How does one write a poem about the inevitable?
Presently there's an assumption that a poem should surprise the reader in some way, and frequently some way seems to be defined as character twist, or plot twist, or another sort of fiction-writing twist. It's almost tempting to believe that, in a narrative poem, this should be a natural expectation; for most narrative poems do not use stacks of images as a structural device but depend on dramatic and grammatical movement.
Yet some stories--myths, for instance--have predictable endings that are integral to their power; and this is also true, I think, of novels such as Truman Capote's In Cold Blood. Knowing exactly what is about to happen only makes the tale more intense; and this sense of dread supersedes the author's tinkering with plot and characters.
The Rime of the Ancient Mariner is also inevitable, but it is nothing like In Cold Blood.
If these thoughts sound disjointed, that's because I am thinking them as I write. But it is too easy to imagine that, if Coleridge were to submit the Rime to a twenty-first-century literary journal, he'd get a rejection slip complaining about the poem's predictability.