History Main / ChekhovsBoomerang

* Not to forget Tucker's Sword in ''Machinima/RedVsBlue''. First it's a sword, then it's a key. [[spoiler:And when you think they are just going to use it like a sword some more, there are two other instances of them needing to use it as a key!]]

* Paula's Pray ability in ''Videogame/EarthBound'' starts as a useful, if unpredictable skill, that takes a back seat to her more reliable psychic powers. [[spoiler:Then you need to pray for a chance of beating the final boss.]]

** Well, not completely true: There are a few characters in [[Anime/FullmetalAlchemist the 2003 anime version]] that never appear again, but they're just in {{Filler}} episodes. Even then, some of them still have a (slight) impact on the plot.

** Klavier's ring. Klavier accidentally left it behind after sleeping with Apollo, telling Daryan that he lost it after sleeping with a groupie. Apollo tries to return it after he reunites with Klavier, but Klavier lets him keep it because it would be suspicious for him to get it back. [[spoiler: When Phoenix finds it in Apollo's room after Apollo suddenly leaves, he realizes that Apollo and Klavier, whom he thought were simply colleagues, were actually lovers.]]

* ''Fanfic/SonOfTheDesert'': Edward snarks about Roy not knowing anything about Ishvalans after Ed manages to talk Scar down in Ishvalan without Roy knowing what they're saying. Roy later learns enough language and culture to apologize to Edward in Ishvalan. [[spoiler: In the story's climax, Roy gives Ed a traditional marriage proposal.]]
* ''Fanfic/ThousandShinji'': Shinji keeps several magic jars storing four [[SpaceMarine Rubric Marines]], and he makes repeated use of them, but at the end it is [[spoiler:the ''TabletopGame/{{Warhammer 40000}}'' gods who emerge from them.]]

-->Twilight twisted around—and around and around and around—looking at her cutie mark, scared that it might have changed; it had not. Adorning Twilight’s flank was a pink six-pointed star surrounded by smaller white stars. “What—? No! The stars represent the spark of magic!”
-->“They do,” Celestia confirmed. "Is it so hard to believe they might also represent stars?”
* In ''Film/GuardiansOfTheGalaxy'' it's mentioned about halfway through the movie that a group of people successfully controlled an Infinity Stone by sharing the burden. Near the end of the movie, the Guardians use the same method to stop Ronan using the Power Stone. In prompt 50 of ''[[https://archiveofourown.org/works/18270659/chapters/45904030 Calling You Out]]'', Quill makes everyone grab onto Tony when he uses the Infinity Stones to erase Thanos' forces, which allows him to survive, albeit with a crippled arm.

* ''Manga/OnePiece'' does this frequently with some of the LoadsAndLoadsOfCharacters (like [[spoiler:Hatchi]] and [[spoiler:Laboon]]) ending up important hundreds of chapters after they were introduced. In fact "Oda never forgets" has become something of a meme among ''One Piece'' fandom.

* Bleach: Ichigo's nature as a hybrid is used many times in the story ([[spoiler: Holliw Ichigo claims that he's the spirit of his Zanpakuto. In Thousand Years War arc, it's revealed that [[CassandraTruth he's manifestation of Ichigo's Shinigami powear as Zanpakuto][]]).

* ''WesternAnimation/ScoobyDooWrestlemaniaMystery'' has Scooby-Doo's imitation of Wrestling/SinCara's dance moves. Scooby initially uses them to win a video game and be invited to WWE City. Later on, he's hypnotized and unknowingly uses the dance to steal the championship belt. Finally, when being forced to fight for his and Shaggy's freedom against Wrestling/{{Kane}}, he uses the dance at Shaggy's suggestion and near-effortlessly fends off the fearsome wrestler.

* Used several times throughout ''WebVideo/StampysLovelyWorld'', but most notably, the You Again Cloning Contraption, which manages to be a plot device for over ''seven'' years. It was first used in Episode 179, "Cloning Contraption", to clone another Stampy Cat to [[MundaneUtility help with the building]] of the Soggy Sandwich restaurant. Then it's used again in Episode 184, "Clone Calamity", where [[spoiler:[[MesACrowd HitTheTarget]] makes a CloneArmy and [[CloningGambit attacks]] Stampy and Lee using it, and Lee also clones himself to help with the fighting. All the known clones at the time died in the episode, and Stampy breaks the button which would enable the machine to work]]. Later in Episode 356, "William Beaver", the new Helper, William got curious and decided to clone himself with the machine, once again to help with construction. Finally, [[spoiler:in Episode 700, ''Tragic Day'', [=HitTheTarget=] and Veeva Dash recycle their past plan and decide to clone an army of dogs large enough to ZergRush Stampy and his own wolf pack, which proved to be disastrous on both sides, considering that the villainous duo ''still lost the battle'' and three of Stampy's own dogs died in the crossfire, which prompted Stampy to destroy the machine once and for all]].

* In ''VideoGame/{{Shantae}} and the Pirate's Curse'', the Palace Disruptor Cannon is first used to accidentally open a path into the last Den of Evil and apparently incapacitated for the rest of the game when a component needs to be replaced before it could be fired properly [[spoiler:only for it to return at the end of the game during the battle against the TrueFinalBoss when [[PirateGirl Risky]] hijacks it and uses it to help Shantae blow the Pirate Master up to kingdom come]].

* In ''ComicBook/SonicTheHedgehogArchieComics'', Dr. Eggman uses the blue Chaos Emerald to initiate a CosmicRetcon, turning Mobius into its video game counterpart. Sonic fixes this a few issues later, going Super and shunting things back to normal, but the Chaos Emerald disappeared. Two years later, and it's shunted into the ''ComicBook/MegaMan'' universe, setting the stage for [[ComicBook/SonicTheHedgehogMegaManWorldsCollide the two franchises' crossover]].

** ''Series/PowerRangersTimeForce'' has the Electrobooster which is used for its function in the episode it is introduced, and then gets stored in the teams hideout where it comes back to play a part in the AllYourBaseAreBelongToUs finally.

*** Wendy picks up on Irene's ability to enchant other objects and people with her own magic to get out of a BodySwap and power up Erza's sword. [[spoiler:When faced with Acnologia's disembodied soul, Wendy uses this technique to [[AllYourPowersCombined transfer her and the other Dragon Slayers' magic into Natsu]], which proves to be [[PhlebotinumOverload more magic than Acnologia can handle]] when Natsu slams all of it into him at once while he's paralyzed by Fairy Sphere's activation.]]

** Aang's bison whistle.