Continuity Creep

"Sam: Remember when we used to just... hunt Wendigos? How simple things were?

Dean: Not really."

- Supernatural

Continuity Creep is the tendency of a TV show or comic book that starts off with an episodic Sitcom, Adventure Town or Monster of the Week format, which then begins to accumulate more and more Continuity Nods and ongoing storylines. Or if it starts off with each episode containing a single self-contained story, and ends up with sprawling plots that span multiple episodes, it has undergone continuity creep.

In a comedy show, this trope is often a symptom of Cerebus Syndrome, but it can occur independently. In a dramatic or action-adventure show, it's often a sign of Growing the Beard. Arc Welding is this trope applied retroactively. "Too much" may result in Continuity Porn. See also Kudzu Plot, when instead of a series sprouting references to past events, it sprouts open-ended mysteries for use in future events. Often more noticeable in a Long Runner. Generally averts Aesop Amnesia and Status Quo Is God.

Anime & Manga

 * Witch Hunter Robin starts off as a fairly dull Monster of the Week affair; however, about halfway through, it suddenly develops an ongoing plot.
 * Same with The Big O.
 * The Yu-Gi-Oh!! manga was about Yugi playing a Game of Shadows in every chapter until the author switched focus to the card game, at which point it gained an actual overarching plot.
 * Hayate the Combat Butler has a plot involving Athena, Mikado Sanzenin and Nagi's mother, the pendants, and Wataru's mother.
 * Bleach did something similar to this for a while. For the first dozen or so chapters, it was pretty much a light horror-comedy with "Hollow of the week" stories and some of Ichigo's friends getting attacked or empowered every so often, before becoming a straight action saga.
 * The World God Only Knows started off as a Girl of the Week story with Keima making a different conquest in each arc. After awhile, some of the girls become recurring characters, and once the Goddess arc begins, a few of the previous girls become major characters.
 * Rurouni Kenshin was about Kenshin having sword fights and such in the Meiji era.
 * Trigun began as a progression through a series of Adventure Towns before the Myth Arc (only barely hinted at previously) kicked in around halfway through.

Comics
"But in the course of these throwaway "stories"... He says I developed a, quote, "personality"... and a boyfriend... and a nice set of body-image issues, thank you very much... and, well, voila... this goofy mess somehow wound up morphing into a, quote, "real comic". A "real comic" in which, you'll notice, I still seem to get tied up a lot. That's not my idea of a "real comic", but whatevs."
 * Jhonen Vasquez does this quite a bit.
 * Johnny the Homicidal Maniac began as a series of random, one-off strips. After a while, the comic evolved so that each issue told a longer story, and a full-fledged Myth Arc was in place by the end. This was deliberate.
 * Squee! was intended as a return to one-off silliness, but ended up with an ongoing plot in the end.
 * The comic version of Sabrina the Teenage Witch started with one-off stories because Tania del Rio (the writer) had orders from her editor to do the stories Archie style. However, she slipped in some continuity slowly over each issue. By the time she got a new editor (who also happens to run the Sonic the Hedgehog comic), the "Four Blades" plot was already underway.
 * Lampshaded in the between the chapter meta panels in Empowered.


 * In Neil Gaiman's The Sandman, this is intentional from the start, but it's still rather odd to find out that a small event from the fourth comic ends up being important for the climax of the series.
 * Garth Ennis's run in The Punisher. The CIA's disastrous attempts to recruit him in "In The Beginning" is brought up in "Mother Russia," and a couple of characters have very important roles in "Up is Down and Black is White", "Man of Stone" and "Long Cold Dark". Yorkie from "Kitchen Irish" crops up again in "Man of Stone" and "Long Cold Dark". "Mother Russia" is a crucial part of later stories "Up is Down and Black is White", "Man of Stone", "Long Cold Dark" and "Valley Forge Valley Forge." The events of "The Slavers" has a bearing on "Widowmaker."
 * DC and Marvel superheroes can be considered this in general. Back in the Silver Age, every story was a self-contained plot. Over the years, comics added more and more continuity until the modern soap-opera style of storytelling resulted.

Fan Works

 * The online video series Marvel/DC After Hours (AKA I'm a Marvel And I'm a DC) started out as a simple parody of the "Buy a Mac" ads with Spider-Man and Superman discussing the relatively sorry state of movies based on DC characters compared to Marvel's. Gradually more characters were introduced until it completely morphed into a story-driven and occasionally quite moving piece of work, all while keeping the comic-based humor intact as various characters continue to praise or lament their latest films.

Literature

 * This is true to a certain extent in The Dresden Files. The first few books introduce us to the various factions and old friends of Harry whom we've never met before; but it gets to the point that they can play off each other, and you can have complex stories with multiple enemy factions each seeking something and getting in each other's way.
 * The first two Harry Potter books were basically standalones. The third one seemed to follow this, but then at the end, forming a Sequel Hook. From that point on, each book followed an ongoing Story Arc which only concluded with the end of the series.
 * But the books were planned as a seven-book arc from the beginning, which meant that many events in the first two books integrated seamlessly into the overall Myth Arc (the biggest one being Tom Riddle's Diary was actually.
 * The first two books being almost stand-alones are more because not enough of the background had been established for the over-arching plot Rowling had intended from the beginning. It wasn't until Prizoner of Azkaban that enough had happened that the plot that had been developing since chapter one of The Philosopher's Stone could show itself.
 * The first few books of A Series of Unfortunate Events were narratively and geographically discrete, and had only a handful of recurring characters; then The Austere Academy introduced the Quagmires and VFD and sent everything in a significantly more arcish direction.
 * The first few books were later retconned into the story arc by the Unauthorized Autobiography.
 * Discworld. In the first few books, Ankh-Morpork was a generic fantasy city that Terry Pratchett could burn down for the sake of a gag, and Bad Ass was "a village in the Ramtops" with no suggestion of any further society. Now it's impossible to set a book in Ankh without worrying about the Watch, the Times, the wizards and CMOT Dibbler, and the Kingdom of Lancre is just as narratively dense, if still more sparsely populated.
 * The wizards are a specific example. In the early books the UU had a different Archchancellor every time we visited, and the faculty were just whatever random characters the plot required (and the Librarian). Then he introduced Ridcully, and with him the Bursar, the Dean, the Senior Wrangler, the Lecturer in Recent Runes, and Ponder Stibbons. Paradoxically, this stability means that the UU has changed more in the later books, since it's got a fixed point to develop from.
 * A (common) moment of genius on the part of Pratchett though - in the earlier books the wizards all had names, and consequently died. Then he introduced the usual suspects, didn't give them names, and they became recurring characters. The only exceptions - Ponder Stibbons (Who's too smart and cowardly to die), Ridcully (Who's too stubborn to die) and Rincewind (Who's too fast to die, and in any case isn't so much a wizard as a wizzard) all, in some way, behave very differently from the standard Discworld wizards.
 * The Vlad Taltosh novels, set in Dragaera, were originally supposed to be able to stand alone, and aren't written in chronological order. Author Steven Brust admitted that this becomes less realistic as he continues to develop the series.

Live Action TV

 * Stargate SG-1 has generally gone for a Half Arc Season format, but as it went on, the arc episodes became more numerous, and the standalone episodes got rarer and rarer. The Anubis arc was a particularly notable example, as it lasted for two entire seasons.
 * Friends started off as a series of one-off episodes that didn't really affect each other. As it went on, continuity became more important, partly with Monica and Chandler's evolving relationship but especially Ross and Rachel's.
 * Boy Meets World went through a similar evolution.
 * As Buffy the Vampire Slayer went on, the Monster of the Week episodes gradually became fewer in number in favour of episodes dealing more directly with the Big Bad, to the point where the last season contains essentially no standalone episodes at all (with the possible exception of "Beneath You" or "Him")
 * And every single episode of season 5  turned out to be story-crucial for the big finale of the season.
 * Its spinoff Angel went through the same evolution, ultimately having a giant epic storyline that lasted 3 seasons(!). Angel then proceeded to devolve back into the much lighter monster of the week episodes in season 5 (including one which turned Angel into a puppet), before going back to an overreaching storyline about half way through.
 * Star Trek: Deep Space Nine had this happen progressively over its run, starting out with mostly standalone episodes with a few arcs in the background and getting more and more serialized over time.
 * Star Trek: Enterprise had this happen too, but more suddenly: its almost completely standalone format was abruptly changed to a serialized year-long story arc for its third season. The fourth season dialed it back down to Half Arc Season levels, but at the same time kept the serial nature of the show by making most of the standalone stories into two- or three-episode "mini-arcs".
 * Reaper started off as a Soul of the Week show, but about halfway through season one it started with the demon rebellion arc and examining the thorny questions of who Sam's dad is . Simultaneously Growing the Beard and developing Cerebus Syndrome.
 * The X-Files started off with a Monster of the Week format, but gradually built up a myth arc starting in season 2 with a three-part episode about Scully being abducted.
 * The myth arc was there from the beginning. A quarter of the episodes in the first season, including the pilot, were part of it.
 * Farscape fits this trope perfectly, as nearly the entire first season was a series of stand-alone, Fish Out of Water stories focusing on John fitting in with the crew with an extremely loose over-arching story that almost never came into play. This changed drastically in Nerve the 19th episode, which introduced Scorpius and got the actual story moving. The continuity began to creep in more and more in Season 2 and eventually took over in Season 3 where pretty much every episode helped forward the overall story. Sadly, this ended up being the death of Farscape as the show developed Continuity Lock Out and failed to bring in any new viewers between Seasons 3 and 4, causing the network to cancel them.
 * Doctor Who began as a series of isolated stories set in various Adventure Towns in time and space. (The characters, however, did evolve throughout the season.) However, the second season saw its first major reference to the past in the form of the return of the Daleks, after they had all died, with the Hand Wave explanation that this adventure took place before their destruction. This and future seasons saw an increasing number of recurring elements and characters. It wasn't until the seventies that the narratives started to become definitely interconnected, and in the eighties this turned into Continuity Lock Out and Continuity Porn. The new series, while still containing series and multi-series long arcs (with a few stand-alones) has dialed back on the Continuity Lock Out, if not completely.
 * Power Rangers began as a very episodic show, with the only continuing plot of note in the first season being the Green Ranger arcs. Season 6, Power Rangers in Space, brought the Continuity Creep in alongside a year-long Crisis Crossover. Every season of the show since then, while self-contained and having brand new casts yearly, continues to focus on hefty plots.
 * It really started earlier, right around season 3, which featured very few standalone episodes, almost every plot being multi-parters that each also connect into overarching plots. For example, in the arc that introduced Katherine, she helps Rita and Zedd capture Ninjor, the Falconzord, and Kimberly's pink power coin. While the power coin plot was resolved by the end of that arc, the other two aren't resolved until the later "Master Vile and the Metallic Armor arc. And one stand-alone after that, the season saw the Alien Rangers arc, which helped to really shake things up.
 * The Pretender did start out teasing some over-arching mysteries (Jarod's origins and who killed Miss Parker's mother), but early episodes were largely episodic - focusing on Jarod's pretends and Miss Parker's pursuit. By Season 2, these and newer storylines started to gain prominence alongside the existing formula. By the last season, most episodes featured something that would be relevant to another or hint at something larger in store for viewers.
 * The Sarah Connor Chronicles, starting about halfway through its second season, when it starts to transition away from Terminator of the Week format.
 * Supernatural was originally supposed to be about various monsters and urban legends made real, with just enough backstory to explain why the Winchesters kept getting involved. But the show's (largely female) fanbase decided they liked seeing the gorgeous boys' angst, so more and more Myth Arc elements were added, to the point that filler episodes can seem very out of place. (Lucifer's loose on Earth? Eh, we can still take some time to banish this ghost.)
 * Journeyman was headed this way before it was axed.
 * Chuck started off as a Monster of the Week show, but then introduced Fulcrum as the season enemy in the second season. This trope really kicked in during the last third of the second season and has kept up since then.
 * Despite its roots as a spinoff of Dallas, Knots Landing's first season was largely episodic, with more of a family/neighborhood drama than a soap. In fact the first season of Dallas was episodic, as well.

Video Games

 * The first The Legend of Zelda game had so little of a connecting storyline, that most fans thought it was just the same story, retold over and over and over (a misconception still held by some today). Then came The Legend of Zelda Ocarina of Time, which had an implicit connection to The Legend of Zelda a Link To T He Pasts Imprisoning War (later confirmed in the 25th anniversary encyclopedia Hyrule Historia to be the result of one of three possible aftermaths of Ocarinas story where Link dies). Wind Waker also had a direct connection to Ocarina, the first game to explicitly confirm a timeline with more than one Link, with two sequels, Phantom Hourglass and Spirit Tracks clearly following this story too. Twilight Princess, though mostly only seen through hints in-story, was confirmed by Word of God and Hyrule Historia to follow the "child" Alternate Timeline at the end of Ocarina (a different one to the one Link to the Past follows).
 * Sonic the Hedgehog: The games went from being almost completely separated to being connected all over the place to point where it no longer makes sense sometimes.
 * The Mega Man series almost never has a storyline to speak of. The Mega Man X series, especially later on, tend to have self-contained plots with a Continuity Nod here and there and Character Development. The Mega Man Zero series quite clearly continue one from the other, with major references to the previous games, the series' own convoluted backstory, a couple to the X series and a nod or two to points from the Classic series. Between the two Mega Man ZX games there's a pretty significant Time Skip, but both games are also heavy on nods to all the past series. Mega Man Battle Network and Mega Man Star Force, being RPGs, naturally are more story-heavy to begin with.
 * The Tomb Raider series initially had little or no connection between the games, but since Crystal Dynamics took over things have gotten more unified and focused.
 * Touhou Project. The first few games had basically no continuity, to the point that no one is entirely certain whether the sixth is a Continuity Reboot or not. The next few included characters from and references to earlier games, but it still didn't amount to much. Then we got some serious attempts at world building around the time of the tenth game, and the plots of the games have been increasingly linked since.

Web Comics
"Continuity tends to grow as works of fiction mature and get more of a history behind them.
 * Order of the Stick started off with a simple story about a group of adventurers seeking an evil baddie to defeat. It has since branched off into multiple long-running, complex storylines to the extent that individual strips are all but incomprehensible unless one reads the whole archive. This has had several lampshades hung on it.
 * Ctrl+Alt+Del began as a gag-a-day strip, but soon developed into a series of multi-month-long stories divided by one-off gags.
 * Honestly, this trope describes whatever the hell happened with Bob and George about a thousand times better than Cerebus Syndrome.
 * Sort of example: Minus was usually standalone strips that occasionally had pieces stretching over multiple strips. However this strip started a series of events that and went on for 25 strips until the end of the entire comic!
 * Unicorn Jelly started as a simple, cute fantasy tale of a witch and the transgendered blob who loved her. It has hit major Cerebus Syndrome, and spawned not just a universe with its own well-defined but very alien physics and Bizarre Alien Biology, but a Multiverse of Alternate Continuity and several spinoffs.
 * Starting well before most webcomics did, Sluggy Freelance could be the Ur Example.
 * It has some stories that last months. And a collection of looser storylines that run parallel to each other, alternating from the sidelines to the foreground but never completely ending, for   years.  And this is talking about a webcomic that updates daily with barely a single interruption. The Archive Panic is heart attack-inducing.
 * Dresden Codak and the Hob storyline.
 * The first three story arcs of The Inexplicable Adventures of Bob (that is, the first three years' worth of stories from the strip's heyday as a weekly printed strip at Penn State) have negligible continuity with each other. It's only in the fourth story arc that the various threads start intermingling into an elaborate world full of space empires, dragons, and artificial life forms.
 * Irregular Webcomic originally had unrelated gags in each theme, then an ongoing story in each theme, and is eventually had a massive ongoing story involving almost every theme. Mentioned in the rerun commentary:

Maybe I should start a new webcomic which begins with a rich story-based tapestry with a detailed background, and then devolves into disconnected gags with no ongoing story or continuity."

Web Original

 * According to Word of God, the Whateley Universe started out like this. Six authors writing inter-related short stories about their characters. It evolved into over a dozen Canon authors and ongoing arcs.
 * Ostensibly, one of the reasons Rooster Teeth ended Red vs. Blue: The Blood Gulch Chronicles at Episode 100 was to put an end to the Continuity Creep and continue writing for the series from a point where newcomers could enjoy the show without Continuity Lock Out. While they succeeded, the series from that point forth became much more plot based, and a good number of the Call Backs still require familiarity with all the older episodes (as opposed to just episodes from the most recent trilogy, Recollection).
 * The Slender Man Mythos initially just consisted of a few blogs and YouTube series that were all independent of each other as far as continuity went. The only links were Slender Man's appearance and his attributes, and even the latter tended to be somewhat subjective. But with the accumulated references to previously made blogs and the development of the Core Theory, the continuity of the Mythos now is quite impressive. Newcomers may actually feel overwhelmed by how much they have to keep up with.
 * SCP Foundation started off just with pages on the various, isolated SCPs, but the site has developed stronger continuity thanks to stories about the Foundation members themselves and, especially, thanks to later SCPs being used, collected and/or produced by various anti-Foundation organizations such as the cult of the Serpent's Hand, rich people club Marshall, Carter, and Dark Ltd., and Alternate Universe institute Alexylva University.

Western Animation

 * Invader Zim became more and more self-referential after the episode "Tak, the Hideous New Girl" (especially since at the end which he would later try to continually replace). If it wasn't cancelled, it would have developed a Myth Arc about Operation Impending Doom 2 failing at the hands of the Resisty, and the story would have culminated in a movie.
 * Justice League initially had two- and three-part episodes which didn't really affect each other (except for the recurring villains). Then they started throwing in short arcs that built on the plot of previous DCAU series, such as the season two premiere, which was basically a follow-up to Superman: The Animated Series's finale. And then, even the completely standalone episodes would still have brief moments suggesting continuity: the slow buildup of UST between John Stewart and Hawkgirl, and the very subtle bits of foreshadowing pointing towards the season two Grand Finale. Then Justice League Unlimited went all-out and used overarching plots that took half the season to resolve--CADMUS in the first two seasons, then the Secret Society in season three. It's generally agreed that the growth in continuity was concurrent with an upswing in quality.
 * Code Lyoko, once enough episodes were in circulation for viewers to know what the hell was going on. It actually started with an unexplained One We Prepared Earlier opening.
 * Transformers continuity became substantially stronger after the animated movie. Headmasters continued this trend with episodes that, while for the most part self-contained, were intended to be shown in a particular order. Masterforce then had a full-on Myth Arc.
 * Beast Wars started out episodic, but after the first season final it developed continuous Story Arcs.
 * Transformers Animated began with almost entirely self-contained episode, and while it has yet to get a continuous Story Arc, more and more episodes became continuations of previous ones. Story editor Marty Isenberg says this is his preferred form of writing.
 * The Venture Brothers started off random adventures parodying Johnny Quest by Season II it all became interlocking and connecting stories, some of which purposely aired out of order.
 * Daria was completely episodic in its first three seasons, with only an occasional Continuity Nod. Then the season three finale saw Jane get a steady boyfriend, and the remaining two seasons and two movies turned into an occasionally quite moving examination of this change to the status quo as well as Quinn showing some Hidden Depths.
 * The Fairly Odd Parents did this in later seasons, when they had enough previous material to do so. One of the antagonists or one of Timmy's previous wishes gone wrong returns for revenge on occasion. This is especially prevelant in the episode concerning Unwish Island.
 * If the first few episodes of the third season are any indication, Phineas and Ferb has finally become a show all about referencing itself.
 * Re Boot was episodic until ABC canceled it. The move to another network allowed the writing staff far more freedom, and this trope followed suit.
 * Adventure Time starts going in this direction after second season finale, which gave the series a good case of Cerebus Syndrome.