, villains we love to the, and secondary characters we couldn't live without.
Krista handed out the best, fastest most helpful character bio. Ever.
Here are a few of ideas for developing in depth characters:
Why will the leader like this character?
I thinking writing down this kind of information for your characters is helpful. It's also good to have it close by while you write.