The ages of Keith and Malicia were never specified in the book, but they were both young children, with Keith constantly being called a kid and Malicia being explicitly too young to marry (which in medieval Europe meant pre-pubescent). In the film, they are both apparently teenagers.
Teenagers get called "kid" all the time, and Bad Blintz isn't medieval Europe, it's Century of the Fruitbat Discworld. Maybe Terry saw them as younger than this, but he didn't put it in the book either way.
Teenagers get called "kid" all the time, and Bad Blintz isn't medieval Europe, it's Century of the Fruitbat Discworld. Maybe Terry saw them as younger than this, but he didn't put it in the book either way.