Samuel Taylor Coleridge's "The Rime of the Ancient Mariner" is a tale which, when examined deeply, defines the importance and power of both nature and the supernatural in the world. Coleridge's poem, therefore, shows the importance of a human's recognition that all parts of the world one lives in should be recognized as being important--from the ocean to the albatross (as seen in the poem itself). That said, after the Mariner's killing of the albatross and the death of his shipmates, the Mariner is fated with the forever retelling of his tale. Therefore, the Mariner serves as the conscious personified.
The wedding guest, on the other hand, is the one who hears the Mariner's tale. Given that the Mariner suddenly approaches him and begins to go into his story, the wedding guest is taken aback. Annoyed by the intrusion, the wedding guest seems irritated by the interruption to his good time. In the end, the wedding guest realizes the importance of the Mariner's tale and changes his attitude.
The function of the wedding guest is two-fold. First, the wedding guest functions as the receiver of the Mariner's tale. While this is rather superficial, it fulfills the Mariner's fate to retell his story and pass on the knowledge of the importance of the things both natural and supernatural in the world. Secondly, the wedding guest functions as proof that the passing on of the Mariner's tale is important. Without the change in the wedding guest, the story and the Mariner would be of no importance. Given that the Mariner's story changes the wedding guest, the passing on of knowledge from old to young and experienced to inexperienced proves to be of great importance.