Cheree at Justified Lunacy is hosting a blogfest featuring secondary characters on July 8th. I've signed up, and so should you. It was kind of hard choosing a good scene, though. I find I use secondary characters especially, though I hope not too much, for humor. They bring light and nice counterweight to many scenes. I also like the character who only appears once but does a great star turn and is vital to the plot.
I would never draw a major character entirely from a single real-life person, but with secondary characters I find it fun to do so. For instance, for the past four years I've worked with someone who is not only very talkative but who assumes that anything connected with her life, no matter how trival, is of absorbing interest to everyone around her. Were I a real writer, instead of "telling" you this, I would be "showing" you, by reproducing the classic "I saw this bag in my freezer and I thought it was mangoes but actually it was carrots" conversation, as well as the immortal "I went to get my watch fixed and it wasn't ready and they said come back in a week" drama, but around this time of day energy tends to flag. Anyway, should I complain? I wrote her into a story this weekend.