What Happened to the Mouse?/Oral Tradition


 * Older Than Feudalism: Homer did this in The Iliad. He went to the trouble of describing the battle between Aeneas (mortal son of Aphrodite) and Achilles. The Gods saw that Aeneas was about to be killed, and, since he was such a good servant, decided that he didn't deserve to be killed, and took him away from the battle, declaring that he would be the future king of all Trojans yet to come. Homer never mentions him again, and even the other authors of the lost epics only said that he either fled Troy after a bad omen or was captured and spared by the Achaeans. Later Greek authors said that he went to Italy. It took eight hundred years for Virgil to turn this into a Brick Joke. An Epic Brick Joke, at that!
 * Open up a mythology book. Chances are, if you're reading the Perseus story, you'll know that Acrisius, King of Argos, simply had bad luck when it came to having children (or at least males), and learned through the Oracle of Delphi that while he wouldn't have any luck any time soon, his daughter, Danae, would have a child that would eventually kill him. After that, everyone knows that Acrisius stuck Danae in a box and put her in the ocean, where Zeus impregnates Danae in the form of a Golden Shower, thus leading to the creation of an important hero. You never hear about Acrisius again until a long time after, especially in your text. Depending on your version, he's more or less become something of a poor man, and happens to be visiting funeral games where Perseus also happens to be playing. As Acrisius sits in the stands, a stray discus launched by Perseus strikes an unsuspecting Acrisius in the head (this troper's mythology guide had Acrisius struck In the foot.), thus fulfilling the prophecy that his son would kill him. The presence of Acrisius itself seems to combine this trope, Brick Joke, and some sort of Chekhov's Prophecy.
 * In many versions of Arthurian legend, Arthur's mother has three daughters with her first husband: Morgause, Morgan le Fay, and Elaine. The first two play pivotal roles in Arthur's life, but Elaine is typically mentioned once in passing and then never heard from again.
 * The wives of both Cain's and Abel's bloodlines for the first several generations come from seemingly nowhere.
 * Elihu spends a few chapters ranting at the eponymous character of the Book of Job, then disappears and isn't mentioned in the last portion.
 * In the New Testament, we never hear any word of Jesus' stepfather Joseph after the "Did you not know I would be in my Father's house" incident when He was twelve. Church tradition says he passed away some time before Jesus started his ministry.