Irony *dramatic* -
When the audience knows something that the character(s) do not.
Why an author would use this-
An author may use this in a story to add a sense of humor to their book or movie. It also helps the reader understand what is going on before the character does.
1.The Giver- The audience knows that Elsewhere is death, but Jonas doesn't and Jonas knows Gabe is destined for Elsewhere, never to be seen or remembered for all eternity.
2.Herbie- The audience knows that the car is a living vehicle with a mind of it's own, always causing mishaps. However, many of the characters don’t know the slug bug is winning the races, not the driver.
3.The Hunger Games- Katniss thinks Peeta is dead when she is left to fend for herself in the arena, but the audience knows he is not, and enjoy the terror, anger, and actions that Katniss does to attempt to locate Peeta.