I often consider why in draft writing we try to cling to everything as writers. Backstory goes in, exposition goes in, the kitchen sink goes in. I consider the exposition in John Carpenter’s The Fog, hence the reference to the leper colony. The lepers in that story become first the monsters and then the avenging hand. We realise the monsters were the ancestors of the towns people and not the poor lepers. To make that reveal there has to be some exposition delivered by the wonderful Hal Holbrook as Father Malone who reads the exposition straight from a diary.
However, when does exposition become too much, when does telling become wearing? We are told as writers to show not tell but this an over-simplification of the idea of beats in a story, the rise and fall of tension in tale, in a scene. We have to live the beats, not tell them but exposition does have its place when it comes to pace. If we start on top note in story, with a gunshot, a riot, a terrible murder, then there is nowhere to go but towards hysteria or down into the mundane. There are exceptions, the wonderful Secret History by Donna Tartt starts with a death but this is delivered as a piece of exposition, and it is the aftermath and the affect of the death we explore.
I always like to think that stories are about extraordinary people in ordinary situations (see any Superman film) or ordinary people in extraordinary situations (see everything every written) but for either one to work there does need to be some exposition. Gabriel Garcia Marquez had a deft hand in telling you stuff, here is a town, these are the people, open it up and welcome all the crazy things that happen. Charles Dickens reveled in exposition, he positively washed in it after every meal. So when did exposition become a dirty word? I think film killed exposition because you can’t have a blank screen and tell the audience what is happening. I think film also gave birth to bad exposition because no matter what you think of it, Marquez wove it in to the lexicon of his work, One Hundred Years of Solitude brims with it, Dickens used it as a hammer on social issues in all his books, but when they were at their best it would come and go in the blink of an eye. See Great Expectations. There is good exposition, exposition that flows from the character like a friend sitting down to tell you tale, like a Greek myth, like a horse full of soldiers, a golden fleece and monsters made by Ray Harryhausen reaching down to pluck exposition from the sand.