Bob has had something since childhood that is important or shows that he\'s important
Needs a Better Title, might need a better description. --- Bob and Alice need to find the Amulet of Bel-Hazar, but they have no idea where to look -- the old king gave it to his long-lost son, who could be anywhere. It's hopeless! Bob sighs, and begins to fiddle with his necklace. Alice takes notice, and blinks... "Bob, where did you get that?" She asks. "Oh, this? It's just something I've had since I was a kid." It's the amulet, which means...Bob really is the son of the king, the chosen one, the prophecied hero, et cetera et cetera! ...So basically, this is a trope for when something a character has had since childhood turns out to be very plot-important indeed -- either the object itself is important (it's magic, it contains a MacGuffin, etc), or the character who carries it is proven to be important because of the object (someone, at some point, thought this very important thing was safe with this kid). Either way, it's something they've had since childhood. Often, they don't know how they got their hands on it, just that they've always had it. Usually a Chekhov's Gun, brought up early in the story then ignored until the moment it's shown as important. See also Orphan's Plot Trinket and Memento MacGuffin. A sort of pre-obtained Plot Coupon. Compare It Was with You All Along, in which the entire object of the quest is to find this.
Examples:Anime And Manga