A plot element that doesn’t get fully developed, perhaps on the assumption that they’ll have the sequel to take care of it. The element can be a relationship, a theme, or a character that clearly has a lot more possible development, but doesn’t get it. The central plot is no less complete and these aspects may have just been there to enlarge the universe, but they're there and available for later use- more story to tell later. Compare Sequel Hook, which only occurs at the end of the story and is specifically geared toward inviting a sequel. Examples of Saved for the Sequel include: