You ALL Share My Story

"We are all connected" isn't just hippie-dippie jargon; in Fictionland it's a universal constant like gravity, electromagnetism, and the weak and strong nuclear forces. In a narrative with Loads and Loads of Characters (or even as few as two), these will invariably be drawn together no matter how far away or distinct the characters and their troubles are. They probably won't stick together as strongly as the Character-Magnetic Team, but what ends up happening is that everyone meets at least once and they build at least a working relationship. Essentially, every character works on a different aspect of the plot; while one tracks down the mysterious Woman in White, another fights the left handed killer after her, and a third is trying to find out where the killer gets his orders from.

This can culminate in Season Finales where the characters (either by their own plans or serendipity) come together to beat the Big Bad. Otherwise, expect to see a lot of Right Hand Versus Left Hand struggles as the decentralized cast often struggles against each other as with the villains.

The series might justify this with these characters having an interwoven "fate", or their alikeness (super powers, being supernaturals, street fighters, card duelists or what have you) naturally draw them to each other. Now, if it turns out they're all significant to each other before the story starts, you're looking at One Degree of Separation. If they all stick together after meeting, then they form a Character-Magnetic Team. Related to the Law of Conservation of Detail, in that if they weren't part of the story the author wanted to tell, they wouldn't have been included in the work. Sometimes occurs because Everyone Is Related, other times everyone shared a Mass Super-Empowering Event. See also Hyperlink Story and Debut Queue.

Compare Fate Drives Us Together.

Anime and Manga

 * In Durarara!!, you soon realize that literally EVERYONE is connected, from the Ordinary High School Student Mikado to the Shrinking Violet Anri to her Stalker with a Crush teacher Nasujima to Knife Nut Haruna to Intrepid Reporter Niekawa to The Fair Folk Celty to the Mister Exposition Shinra to Manipulative Bastard Izaya to the amazingly Improbable Weapon User Shizuo to the Frozen Face Kasuka to Idol Singer Ruri to the Butt Monkey fanboy Togusa to the Torture Technician otakus Walker and Erica the Perpetual Frowner Kadota to the Scary Black Man Simon to the Large Ham Kida to A Love to Dismember Seiji to Insane Troll Logic practitioner Namie to... well... everyone. Someone should make a chart about this.
 * Slightly out of date, but done.
 * More complete chart.
 * In Chobits
 * In Ranma ½ there certainly are times when Ryoga clearly arrives in Nerima by accident. However, there are definitely other times when he appears at a coincidentally perfect time to take part in the adventure. I particularly refer you to his appearance in the cave special. Ukyo has about ten seconds to find a guy to go in with other than Ranma, cue Ryoga entering in that exact time span.
 * The cast of GetBackers is an assortment of freelancers who retrieve things, transport things, find things out, etc. for a living, plus some of their friends and enemies. Most storylines involve the GetBackers themselves, Ban and Ginji, taking a job and coincidentally running into at least two other main characters (fellow retriever Shido, information-seeker Kazuki, transporters Himiko and Akabane), plus any other sidekick, friend or associate that might accompany them (third transporter Maguruma, Kazuki's friends Juubei and Toshiki, Shido's friend Emishi). The vast majority of these characters have met at least once, on a particularly dangerous job to retrieve a component of a nuclear bomb or the job to rescue Shido's girlfriend. Maybe half of them are former members of Ginji's street gang, Volts, and all of the main six, plus current New Volts leader Makubex, have some kind of link to the series' Myth Arc.
 * Madlax has several storylines gradually converging into one by episode 18 or so.
 * Baccano!.

Comic Books

 * Grant Morrison plays with this in his Seven Soldiers: Each of the titular seven protagonists' stories brings them against the same foe, even though the characters themselves never meet.

Film

 * Repo Man. "There's this lattice of coincidence, see?"
 * Star Wars. Oh, Star Wars...
 * If you're not a Jedi, a Jedi's close friend, or take orders from a Jedi, you're welcome to live a normal, unremarkable life. If you are one of those things, you will be dragged into an intergalactic war with the Sith. Eventually you will be packed into a small area for the final bit of Rising Action before the Climactic Fight Scene with every other named character who fits this description. This will play out the same way regardless of any qualifications any of you may or may not have about fighting evil robots and space ninjas. The only thing more powerful than the Force in a galaxy far, far away is coincidence. (Although considering that The Force flows through everything, they may be one and the same.)
 * Lampshaded in Star Trek, with Spock's mention of the "Hands of fate" that led the Enterprise crew to completion.
 * Love Actually is all about this trope, culminating in most of the characters going to the local school play.
 * Valentine's Day had this as their main gimmick, but it manages to play off as a bit more realistic than at first glance, due to not all "connections" being particularly plot important or advertised.
 * In What's Up, Doc?, all of the owners of the four handbags, plus their various friends, associates, and loved ones, find themselves staying at exactly the same hotel. This leads to what is possibly the best chase scene in cinema history.
 * In Final Destination 2, five of the characters realise that they have previously cheated death by accident, and each case was the result of one of the deaths in the first film - the reason why they have been targeted this time.
 * In Transformers, the three separate subplots involving Lennox's team, the NSA hackers, and Sam and Mikaela (as well as the main plot about, y'know, the giant robots) all converge when everyone is assembled at the Hoover Dam for the final battle.

Literature
"Reality is a quality that things possess in the same way they possess, say, weight. Some people are more real than others, for example. It has been estimated that there are only 500 real people on any given planet, which is why they keep unexpectedly running into one another all the time."
 * Stephen King - The Stand
 * Effectively averted by Harry Turtledove in his series.
 * Lampshaded and played straight during Robert Jordan's The Wheel of Time: Rand al'Thor tends to bring in other ta'veren around him just by existing.
 * To elaborate, "ta'veren" is the in-world term for people around whom destiny works. Destiny exists in the world, but so do free will and random chance, and the way it's possible for all three to be real is that destiny doesn't actively push anything around unless a ta'veren is nearby, at which point people will make crazily impulsive major decisions out of the blue and freakishly lucky (or unlucky) flukes of chance will happen regularly. Three of the main characters are ta'veren. The book begins in their home village, along with two of their peers (special in another way) and a visiting magic-user. Those six people get broken up partway through the first book and reunited near the end in a justified way (the magic-user was looking for the rest), then broken up again early in the second book and reunited in a very You ALL Share My Story way at the end of the third. Only two of them at most have been together at any time since early in the fourth book. It's now on book 12 and there are hundreds of characters, most of whom have met two or three of the main characters even if they don't know it.
 * Some of the characters in the Ender series
 * Charles Dickens loves this trope. Bleak House is the crowning example: there are over eighty characters, all of whom turn out to be essential to the denouement. Oliver Twist, Little Dorrit, etc. also heavily participate in this structure.
 * Terry Pratchett, author of the Discworld series, lampshades this in Moving Pictures:

"It is a small world.You don’t have to live in it particularly long to learn that for yourself. There is a theory that in the whole world there are only 500 real people--the cast, as it were. All the rest of the people, the theory suggests, are extras. And what is more, they all know each other. And it’s true. Or true as far as it goes. In reality the world is made of thousands upon thousands groups of about 500 people, all of whom will spend their lives bumping into each other, trying to avoid each other, and discovering each other in the same unlikely teashop in Vancouver. There is an unavoidability to this process. It is not even a coincidence. It’s just the way the world works, with no regard for individuals or for propriety."
 * His friend Neil Gaiman elaborated on this in Anansi Boys:


 * It's a major tenet of the fictional religion Bokononism in Cat's Cradle, called a karass. Lampshaded by the narrator at one point when a near-stranger shows him a collection of photos; he reflects later that they were all part of his karass,.
 * Effectively averted (so far) in George RR Martin's A Song of Ice and Fire - there will often be two or more viewpoint characters sharing a few scenes (particularly at major gatherings like weddings and tournaments), but characters wander away from one another just as often as they meet up, and there hasn't yet been a single gathering of all (or even most) if the main characters.
 * Didn't the opening chapters of Game of Thrones have pretty much every POV character (in that book) except Dany in Winterfell?
 * Justified, since they were all related by blood or marriage to Eddard Stark or Robert Baratheon, who in turn were old friends and fought together during Robert's ascension. Also, a fair portion (Jon, Bran, Arya, Sansa) are still children and would be expected to be living with their parents. While they might all have been conspicuously in the same place, at least there are reasons for it.
 * Many characters in The Father Luke Wolfe Trilogy who Father Wolfe encounters are either his own former students, or the parents of former or present students.
 * The many different plot threads in Peter F. Hamilton's Pandora's Star and Judas Unchained all follow different characters who, through one way or another, end up working against the Big Bad.
 * Many of the characters in A Confederacy of Dunces are completely unrelated until a comical convergence of events at the end.

Live Action TV

 * Lost. One of the DVDs even has a chart keeping score of the character interactions pre-island.
 * The first season of Heroes had this as a major theme, with all the divergent characters slowly coming together over the course of the story, culminating with all the characters' paths lead them to converge at Kirby Plaza for the final showdown to save the world from Sylar. Unfortunately, the later seasons seem to be trying way too hard to resist this trope, with increasingly illogical results. After coming together through S1, by S2 they're all scattered and many of them seem to have forgotten they know each other (literally in Peter's case) and from there on in they're always encountering problems they could solve if they just called in someone they know, and nine times out of ten they don't.
 * In Season 1, Mohinder (and Future!Hiro) both hypothesized that this is an implied side effect of having a superpower.
 * This doesn't even mention that virtually the entire cast is either a Petrelli or otherwise a relative of a Company member.
 * Love Soup's premise is based on the exact opposite. We have Alice and Gil, two Londoners who would be perfect for each other - if they knew they other existed. In the final episode you can see them sitting in the same theater without noticing each other - even though they are the only ones not laughing.
 * Doctor Who: Lampshaded by the Doctor in "The End Of Time Part 1"; he has just realised that  and is amazed that Wilf has been able to find him in the space of a day, where some people can spend years searching for him. Also happens with Donna in "Partners in Crime", so that the Doctor suspects that the Noble family have a very important role to play in events to come.
 * Pretty common in all Soap Operas.

Theatre

 * Twilight: Los Angeles.
 * This is the central premise of An Inspector Calls

Video Games

 * Final Fantasy VIII, where it's revealed that  Well, except Irvine—that's how they figured it out in the first place.
 * IIRC,
 * And in Final Fantasy XIII, as everyone is drawn to the same place through half a dozen different motivations.
 * The five playable characters of Odin Sphere (plus one very important NPC) run into each other all the time, and all wind up fighting to prevent Armageddon by the end of the game, . Also, they all end up being related in some way or other (Gwendolyn and Velvet are sisters, Cornelius and Oswald are cousins, etc.)
 * During the first part of The Legend of Zelda Ocarina of Time, Link helps a number of characters of various races in their homelands. Seven years later, the majority of them discover that they are actually the sages of various elements. While exceptions exist, the pattern is sufficiently established that, when Link goes back to his youth and meets Nabooru, the player can easily guess that the same thing will happen to her.
 * Hotel Dusk: Room 215: Every single person checked into the hotel has SOME connection to Kyle's search for Bradley. Every. Last. One. Well, Room 215 is called the wish room...
 * This is the defining motif of the visual novel ef (and its anime adaptations), in which the stories of five separate couples are ridiculously closely intertwined.
 * This is one of the defining motifs of Heavy Rain.
 * A trait of the story mode in Super Smash Bros. Brawl.
 * Live-A-Live. Without spoiling anything, just look at the names of each Chapter's Big Bad.
 * The majority of the Sonic the Hedgehog franchise, particularly Sonic Adventures 1 and 2, had Sonic and the other playable characters take separate routes, each relating to their respective arcs, only for all of them to intersect in an unlockable final-storyline.
 * Kingdom Hearts: Birth By Sleep had the three friends, including Terra, Ventus, and Aqua all take seperate routes that intersect with each other.
 * While Mass Effect 2 only takes place through Shepard's perspective, much like the original, that doesn't excuse the fact that the sequel was actually an anthology of ten-to-twelve character-stories, with each story relating to one of Shepard's teammates and their respective backstories. These stories are told through recruitment-missions, conversations with them on the Normandy SR-2, and most of all, the loyalty-missions, which increases Shepard's team's odds of surviving the final suicide-mission.
 * The first two Golden Sun games for the Game Boy Advance told the same story through two characters' perspectives, one per game. The first Golden Sun was about Isaac, as he quested to stop Felix from restoring alchemy to the land of Weyard. Meanwhile, the second game, Golden Sun: The Lost Age, was about Felix, as he quested to restore alchemy to Weyard before Isaac could stop him.
 * Deliberately invoked by Dr. Edward Roivas in the opening narration to Eternal Darkness.
 * This is the culmination of four games worth of metaplot in Assassin's Creed Revelations. The ending reveals for the first time precisely how Altaïr ibn La-Ahad, Ezio Auditore da Firenze, and Desmond Miles are related: a single shared moment when the three Assassins bridge the gap between the 13th, 16th, and 21st centuries and thereby allow Those Who Came Before to communicate across time to share their secret message.
 * In Ghost Trick, every single character is somehow connected to the backstory. The two strange inmates? The lady detective's young roommate?  In some cases it's justified, as

Miscellaneous

 * The cast of Dept Heaven Apocrypha has developed a tendency to become either distantly or directly involved in each others problems. Characters whose plots haven't fully begun yet like Monica and Meria are especially prone to this.
 * A standard in Live Action Roleplaying Games, as otherwise the characters would have little reason to interact with each other.

Western Animation

 * Guru Pathik of Avatar: The Last Airbender says that "Separation is an illusion." and that everything/everyone is connected.
 * Done in the My Little Pony Friendship Is Magic episode "The Cutie Mark Chronicles", where Rainbow Dash's first successful Sonic Rainboom is revealed to be indirectly responsible for all of her future friends (and herself) getting their cutie marks. They wouldn't realize this until they all met years later.
 * Phineas and Ferb basically runs on this. The lives of titular step-brothers, Perry the Platypus, and Dr. Doofenshmirtz, are constantly interwoven, often affecting each other without fail. The only character out of the four mentioned that is involved with all of the other three is Perry, Pet to Phineas and Ferb, Nemesis to Dr. D, and is basically in the middle of all the mayhem. Phineas and Ferb don't even meet Doofenshmirtz until The Movie, and even then