History ChekhovsGunman / Literature

** In the first book, Katniss has a flashback when she meets with a female Avox serving her in the Capitol and Peeta excuses her by noting that that it was because she looks like Delly Cartwright, their friend back in District 12. The Avox is later revealed in ''Mockingjay'' to be named Lavinia [[spoiler:and is killed by the Capitol to torture Peeta during their attempt at hijacking him]]. Delly Cartwright, meanwhile, also debuts in the same book [[spoiler:to help Peeta fight off said hijacking.]]

** Dragonbit Vipers are briefly mentioned at the beginning of The Brightest Night as part of a ploy y Addax to cause panic. At the climax [[spoiler: Blister murders Burn with one]].

** Most notable is Thomas Theisman, who shows up in ''Honor of the Queen'' and has a minor role (well, not that small, but still, he's not even a secondary character). Then he appears briefly in ''The Short Victorious War'' and ''Flag in Exile'', presumably due to the LawOfConservationOfDetail, and takes a gradually bigger role in the narrative, until he finally [[spoiler:overthrows the evil government of his own country, restores the truly democratic one that hadn't existed for two centuries, beats the crap out of the Royal Manticoran Navy, rides to their rescue with ''his'' navy after they've had the equivalent of Pearl Harbor pulled on them and then signs a military alliance with them, shares a flag deck with Honor Harrington herself, then does some more awesome stuff... and he probably hasn't finished, as he has ascended to be a series anchor in a WorldOfBadass]].
** Honor's mum, Allison Benton-Ramirez y Chou Harrington. Mentioned briefly at the beginning of the same book as Theisman, she becomes more and more relevant from ''In Enemy's Hands'' on. Not to mention that by ''A Rising Thunder'' we find out that [[spoiler:her brother is a Very Big Fish in the Beowulfan government]]. Of course, this branch of the family was mentioned earlier, but still...

* Creator/ChinaMieville's loves this trope in his ''[[Literature/BasLagCycle Bas-Lag]]'' novels.
* In a party scene in ''Arrow's Flight'', the second of the Literature/HeraldsOfValdemar novels, a throwaway line mentions Queen Selenay sitting next to a Herald with streaks of white in his hair at either temple. This turns out to be Herald Eldan, who has a significant role in ''By the Sword''.
** Similarly, both Herald Lavan Firestarter (''Brightly Burning'') and Herald Vanyel (''The Last Herald-Mage'') are mentioned as historical personages long before Creator/MercedesLackey wrote a book/trilogy about them.
* In Creator/SandyMitchell's first ''Literature/CiaphasCain'' short story, we are introduced to Cain's rather smelly and loyal [[SideKick aide]] Jurgen, who doesn't look like he'll have much relevance except for jokes on how he puts people off with his atrocious hygiene standards. [[spoiler: Later on, it turns out Jurgen is an ''extremely'' potent "blank," someone who negates psychic powers and harms daemons simply by being in proximity to them, and his becomes a constant and critical plot point throughout the rest of the novels]]. His absolute loyalty and obedience to Cain also play important roles.

* Butcher also does this a bit with ''Literature/CodexAlera'' -- only the gunman turns out to be a "gunspecies". Tavi and Kitai go into the Wax Forest for a test and end up not only encountering the wax-spiders, but also an unusual new creature [[spoiler:The Vord queen]]. They're mentioned in passing during the first book -- but show up in each new one, getting more dangerous each time.

* ''Literature/TheDresdenFiles'' is very prone to this - the main opponent of a book will almost definitely be someone who was introduced in an earlier book, quite possibly ''Grave Peril''.
** ''Literature/TurnCoat'' has another major one: [[spoiler:The obnoxious little secretary wizard who tries to get Harry to sign for a folder he was getting off the record turns out to be (one of) the traitor(s) on the Council. And he was actually trying to get Harry to sign because he was using special ink for signatures to screw with the wizards' minds]].
** Said character was actually introduced as far back as ''Summer Knight'' in passing.
** Along side this character was a woman who was described as old and holding a scepter. It is later revealed to be Anastasia Luccio, who is Captain of the Wardens, [[spoiler:eventual lover of Harry Dresden]], and [[spoiler:brainwashed victim ordered to kill]].
** Molly Carpenter. Initially just one of Michael's many kids, she is first mentioned in passing in ''Grave Peril'' by [[spoiler:Lea, Harry's fairygodmother]] briefly appeared in ''Death Masks'' as a background character. She becomes a major player in later books when she [[spoiler: begins to manifest magical abilities and Harry takes her as an apprentice]]. At the end of ''[[Literature/ColdDays Cold Days]]'', [[spoiler: she becomes the new Winter Lady]].
** Mab, Queen of Air and Darkness, gets name dropped by Harry as far back as the first book ''Storm Front''. She would end up becoming a major player in really short time.

* Also done in books two and three of Cinda Williams Chima's HighFantasy smash hit, ''Literature/TheSevenRealmsSeries''. In book two, [[TheHero Han]] convinces ActionGirl Catarina to study at the temple school at [[AcademyOfAdventure Oden's Ford]], an area of the school known for producing the most refined maidservants in all of the Seven Realms. In book three, Han needs someone he can trust near [[RebelliousPrincess Raisa]], but someone that can also defend her. Turns out those skills Cat got came in handy.

* In ''Literature/WhenYouReachMe'', the laughing man seems to have no purpose in the book, but in the end, we learn that [[spoiler:he's one of the main character's friends who has traveled back in time to save one of her other friend's lives]]
* {{Lampshade|Hanging}}d in the first ''Literature/ArtemisFowl'' book with the introduction of Chix Verbil, whom the narration says will become important in sequels, but "for now his only function is to press a button to activate the time-stop".
** Played straight with [[spoiler: Turnball Root, appeared in a short story and reappeared in the ''Atlantis Complex''.]]
*** That sprite who told [[spoiler: Turnball]] how to re-acquire some magic? That's the first supernatural being who ever appeared on-screen: the fairy who loaned Artemis a copy of her Book way at the beginning of the series. Given that she hadn't appeared since the first chapter of the first book, and this was the ''seventh'', this probably is also a BrickJoke.
* In the very first book of ''Literature/DoraWilkSeries'', one of the magicals Dora saves from the Thief is a werewolf named Jędrzej. Come the ''final'' book, and he appears as an informant for her, claiming he's indebted, and by the end of the book he [[spoiler:becomes the new alpha of Thorn]].

-->''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 ''Literature/TheManualOfDetection'', a sleepwalking custodian named Arthur appears to be a BitCharacter. [[spoiler: Turns out he's the overseer of the Agency]].
* In the Legends trilogy of the ''Literature/GuardiansOfGaHoole'' series (books 9-11), a character named Theo is introduced midway through book 9, and he becomes the first blacksmith and creates the first battleclaws, but that's about it. However, later on, in book 13, it's revealed that [[spoiler:Theo wrote the holy scriptures of the Middle Kingdom, and as such is directly responsible for the pacifist lifestyle of the owls of the Middle Kingdom, as well as being indirectly responsible for all the events involving the Striga, an escaped Dragon Owl who allies himself with [[BigBad Nyra]] and the Pure Ones in book 15.]]
* ''Literature/TheFourFeathers'' has Abou Fatma. He appears briefly in an early chapter, delivering [[UsefulNotes/TheRiverWar General Gordon's]] letters to Jack Durrance, in a moment that merely establishes him as an Arab loyal to the British. He doesn't reappear until the very end, when he's revealed to be Harry Faversham's friend and [[spoiler:helps him and Colonel Trench escape from prison]]. In the 2002 film he's given a [[AscendedExtra much larger role]].
* 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.
* Ezra Jennings from Wilkie Collins's ''Literature/TheMoonstone'' is the ''assistant'' to Dr. Candy, himself a side character. [[spoiler:Both of them, but especially Jennings, are more important to the plot than the reader might first think]].
* ''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]].

** Also from the first book, after Katniss shot an arrow at the Gamemakers she said that one of them tripped backwards into a punch bowl. She has a little interaction with him during her pre-Games interview, then he is never mentioned again. Until the next book, ''Catching Fire'', when she formally meets him and finds out that his name is Plutarch Heavensbee and he is now the Head Gamemaker. At the end of ''Catching Fire'', she finds out that he is ''also'' [[spoiler: part of a Capitol rebel group, and helped orchestrate the plan to break the victor-tributes out of the Quartel Quell arena]]. He then becomes a major character in ''Mockingjay'' and a significant player in the [[spoiler: war effort for the rebels]].
* ''Literature/TheCampHalfBloodSeries'':
** A lot of gods/mythological beings tend to be mentioned much earlier than their physical debut. Below are just the notable examples:
*** The Twelve Olympians are mentioned by name in ''The Lightning Thief'', but they are introduced sequentially, with only Dionysus, Ares, Poseidon, and Zeus appearing in the book. Demeter doesn't make an appearance until ''The Last Olympian'', four books later.
*** Aeolus is mentioned one book before his debut in ''The Lost Hero''.
*** Nemesis and Hecate are similarly second series deities who are mentioned in the first (they are said to be serving the Titans).
*** Tartarus has been mentioned now and then, but only becomes important in ''The House of Hades''. Justified since up until then, he is only considered a place by most (as the prison for the worst of the worst), so the revelation that he is a deity (and the father of the Giants, no less) comes as a genuine surprise for everyone.
*** Rhea gets a blink-and-you'll-miss-it mention in ''The Lightning Thief''. She doesn't appear until ''The Hidden Oracle'', ''two series and ten books'' later.
** The little girl Percy spots sitting near the camp bonfire in ''The Lightning Thief'' is revealed to be Hestia, the titular character of ''The Last Olympian''.
** Circe's female staffer who serves Percy in ''The Sea of Monsters'' is reintroduced in ''The Son of Neptune'' as Hylla Ramírez-Arellano, the current Queen of the Amazons.
** Will Solace has been mentioned since ''The Last Olympian'', but it isn't until ''The Blood of Olympus'' that he plays a substantial role in the fight against the Romans. As of ''The Hidden Oracle'', he is Nico's boyfriend.
* Emile Zola ''loved'' to use this trope in his ''Les Rougon-Macquart'' series. A character mentioned in passing in book one and described by his father as a forgettable good-for-nothing shows up as the main character in books 10 and 11. Another one mentioned in passing in book 3 is the main character of book 14. The pattern repeats itself throughout the books. Things get even more confusing when you find out that the books do ''not'' follow in chronological order and that the timelines of most of them intersect in one way or the other. Trying to keep up with who is doing what and is important in which book can become a nightmare.

* In ''Literature/SilasMarner'', the character Godfrey Cass is seemingly of no direct importance to the main plotline, until his brother robs Silas, and then his secret daughter ends up in Silas's care. Small world!
* ''Literature/TheStarsMyDestination'', in a way. Just keep an eye out for the doctor in the dream Dagenham subjects Gully to.
* 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.
* In J.C. Hutchins'a ''Literature/SeventhSon'' trilogy, characters like Special K, Peppermint Patty and Klaus Bregner get throwaway mentions only to become very important later on.
* In ''Literature/TheSilmarillion'', Lúthien Tinúviel is introduced off-hand by Tolkien simply as the daughter of Thingol and Melian, but later, as we all know, plays a major part in [[spoiler:retrieving a Silmaril]] by owning Sauron's face and tricking Morgoth himself and proving herself to be totally badass.

** ''Six Sacred Stones'' introduces Jack West's brother in law and previous neighbour in a flashback.
* In the ''Literature/YoungWizards'' books, there are a decent number. Two of note are Ponch, who in an incidence of ChekhovsGun does indeed get stranger the more time he spends with Kit, as wizards pets do. He crosses into and even creates alternate realities and is implied [[spoiler:to maybe be God. Who apparently likes palindromes.]] The other is Biddy in ''A Wizard Abroad'' who is the local smith and farrier and [[spoiler:turns out to be one of the Powers That Be and helps reforge a powerful artifact that has been lost]].
* ''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.

* In ''Literature/TheChroniclesOfAncientDarkness'', The Walker, a crazy old man, is introduced in the 1st book, but it isn't till the sixth that we learn [[spoiler: he is the 7th Soul Eater.]] He did give us some hints, though, like when he said that before he went insane, he was "a very wise man".
* In ''Literature/TheCavesOfSteel'', R. Sammy, a robotic courier, is the first "person" we meet in the book, but he seems more of a simple narrative device to provide an opportunity for {{exposition}} about the Earthmen's dislike of robots. Much later on, [[spoiler:he is found destroyed, and it turns out he was a critical part of the book's murder plot - the one who sneaked the murder weapon into the area before the crime]].
* Sarah Caudwell's ''Literature/HilaryTamar'' mysteries have a tendency to mention elderly relatives of the protagonists in passing who will become crucial to later books in the series. The first book, ''Thus Was Adonis Murdered'', mentions that Cantrip has an uncle who's a Second World War veteran; he ends up providing some crucial exposition and a BigDamnHeroes moment in the third book ''The Sirens Sang of Murder''. ''The Sirens Sang of Murder'' in turn mentions Julia's Aunt Regina, who narrates a sizable fraction of the fourth book, ''The Sibyl in Her Grave''.
* Creator/RobertRankin's ''[[Literature/HollowChocolateBunniesOfTheApocalypse The Hollow Chocolate Bunnies of the Apocalypse]]'' has a literal example when [[spoiler:Jill]] shows up to shoot the BigBad and rescue Jack at the very end.
* A few of the main characters in ''Literature/ThePaleKing'' go unnamed in their introductory chapters.
* Literature/InDeath series: At one point in ''Loyalty in Death'', an old man mentions how he has met with two guys with dead eyes who are just the muscle and working for terrorist organization Cassandra. [[spoiler: The two guys become the murderers to hunt down in the ''Survivor in Death'' story]]. In ''Judgment In Death'', a blonde-haired assassin working for Max Ricker kills off a mook who was going to reveal a lot of details. [[spoiler: The blonde-haired assassin turns out to be Max Ricker's daughter and she becomes the murderer to hunt down in the ''Promises in Death'' story]].
* The third chapter of ''Literature/InDesertAndWilderness'' randomly introduces two nice Englishmen. [[spoiler: Who go on to rescue the protagonists from their final predicament]].

* Many examples in ''Literature/SeptimusHeap'': Syrah Syara, Merrin Meredith, AgnesMeredith etc.
* In ''Literature/LunarChronicles'' by Marissa Meyer, it is mentioned that Princess Selene of the moon had died in a fire- but that no body had been found, just some pieces of burnt flesh. Turns out that Cinder- the cyborg protagonist- was really [[spoiler: Princess Selene, who had been rescued successfully and had been given artificial replacement parts!]]
* In ''Literature/DangerousFugitives'', Wilson appears to just be a deputy to the BigBad. [[spoiler: He ends up saving the day]].
* In ''Literature/TheLongEarth'', Rod Green is first introduced as a son of a family which intends to colonize a parallel Earth. Unfortunately, he cannot "step" to parallel Earths, so his family abandons him. He shows up a couple more times where it becomes apparent that he resents his family for his abandonment, but only features prominently when [[spoiler:at the end of the novel, where he blows Madison, Wisconsin up with a nuclear bomb]].
* Creator/CSLewis in ''Literature/TheSilverChair'' has a particularly devious one. Jill and Eustace are sent to look for the kidnapped King Caspian's son. Halfway through their journey to the place where the prince disappeared, they find a delightful young damsel escorted by a silent knight who doesn't show his face. [[spoiler:If you haven't read the book, you have correctly guessed by now that the knight is the prince that they were looking for. However, the damsel is, in fact, the BigBad that appears to the children to point the direction of a castle inhabited by giants for whom humans are refined cuisine delights. And the children never even suspect about the identity of the two strangers until the climax of the book]].

* In ''Literature/NativeSon'', Bigger sees Buckley's face on a campaign poster early in the story, long before being prosecuted by him for rape and murder.
* Prince Oswin notes in the very beginning of ''Literature/TerraMirumChronicles'' that anyone useless is disposed of during a revolution. So why is Erebus still alive after the Nightmare Queen has everything she should need from him?
* In the ''Literature/CircleOfMagic'' quartet's first book, Tris mentions to Niko that she has a cousin Aymery at Lightsbridge. In Circleverse, Aymery is as common a name as Steve, so when she hears it on the wind in ''Tris's Book'' she dismisses it as coincidence. Aymery himself arrives at the Winding Circle temple to visit a bit later [[spoiler:acting as a spy/saboteur for the pirates who want to raid the place]].
* ''Literature/ProvostsDog'' mentions King Roger's new young wife in the first book, ''Terrier''. In ''Mastiff'' it's revealed that she is basically responsible for his actually making himself a [[RoyalsWhoActuallyDoSomething responsible king]] instead of a rake with a crown, as he didn't want to embarrass himself when she kept asking him questions about the management of the realm. (Of course, this pisses off all the nobles who were quite happy to have an IdleRich king, so Beka meets Jessamine after her son's kidnapping in an elaborate usurpation plot.)
* The ''Literature/HonorHarrington'' series has a few.
** Most notable is Thomas Theisman, who shows up in ''Honor of the Queen'' and has a minor role (well, not that small, but still, he's not even a secondary character). Then he appears briefly in ''The Short Victorious War'' and ''Flag in Exile'', presumably due to the [[LawOfConservationOfDetail Law of Conservation of Detail]], and takes a gradually bigger role in the narrative, until he finally [[spoiler:overthrows the evil government of his own country, restores the truly democratic one that hadn't existed for two centuries, beats the crap out of the Royal Manticoran Navy, rides to their rescue with ''his'' navy after they've had the equivalent of Pearl Harbor pulled on them and then signs a military alliance with them, shares a flag deck with Honor Harrington herself, then does some more awesome stuff... and he probably hasn't finished, as he has ascended to be a series anchor in a WorldOfBadass]].
** Honor's mum, Allison Benton-Ramirez y Chou Harrington. Mentioned briefly at the beginning of the same book as Theisman, she becomes more and more relevant from ''In Enemy's Hands'' on. Not to mention that by ''A Rising Thunder'' we find out that [[spoiler:her brother is a Very Big Fish in the Beowulfan government]]. Of course, this branch of the family was mentioned earlier, but still...
** Fan-beloved Victor Cachat, of course. From secondary WideEyedIdealist in one short story to main character one story and one book later, [[IncrediblyLamePun this Gunman was probably the fastest to fire]].
** Eloise Pritchart. From relatively minor POV character in ''Honor Among Enemies'' to [[spoiler:President of the Republic of Haven and series anchor in her own right]] in four books or less!
* ''Literature/ThoseThatWake'' has Isabel, who appears early on and shows up again in the middle of the book.
* ''Literature/AFantasyAttraction'' has Aleksandra, a dragon who is collecting for her hoard. She is invited in, and you promptly forget about her. [[spoiler:She shows up later just in time to incinerate a tribe of ogres]].
* In Literature/DangerousSpirits, Niki's father receives a vague reference in passing in Green Fairy. [[spoiler: Turns out it's Konstantine]].
* ''Literature/TheReynardCycle'': In ''Defender of the Crown'', Reynard follows the trail of an assassin to the garden of a herbalist, where he meets with an assistant. [[spoiler: It is later revealed that the herbalist is Hermeline, Reynard's scorned ex-lover, who uses the opportunity to sell Reynard poison rather than a sleeping drug. As a result, Reynard ends up accidentally ''killing the Queen'']].
* Literature/ASongOfIceAndFire has egregious numbers of Gunmen. An outstanding example would be Lord Beric Dondarrion, who was dispatched in the first book to deal with outlaws, only to show up two books later. Almost every important character, if not introduced, was at least mentioned a book prior.
** In [=GoT=], Cersei exiles Ser Barristan from court for political reasons. Several books later, he shows up to save Daenerys's life and pledge his loyalty to her...which leads to him becoming a POV character.
** The Faceless Men are described in passing as a legendary guild of assassins, before the protagonist [[spoiler:Arya]] joins them. Her training with them forms a lot of [[spoiler:Arya]]'s character arc.
** Houses Bolton, Greyjoy, Tyrell, and Martell are all mentioned or given minor introductions early, but gain major plot importance later.
** [[spoiler:Wex Pyke]] appears in "A Clash of King's" in Theon's chapters, [[spoiler:as a mute bastard who is made Theon's squire]] and accompanies him to [[spoiler:Winterfell]]. In "A Dance with Dragons" [[spoiler:it turns out he survived the Sack of Winterfell and has revealed to Lord Manderly the truth of what happened and knows where [[HiddenBackupPrince Rickon Stark]] is hiding.]]
* ''[[Literature/CalLeandros Madhouse]]'' has Seraglio, Robin's housekeeper, who seems to get introduced for the sole purpose of disapproving of Robin's wayward ways and making pancakes. At the end oft the book, though, she turns out to be [[spoiler: the one behind the assassination attempts on Robin]].

* Something of a bizarre usage in Creator/DanAbnett's ''TabletopGame/{{Warhammer 40000}}'' novels, where his early ''Literature/GauntsGhosts'' stories namedrop characters who he would later develop in future novels, but his WordOfGod reveals that he hadn't actually planned so far ahead. For example, comments made regarding Inquisitor Gideon Literature/{{Ravenor}}, who would eventually get his own novels, from the Gaunt's Ghosts Omnibus The Founding:
-->"... first mention of Ravenor (who could have guessed where ''that'' would lead to)...."

* In''Literature/TheWheelOfTime'' every named character in the book will return with greater importance latter on. Every. Last. One. It's even justified by the fact that the three main characters [[spoiler: bend chance, circumstance, and the fabric of the universe itself simply by existing]].

* ''Literature/MidnightsChildren'' has a bunch:
** 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.
** Saleem's uncle Mustapha is so irrelevant for most of the story that Saleem barely even describes him or his children. However, towards the end of the book, [[spoiler:he briefly gives Saleem shelter after the rest of the family is killed. It's also implied that he helped the Widow track down the midnight children]].
** When she's initially introduced, Parvati-the-witch is merely Saleem's most vocal supporter during the Midnight's Children Conference, [[SubvertedTrope but Saleem makes no attempt to hide her later importance]]. Towards the end of the story, she encounters him in the flesh at Bangladesh, and saves his life by smuggling him back into India.
** Mary Pereira. [[spoiler:She runs away after her confession to the Sinais, and Saleem says he doesn't know what happened to her after that, implying she's gone from the story for good. At the very end she's revealed to be the manager of the pickle factory where Saleem works in the present day, who took him under her wing after all his other friends and family were gone.]]
* Early in ''Literature/TheSecretsOfDrearcliffGrangeSchool'' it's mentioned as a passing oddity that a student named Enid ffolliott has been missing for two years but is still called on during the weekly roll-call because she never officially left the school. She makes a dramatic reappearance later in the story.
* In ''[[Literature/FirebirdLackey Firebird]]'', the protagonist Ilya frees a nightingale and a fox who both [[AndroclesLion come back to help him later]].
* In ''Literature/TheWildOnes'', [[SewerGator Gayle]] appears to be another obstacle in Kit's path to prevent him from getting the Bone of Contention. However, he makes a deal with Gayle off-screen and she is never mentioned again during the book. That is, not until she shows up at the end to eat Sixclaw, and to scare all of Titus' army into running away.
* In ''Literature/ShamanBlues'':
** Katia, alluded to as being in Bonn throughout the first half of the story, as well as the object of Witkacy's musings on their AmbiguousSituation together, returns halfway through and comes to Witkacy for help.
** The hospital ghost who clues Witkacy in as to the nature of the wraith comes back to tell him about the [[ArcSymbol spiral]] and what it does to ghosts.
* ''{{Literature/Vampirocracy}}'': [[spoiler: Harold and Elizabeth Anderson, seemingly two inconsequential potential clients of Leon's PI firm, turn out to being the key to finding out who killed several vampires.]]
* ''Literature/JohnDiesAtTheEnd'': Amy turns out to be this. Early on in the novel we find out she went to high school with Dave and is Big Jim's sister, but then she disappears until Book 2. [[spoiler:She returns after Dave and John find out Korrok has been kidnapping her in her sleep. Everything comes back around when Dave begs for her to be saved, which is likely the reason Monster Dave exists in the first place...]]
* In ''Literature/TheSunSword'', Ser Laonis di'Caveras saves Lissa's life in the opening chapters of the book. He turns up for an unnamed cameo appearance at the end of the second book, and then four books later he [[spoiler: saves Diora's life. The same woman who, as a very young child, accused him of being less than a man for initially refusing to save Lissa's life.]]
* ''Literature/{{Edgedancer}}'' (a novella of ''Literature/TheStormlightArchive''):
** Double-subverted with the crazy old man Lift chats with after her first visit in the orphanage. Later, it turns out that Nale's acolytes believe him to be the Lightweaver they're hunting. [[spoiler:Turns out he's not; then it turns out he's actually a [[TheWormThatWalks Dysian Aimian]] who [[MuggingTheMonster kills the acolytes with contemptuous ease]] and gives Lift some crucial information.]]
** Stump, the old woman who's mean to Lift in the orphanage, later turns out to be [[spoiler:the person Nale was looking for.]]
** The guard captain Lift surprises at the start of the story turns out to be important when Nale is visiting witnesses, looking for Lift.
* Iny Lorentz likes this trope quite a lot.
** In the second book of ''Die Wanderhure'' series, there is a grumpy unpleasant woman abandoned by her lover who later disappears from the plot and is practically forgotten. In the middle of book three, she is revealed to be several thousand miles away from Germany, [[RagsToRiches a Tatar khan's favorite wife]] who pretty much saves the day for the heroine.
** In ''Literature/DiePilgerin'', Aymer de Saltilieu makes his first appearance as a minor landlord whose whole task in the plot seems to be a) prove to Tilla that sometimes EvilIsSexy b) save the pilgrims from his bastard of a cousin. The next time he appears in another region of France, mixed up with the local politics, and then he pops up in Spain as a commander in a decisive battle where Sebastian and Starrheim earn their glory as BigDamnHeroes.

** The story opens with Safi explaining in narration that's she's preparing to rob a carriage because she lost all her money in a card game to a guy she nicknamed the Chiseled Cheater. He appears in book two and it turns out he's [[spoiler:a captain of the Hell Bards, on hunt for her.]]
** Ryber, Kullen's girlfriend, pops up a few times in the first book and vanishes for most of the second, only to reappear in the epilogue and [[spoiler:reveal that she knows suspiciously many things about Merik's affliction.]]
** Early on, Iseult mentions that when she ran away from home, she was rescued by a Carawen monk. The same monk appears later, and it turns out she's Merik's aunt and resident MrExposition.

* ''Literature/TalesOfTheMagicLand'':
** The fact that Gingema had owls is mentioned briefly in book one. In book two, the oldest and wisest of them becomes NonHumanSidekick for the new villain and a recurring character for books four through six.
** In book one, Scarecrow tells Ellie that a passing crow taunted him for having no brains, and that's how he came to the idea that brains are the best thing in the world. By book two, the crow too realizes that it was her who inspired the new monarch of the Emerald City, reacquaints herself with him and becomes one of his most trusted advisors. She acts as messenger for the heroes, becomes Minister of Communications (and once serves as regent when Scarecrow is imprisoned), and generally takes the role of TheCynic in the heroic team.
** Ramina the Mouse Queen acts like a minor DeusExMachina, not different from the other good witches, in the first book. But she's the only good witch to make prominent appearances throughout the series, and in books five and six her mice play part in some crucial plot turns.
** The Leapers, nothing but another problem for the heroes to deal with in the first book, turn into a major ChekhovsArmy three books later as Urfin Jus becomes their leader.
** A Winkie mechanic plays a small (though not unimportant) part in the last battle of the second book. Later he becomes a major recurring character and the "Science" side in any MagicVersusScience conflict.
** A less noticeable example, Gurrikap appears in the prologue to book three as the founder of the Magic Land. He appears again in the prologue to book five, and this time it's more important to the backstory. Also his long-abandoned palace becomes the titular plot location in the sixth novel.
* In Lawrence Block's ''The Burglar in the Closet'' Frankie mentions that the late Crystal Sheldrake had three (concurrent) boyfriends, one of whom is a lawyer. Since she does an [[Series/TheTonightShow Ed [=McMahon=]]] impersonation when mentioning this, Bernie decides that said boyfriend must be named John and after he and Jillian realize the difficulty of locating him without a surname they concentrate on the other two boyfriends as suspects. It's eventually revealed that the guilty party is [[spoiler:Crystal's ex-husband's attorney, ''Carson'' Verrill]].
* ''Literature/SmallerAndSmallerCircles'': Councillor Cesar Mariano, who sponsors free dental checkups for street children, is introduced as simply a leader in the local government. Fr. Saenz then notices one of his vans advertising these dental services, and then later figures out that the murder victims, also street children, might have had dental records thanks to Mariano's program.
* ''LightNovel/UndefeatedBahamutChronicle'': Alma Kilzrake, aka [[spoiler:Almatea Atismata]]. She's first mentioned in the very first volume, as [[spoiler:Lisha's younger sister]], and believed to be dead. She makes her first appearance fifteen volumes later and becomes a major character.

** Bellatrix Lestrange is on trial with Crouch Jr. in the PensieveFlashback in ''Goblet of Fire''. By the end of the series she's the most prominent and loyal Death Eater.
** Grindelwald, who was mentioned briefly in the first book in Dumbledore's Chocolate Frog Card description as an evil wizard whom Dumbledore fought. [[spoiler:The last book gives him a lot of backstory, including the revelation the he was once Dumbledore's friend.]]

* In ''Literature/TheHungerGames'', after Katniss shot an arrow at the Gamemakers she said that one of them tripped backwards into a punch bowl. She has a little interaction with him during her pre-Games interview, then he is never mentioned again. Until the next book, ''Catching Fire'', when she formally meets him and finds out that his name is Plutarch Heavensbee and he is now the Head Gamemaker. At the end of ''Catching Fire'', she finds out that he is ''also'' [[spoiler: part of a Capitol rebel group, and helped orchestrate the plan to break the victor-tributes out of the Quartel Quell arena]]. He then becomes a major character in ''Mockingjay'' and a significant player in the [[spoiler: war effort for the rebels]].

-->''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 [[CrowningMomentOfFunny 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 CrowningMomentOfHeartwarming in the whole series.

* ''Literature/TheFourFeathers'' has Abou Fatma. He appears briefly in an early chapter, delivering [[TheRiverWar General Gordon's]] letters to Jack Durrance, in a moment that merely establishes him as an Arab loyal to the British. He doesn't reappear until the very end, when he's revealed to be Harry Faversham's friend and [[spoiler:helps him and Colonel Trench escape from prison]]. In the 2002 film he's given a [[AscendedExtra much larger role]].

* In ''Literature/TheManualOfDetection'', a sleepwalking custodian named Arthur appears to be a BitCharacter. [[spoiler: Turns out he's the overseer of the Agency]].

** Sirius Black, mentioned in passing in the first chapter of the first book and revealed two years later to be the title character of the third book.

** Mundungus Fletcher has been getting small, one-time mentions as early as ''Chamber of Secrets'', only becoming even slightly important to the plot in ''Order of the Phoenix''.

** [[spoiler:Aberforth Dumbledore]] first appears as the barman of the Hog's Head Tavern in ''Order of the Phoenix'', although he isn't mentioned by name. Earlier, Dumbledore does mention him by name in ''Goblet of Fire''.

** Even Neville Longbottom could be considered one of these; even in book one, he has little to do with the overall plot, and he remains a BitCharacter until ''Order of the Phoenix''. In ''Deathly Hallows'' he [[spoiler: cuts the head off of Nagini, the final Horcrux]]. He probably could have been introduced later like Luna was and it wouldn't have made much difference to the plot.

* In Lawrence Block's ''The Burglar in the Closet'' Frankie mentions that the late Crystal Sheldrake had three (concurrent) boyfriends, one of whom is a lawyer. Since she does an [[Series/TheTonightShow Ed [=McMahon=]]] impersonation when mentioning this, Bernie decides that said boyfriend must be named John and after he and Jillian realize the difficulty of locating him without a surname they concentrate on the other two boyfriends as suspects. It's eventually revealed that the guilty party is [[spoiler: Crystal's ex-husband's attorney, ''Carson'' Verrill]].

** Similarly, both Herald Lavan Firestarter (''Brightly Burning'') and Herald Vanyel (''The Last Herald-Mage'') are mentioned as historical personages long before MercedesLackey wrote a book/trilogy about them.

* In ''Literature/{{Edgedancer}}'':
** Double-subverted with the crazy old man Lift chats with after her first visit in the orphanage. Later, it turns out that Nale's acolytes believe him to be the Lightweaver they're hunting. [[spoiler:Turns out he's not; then it turns out he's actually a Sleepless who gives Lift some crucial information.]]

** A Winkie mechanic plays a small (though not unimportant) part in the last battle of the second book. Later he becomes a major recurring character and the embodiment of MagicAndScience marching together.

** In the second book of ''Die Wanderhure'' series, there is a grumpy unpleasant woman abandoned by her lover who later disappears from the plot and is practically forgotten. In the middle of book three, she is revealed to be several thousand miles away from Germany, [[FromRagsToRiches a Tatar khan's favorite wife]] who pretty much saves the day for the heroine.

* A particularly impressive one from Creator/DavidEddings. In ''The Ruby Knight'', the second book of his ''[[Literature/TheElenium Elenium]]'' trilogy, Zalasta is introduced in what is practically a throwaway scene; literally, he's seen for less than a page. He's not seen or mentioned again in the entire trilogy... and then he shows up in the ''Tamuli'' trilogy as one of the major characters, [[spoiler: and ultimately turns out to be the closest thing to a BigBad for ''both'' trilogies]].

* In ''Literature/TheSilmarillion'', Lúthien Tinúviel is introduced off-hand by Tolkien simply as the daughter of Thingol and Melian, but later, as we all know, plays a major part in [[spoiler:retrieving a Silmaril]] by owning Sauron's face and tricking Morgoth himself and proving herself to be totally {{Badass}}.

* In ''Literature/TheSunSword'', Ser Laonis di'Caveras saves Lissa's life in the opening chapters of the book. [[spoiler:He gets an unnamed cameo appearance in the next book, and then in the last book he saves Diora's life.]]