Save This Person, Save the World
The existence of the town, the human race, the universe, etc. comes down to the continued survival of one individual. For most of their lives, this person may not have been all that important in the grander scheme of things, but in this case at least, they are ultimately tied into the fate and destiny of their world. (Or at least enough people believe so to make a plot out of it, even if it later turns out that the character didn't really need to be protected.)
The goal, therefore, is to protect this person no matter what the cost. If they die, are gotten hold of by the wrong person, or are even just in the wrong place at the right time, then bad stuff will result.
Basically, this is what happens when the MacGuffin Girl meets the Butterfly of Doom, without necessarily having the fantastic, world-shaping elements that those plots usually require. The reason the character is important may be relatively mundane, emotional, and/or circumstantial in nature. They need not be a self-contained weapon, a Cosmic Keystone, an artefact disguised as a living being, The Chosen One, The Messiah, or a Barrier Maiden; they may not even have any special abilities to speak of (though that depends on the genre of the story). In some cases, they may have a strong emotional connection and relevance to the cast, so their death or even injury would result in the cast going off the rails somehow.
The other characters may not even know exactly why they're protecting this person. They may just have to be in a certain place in a certain time, or they may just have enough influence on others or on their surroundings that eliminating them would cause the situation to get a bit screwed up at best, and result in an apocalypse at worst.
Anime and Manga
- In Dragonball Z During the Android Saga, Trunks goes back in time to give Goku the antidote to a heart virus he had originally died from to hopefully save the world from the androids. Goku still ends up dying, but the world is saved this time.
- The current (and likely final) arc in Naruto is being fought to protect both Naruto and Killer Bee from from having their tail-beast extracted by the Big Bad Tobi/Madara.
- King of Thorn: Done subversively and surreptitiously in the manga—where everyone rallies to protect Kasumi, (who is in fact, Medusa) throughout the entire manga series. Their actions are mainly due to a directive imprinted in their minds by the Big Bad: "protect the small Japanese girl with your life". Most of them weren't even aware they were doing it. Of course, the bad guy wanted to reshape the entire world, not save it, so...
- Nodwick: Nodwick learns, in a variety of ways that he simply must exist for the world to continue relatively peacefully. In the Baphuma'al series, his companions would have succumbed to various artifacts or neuroses had he permanently died at some point.
- Not to mention if Piffany didn't exist, Nodwick would be dead (since nobody was there to revive him each time he was killed) and Yaeger and Artax were corrupted and ended up as Baphuma'al's Co-Dragons.
- The Terminator: kill Sarah Connor, and her son will never grow up to threaten the Big Bad.
- Terminator 2: Kill John himself, and he can't lead the Resistance.
- Again in Terminator Salvation: the machines try to kill Kyle Reese so that he will not go back in time and become John Connor's father, and the plot revolves around saving him.
- In Bill and Teds Excellent Adventure, apparently the reason Bill and Ted are given the time machine.
- Willow: Elora Danaan is destined to overthrow evil queen Bavmorda, the irony being it's her protectors who defeat Bavmorda because she was trying to kill the baby in the first place.
- Lampshaded in The Pacifier, where the lead character is incredulous to learn that "protecting these kids is a matter of national security". Vin Diesel's vacant "WTF" stare at the news is priceless.
- In the Star Trek: The Next Generation Novel Metamorphosis, after Data is granted his wish to become human, he is shown that his unique android abilities were the one thing which could prevent an all out war. Should he choose to stay human millions of people will die simply from his lack of ability to help them.
- An Isaac Asimov short story had this as a plot element. A man is pampered and kept away from all harm. The reason? It has been predicted by the Multivac computer that when he dies, the world ends.
- The four children in The Lion, The Witch, and the Wardrobe.
- The apocalyptic tone of The Wheel of Time has made it clear that if The Chosen One, Rand al'Thor, does not fight at the Final Battle, Rocks Fall Everybody Dies. (Of course, that may still happen even if he wins, so there are no shortage of people who think it's "Kill This Person, Save The World" instead.)
- Messily subverted in Stationery Voyagers. The Voyagers are never even told that Neone or Liquidon joining their crew is important. It just happens. Only Consto seems to find any relevance in Neone's fate at first for the greater picture of the universe, and even then, only so far as it fulfills an ambition that is merely a delusion of his own twisted mind. Neone and Liquidon do prove useful additions to the team, if only revealing their relevance much later on.
- Insomnia by Stephen King culminates in the main characters racing against time to save the life of a young boy named Patrick...whom they've never met, never actually meet during the course of the novel, and who's importance is never quite fully explained either. All they know is that the fate of the universe depends on them saving this one boy.
- To explain: The boy later grows up and becomes a pivotal character in The Dark Tower.
- In A Wind in the Door, Charles Wallace is the only person in any significant, physical danger. But his survival at this point in time is key to the continued existence of the universe as a whole. It's explained that this is the case because he has an important role to play in the future, and if he dies now the bad guys (who want to unmake EVERYTHING) will have a guaranteed win shortly down the line.
- Katniss Everdeen as the Mockingjay of the rebellion, starting at the end of Catching Fire. "While you live, the revolution lives."
Live Action Television
- Heroes. A whole season's Arc Words are "Save the cheerleader, save the world.", referring to Claire as being fundamentally important to the bad guy's plan for the reason that her particular powers (Wolverine-like healing) are the one thing he needs to fulfill his plot. The trope is Subverted after all this build-up: they don't save her, but manage to save the world anyway.
- As mentioned above, John Connor in The Sarah Connor Chronicles.
- Inverted in the Star Trek classic, City on the Edge of Forever: Save the person, doom the world.
- Doctor Who has an entire episode revolve around this. In "Turn Left", it is revealed that Donna meeting the Doctor saved the multiverse, as without her he would have died (along with several other companions who filled his role in various episodes) and nobody would have been left to stop the Dalek's Reality Bomb.
- Baby Eve from Being Human (UK) is an inversion of this. All of the good guys protect her, because she's the War Child, who prophecy says will kill all of the vampires, which means all of the vampires are trying to kill her. Then, it turns out that she has to die to bring about the death of all vampires, meaning that the protagonists who want to keep her alive are inadvertently screwing the world over. It's never really explained how Eve living would cause the vampires to win, but it's theorized that as long as she was alive, humans would stay lazy and expect her to be the one to save them.
Myth And Legend
- This is the premise of the first-person shooter Darkest of Days. The player is kidnapped by a mysterious organization and must travel through time to various historical battles and ensure that key individuals survive as part of an unclear and ongoing conflict between said organization and another group.
- This is subverted in the end of the game: it is revealed that said individuals' descendants were responsible for developing technology that fell in the wrong hands and was used to create a bio-weapon that devastated the world's population. The group opposing you is actually a future incarnation of your organization that decided to forgo their "Don't change history rule" to prevent the disaster.
- Subverted in Final Fantasy Dissidia: After Cosmos, guide to the protagonists, dies, the heroes still manage to gather up some Heroic Resolve and continue on with their mission.
- Done in StarCraft II, where it's Kerrigan. From Zeratul's and the Overmind's visions of the future, the Dark Voice will take control of the Zerg Swarm, and unlike Kerrigan has no problem using it to destroy everything, resulting in the extinction of the Terrans and Protoss, then killing the Zerg off once they're no longer necessary. If Kerrigan were to survive to that point, the swarm would still have a leader, thus preventing the Dark Voice from getting his army.
- You, in Baldur's Gate and its sequel in what is probably the most extreme that We Cannot Go on Without You has ever been taken to.
- Not all that overt, but in Devil Survivor, the entire possibility of saving humanity hinges on the suicidally-depressed singer Haru. Fail to save them, and you're locked out of the vast majority of the Multiple Endings, and in all likelihood stuck on the worst path of the lot.
- Ciem Webcomic Series: Who would've guessed that the epic chain of events leading to the downfall of Arfaas' control of Dirbine could be instigated by one distraught widow rescuing a Spanish-speaking six-year-old girl from a lowly pedophile?
- Dubious Company's pirates saving High Priestess Sal seems like this at first, until she reveals that she is not what Kreedor thinks she is and Kreedor's Elites know this. However, by that point it had become more personal.
- Justice League Unlimited: It's predicted that the death of the Flash will be a trigger for Armageddon since he's the Plucky Comic Relief keeping them on the rails. (In a Mirror Universe, his death instigated the rise of the Justice Lords). Flash lampshades this in "The Doomsday Sanction", to his own smugness and everyone else's annoyance. Only the Question is convinced it'll happen and attempts to kill Luthor himself to save Superman from it. This ends up making everything worse when Luthor reveals his Evil Plan. Flash does end up defeating Brainthor, so who knows...
- Fry, from Futurama has saved the world and universe twice due to being the only one without a Delta brainwave (due to past-nastifacation with his grandmother so Nibbler makes sure he gets frozen.