How do writers create recurring characters in sketch shows?

How do writers create recurring characters in sketch shows?

Robert Morton (Current E.P. of Mind of Mencia) gives expert video advice on: How does writing sketch comedy differ from other types of comedy?; What makes a successful sketch?; How do writers create recurring characters in sketch shows? and more...

It always happens as a by-product of a successful performance - for us. In sitcoms it's more engineered and more written, but on sketch shows and talk shows it's usually when we have a character that comes on the show and is hilarious. We are smart enough to know to bring them back a few times and get that many more laughs.