History ChekhovsGunman / Literature

* ''Literature/GriffinsDaughter'': Lady Amara mentions her predecessor as head of the elf mage circle had disappeared years ago. A book later, Amara's son - after being sold into slavery by humans - runs into [[KnownOnlyByHisNickname Gran]], an older elf maiden who turns out to be the aforementioned missing mage. (she was there of her own free will, as penance for [[MyGreatestFailure an earlier tragedy]].

* ''Literature/LunarChronicles'': It's mentioned that Princess Selene of the Moon died in a fire as a child, with only a few burned bits of her body left. [[spoiler:It turns out that cyborg protagonist Cinder is in fact Selene, as she was smuggled to Earth and rebuilt after her evil aunt tried to murder her.]]

* ''Literature/RomanceOfTheThreeKingdoms'' inconspicuously introduces Sima Yi as Cao Cao's secretary, and you might not expect much from him in a novel with LoadsAndLoadsOfCharacters (especially considering how the founders of the eponymous Three Kingdoms are introduced). However, Sima Yi eventually becomes Zhuge Liang's rival, before staging a coup during the reign of Cao's great-grandson. His grandson becomes emperor.

** The ultimate Chekhov's Gunman for ''Animorphs'', though, has got to be Crayak. The [[FanNickname Big Red Eye]] first appeared to Jake as a vision at the end of ''The Capture''. For the next twenty books this goes unmentioned, and then along comes ''The Attack'' and the big reveal.

* Abigail Pent in ''Literature/GideonTheNinth'' is a rare example of this being done [[spoiler:posthumously]]. While it initially appears that [[spoiler:she and Magnus were killed opportunistically]], it's not until the final revelations of who the antagonist at Canaan House is that [[spoiler:Cytherea reveals how Abigail nearly ruined her plans in three separate ways: her necromantic specialty in spirit talking had the potential to reveal the culprit behind other murders, her being a historian interested in piecing together Lyctoral history could have unveiled the secrets at Canaan House much earlier, and she had completed the challenge to gain the key to the Seventh House's Lyctoral study, which Cytherea had neglected to clear of traces of herself out of sentimentality]].

** ''Temple'' has Will's brother Martin Race, supposed to be working with the team remotely.

** Though fan attentiveness paid off in ''Half-Blood Prince'' when [[spoiler:Harry gets the fake locket with a note by R.A.B. Fans were attentive enough to guess that R.A.B. was Regulus Black, the brother of Sirius briefly mentioned in ''Order of the Phoenix'' - mentioned all of twice in the series up to that point; we're talking some very attentive fans here - based on the fact that Regulus was mentioned to have run off to be a Death Eater, then was seemingly killed by Voldemort for getting cold feet, which would have made him a good fit though fans weren't told Regulus's middle name.]] In fact, fans sussed this with so little trouble, some fans took it for a RedHerring because it was ''too'' obvious. Rowling's response to the theory was "that's a really good guess."

** Cirrus the [=IceWing=] was first seen in ''The Lost Heir'' as a minor character. But he becomes more important in ''Escaping Peril'', where [[spoiler:Cirrus is revealed to be a [=RainWing=] named Chameleon in a magical disguise, as well as Peril's father]].

** Dragonbit Vipers are briefly mentioned at the beginning of The Brightest Night as part of a ploy by Addax to cause panic. At the climax [[spoiler: Blister murders Burn with one]].
** Cirrus the [=SeaWing=] was first seen in ''The Lost Heir'' as a minor character. But he becomes more important in ''Escaping Peril'', where [[spoiler:Cirrus is actually a [=RainWing=] named Chameleon in disguise, and he's Peril's father]].

* ''Franchise/StarWarsLegends'': A head of one of the smuggling organizations with a subplot in ''Literature/TheThrawnTrilogy'' has bodyguard, and in one line he calls her Shada. She's good at her job. Zahn later wrote a short story called "Hammertong", in which she was an all-around agent who was one of the many people who helped get the Death Star plans to Leia. In the ''Literature/HandOfThrawn'' duology written five years after ''The Thrawn Trilogy'', Shada Du'kal accompanies Talon Karrde on his search for a certain document, and has her own Mystral subplot.

** Though fan attentiveness paid off in ''Half-Blood Prince'' when [[spoiler:Harry gets the fake locket with a note by R.A.B. Fans were attentive enough to guess that R.A.B. was Regulus Black, the brother of Sirius briefly mentioned in ''Order of the Phoenix'' - mentioned all of twice in the series up to that point; we're talking some very attentive fans here - based on the fact that Regulus was mentioned to have run off to be a Death Eater, then was seemingly killed by Voldemort for getting cold feet, which would have made him a good fit though fans weren't told Regulus's middle name.]] In fact, fans sussed this with so little trouble, some fans argued against it because it was ''too'' obvious. Rowling's response to the theory was "that's a really good guess."

*** Draco's mother has been mentioned since ''Philosopher's Stone'' and makes her physical appearance in ''Goblet of Fire''. However, it isn't until ''Half-Blood Prince'' that we learn her name: Narcissa, and the fact that she is Bellatrix's younger sister. She is responsible for making Snape do the Unbreakable Vow [[spoiler:that ends with him killing Dumbledore]] and in ''Deathly Hallows'' [[spoiler:takes a decision that proves critical to Voldemort's defeat]].

** Mrs. Figg is introduced in the first book as Harry's babysitter, and we hear very little of her afterward. She is actually mentioned off-hand in book four as part of the 'old team' but it's very easy to forget about her. In book five, [[spoiler: she's revealed to be a Squib that's been watching over Harry on Dumbledore's orders for the last fourteen years and is the sole witness to Harry's Hearing at the Ministry of Magic]].

** Nadir Khan may be an inversion. He has a fairly important role as Amina's first husband before disappearing from the story. He shows up a fair bit later as Qasim the Red, whom Amina is [[YourCheatingHeart seeing secretly]]. However, his only contribution is as a living plot device, by motivating Saleem to get them to break up.

* In the ''Literature/{{Discworld}}'' book ''Discworld/ThiefOfTime'', the milkman Ronnie Soak is mentioned here and there. Later, it turns out that Soak is [[spoiler:[[SdrawkcabAlias Kaos]], the ''fifth'' horseman of the apocalypse who [[Music/TheBeatles left before they became big]]]].

** There's generally about one a book, it's Simon in ''Discworld/EqualRites'', the Fool in ''Discworld/WyrdSisters'', Lupine Wonse in ''Discworld/GuardsGuards'', etc.

--->''I've got nobody to blame but myself. [[Literature/HarryPotterAndThePrisonerOfAzkaban Sirius Black]], [[Literature/HarryPotterAndTheOrderOfThePhoenix Mrs. Figg, and Mundungus Fletcher]] were all mentioned in passing well before they burst onto the stage as fully-fledged characters, so now you've all become too clever, not for your own good, but for mine. The fact is that once you drew my attention to it, I realised that [[LampshadeHanging Mark Evans did indeed look like one of those "here he is, just a casual passer-by, nothing to worry about, bet you barely noticed him" characters who would suddenly become, half way through book seven, "Ha ha! Yes, Mark Evans is back, suckers, and he's the key to everything!]] He's [[Literature/HarryPotterAndTheHalfBloodPrince the Half-Blood Prince]], he's [[LongLostRelative Harry's Great-Aunt]], [[Literature/HarryPotterAndTheChamberOfSecrets he's the Heir of Gryffindor]], he [[ShoutOut lifts up the Pillar of Storgé]] and he [[SugarWiki/FunnyMoments owns the Mystic Kettle of Nackledirk!" (Possible title of book seven there, must make a note of it).]]''

* In Creator/TadWilliams's ''Literature/{{Otherland}}'' series, the side plot involving Olga Pirovsky is treated with a great deal of significance even though it's not initially apparent how her mysterious headaches have anything to do with the main story. Even when she's tasked by [[TheChessmaster Sellars]] to [[DressingAsTheEnemy infiltrate]] the headquarters of J Corp, it seems like her role is fairly straightforward. Then comes TheReveal, and she turns out to get the biggest SugarWiki/{{Heartwarming Moment|s}} in the whole series.