History Main / ArcWelding

* ''Franchise/MarvelCinematicUniverse'':
** The later Phase One films dealt with an object of power called the Tesseract and TheStinger to ''Film/TheAvengers2012'' revealed that Thanos was that film's GreaterScopeVillain. TheStinger of ''Film/ThorTheDarkWorld'' would then tie those two together with its own MacGuffin, the Aether, when it stated that the Tesseract and the Aether are both [=MCU=] versions of [[ComicBook/TheInfinityGauntlet Infinity Stones]], which Thanos has historically been involved with in the comics.
** In a smaller instance, in the first ''Film/IronMan1'' movie we are told that Howard and Maria Stark died in an accident when Tony was younger. Not much thought is given to this since unfortunately, car accidents are a common occurrence in real life. Then, years later during ''Film/CaptainAmericaTheWinterSoldier'', we find out via FreezeFrameBonus that [[spoiler:the accident was deliberately caused after the Starks were targeted for assassination by HYDRA]]. ''Film/CaptainAmericaCivilWar'' follows up on this by confirming that [[spoiler:not only did HYDRA order the assassination, but Bucky was the one to carry it out, savagely beating the Starks to death]].

* ''Series/AgentsOfSHIELD'':
** Various, seemingly independent threats throughout Season 1, such as Project Centipede and [[CorruptCorporateExecutive Ian Quinn's]] corporation, are eventually be revealed to all be orchestrated by the same BigBad, [[HiddenVillain the Clairvoyant]] [[spoiler: who turns out to be a HYDRA agent, tying into the events of ''Film/CaptainAmericaTheWinterSoldier''.]]
** One of Season 2's initial main villains, "[[DeadlyDoctor the Doctor]]" [[spoiler: (Calvin Johnson, aka Cal Zabo, aka the comics Mr. Hyde)]] is revealed in the second half of the season to have been working on ([[LoveMakesYouEvil as he perceived it]]) the behalf of [[spoiler: his wife, Jiaying]], who eventually serves as the season's FinalBoss. She, in turn, can blame her StartOfDarkness on [[MadScientist Daniel Whitehall]], the other of the first half of the season's main villains. So, in this way, most of the season's main villains were all connected to each other.

* ''Series/{{Arrow}}'': The first episode of the second season features a group of copycat vigilantes, who, among other things, kill Starling City's mayor. The midseason finale reveals that they were organized by [[DarkMessiah Brother Blood]] [[spoiler: and [[TheManBehindTheMan Slade]]]], in order to give [[VillainWithGoodPublicity Blood]] the opening he needs to run for mayor.
** Each season also finds a way to tie together its Present Day and Flashback storylines:
*** Season 1 revealed that [[BigBad Malcolm Merlyn]] was responsible for the shipwreck that stranded Oliver on the island to begin with.
*** Season 2's storylines are connected by [[PsychoSerum Mirakuru]]. It was his search for it that led [[EvilutionaryBiologist Dr. Ivo]] to the island in the flashbacks, it's being used as part of Brother Blood's plans in the present, [[spoiler: and it's responsible for Slade's FaceHeelTurn in the flashbacks that leads to him being BigBad in the present]].
*** Season 3's storylines are loosely connected by the presence of Maseo, who was Oliver's ARGUS handler in Hong Kong before his son's death by the Alpha/Omega virus led to him joining the League of Assassins, becoming TheDragon to Ra's Al Ghul in the present. The final episodes tie the storylines more tightly together, however, as [[spoiler: Ra's gets his hands on Alpha/Omega and intends to destroy Starling City with it.]]
*** Season 4's storylines also share only vague connections with each other -- the organization Oliver is sent to infiltrate in the flashbacks is Shadowspire, who serve as VillainOfTheWeek in one episode's present setting and served as part of [[spoiler: Andy Diggle]]'s StartOfDarkness. Also, the [[MacGuffin magic idol]] that flashback villain Baron Reiter is after also serves as [[BigBad Damien Darhk's]] power source in the present.
*** Season 5's storylines have yet another vague connection in that the flashbacks have Oliver being mentored by Talia Al-Ghul, who in the present in now working with new BigBad Prometheus.
** Late in Season 3, Ra's Al Ghul reveals the existence of his rival, Damien Darhk, the leader of H.I.V.E., and that he was responsible for various episodic threats that Team Arrow had faced in Seasons 2 and 3. This on top of H.I.V.E. being responsible for Deadshot becoming a mercenary and the death of Diggle's brother.

* ''Series/TheDefenders2017'' bridges together the two different plot lines involving [[AncientConspiracy the Hand]] introduced in previous series. In ''Series/{{Daredevil|2015}}'', they're established as being in a SecretWar with [[AncientTradition the Chaste]], while in ''Series/IronFist2017'', they're stated to be ancient enemies of [[HiddenElfVillage K'un L'un]]. Here it's revealed that the Hand was founded by exiles from K'un L'un, and the Chaste was created afterwards to serve as the Iron Fist's army to fight them in defense of the city.

* ''Series/Supergirl2015'': The episode "The House of L" ties together two of Season 4's major storylines, as [[spoiler: Lex Luthor]] is revealed to have helped Ben Lockwood set up the Children of Liberty as [[UnwittingPawn patsies]] for his larger plan, and has also been helping [[{{Ruritania}} Kaznia]] train the Supergirl clone known as Red Daughter.

* Interviews with the creative team behind ''WesternAnimation/JusticeLeague Unlimited'' and their remarks in various DVD audio commentaries reveal that they were several episodes into the production of ''Unlimited'' before they realized that they were working toward what became the "Cadmus Arc." The majority of the arc expanded upon and revolved around the events of "A Better World," an episode from season two of ''Justice League'' which had been written with no thought to an ongoing story. Cadmus turns out to have been responsible for two previously encountered (groups of) villain, Doomsday and the (Joker's) Royal Flush Gang. The ultimate reveal of the BigBad, Brainiac, actually connected back to an episode of ''WesternAnimation/SupermanTheAnimatedSeries'', which had been produced eight years and two TV series before the current series was even conceived. There were also throw-away lines and references that connected to as far back as "On Leather Wings", an episode of ''WesternAnimation/BatmanTheAnimatedSeries'' that was the ''very first'' entry in the Franchise/DCAnimatedUniverse, and even some {{Call Forward}}s to the chronologically-last, ''WesternAnimation/BatmanBeyond''.

* ''WesternAnimation/WhatIf2021'', like its comic book inspiration, is an anthology series, with each episode seemingly being a standalone affair and the only constant is narrator Uatu the Watcher. Then the otherwise-lighthearted Episode 7 has a cliffhanger [[spoiler:with the invasion of an army of Ultron Drones, with Ultron Prime now in possession of all the Infinity Stones. The next episode sees the Watcher focusing his attention on the reality where this originated, but with the Infinity Stones, Ultron was able to sense the Watcher, and with it, learns about TheMultiverse. The situation got so dire that Uatu decides to break his AlienNonInterferenceClause and calls on the heroes of the previous episodes in order to help end the threat.]]

* For almost 20 years, ''[[VideoGame/SonicTheHedgehogCD Sonic CD]]'' was a GaidenGame with no set place in the series' timeline. (Due to the lack of Tails or Super Sonic and the fact it was meant to be ''[[VideoGame/SonicTheHedgehog2 Sonic 2]]'', most fans just assumed it was a prequel.) However, as of the new remake for Platform/XboxLive, Platform/{{PlayStation Network}}, and iPhones, features were added suggesting (and WordOfGod asserted) that it actually occurred sometime before ''[[VideoGame/SonicTheHedgehog4 Sonic 4]]'', and it's specifically tied to ''Episode II''.