As with most Japanese (or rather, oriental culture) works, most of the lore and plot in Final Fantasy is very subtle, and sometimes never outright explained.
One of the aims of most of it is to allow you to contemplate the lore/plot as you will, but there is usually enough information to guide you on the important parts. With Final Fantasy XIII things are a little extra complicated because you are thrust into the universe in the middle of a chaos and never really given a preamble on what the lore is, and what is going on. If you either did not start the game, or you did (or even finished) but needs some light on the basic lore, you came to the right place. At the end, you will also find some information on Final Fantasy XIII-2 and Lightning Returns, also separated by non-spoiler and spoiler.
The fact that the english dub/sub is just TERRIBLE (due to localization, alas, "Westernization") also doesn't help people understand what is going on. Stuff like Snow telling Serah "We must come again next year" being translated to "This is all we need - you and me" totally changes what he meant, the emotional value of the statement and even the plot - and this is a minor instance.
For each game on the trilogy, the article is divided in two parts. First, the lore as it is when you start the game. No spoilers. Then, the lore as it is revealed by the end of the game. Like most religion, there are some half-truths (and some outright lies) in what people believe in FF-XIII universe that you uncover as you play.
A little table of contents
As it is at the start of the game (spoiler free)
The world was created by a great God, and God eventually created two races: The powerful fal'Cie, with some of his own extraordinary powers, and the humans, with no power at all. And then God left the world to it's own devices and went on for his/her own business.
The fal'Cie eventually disagreed among themselves on how to handle humans: some wanted to let them wild and free (and not care), while others wanted to help and foster them into an advanced civilization. Since fal'Cie cannot fight among each other, they decided to segregate: The ones who wanted to help humans, called the Sanctum fal'Cie, created the floating world of Cocoon above the planet. The ones who stayed on the planet – called Pulse (or Gran Pulse), were obviously called Pulse fal'Cie.
But they didn't rather like each other even though segregated as Sanctum fal'Cie was always aware of the hellish wild beneath them on the surface, and the Pulse fal'Cie always looking for that Cocoon of arrogant fal'Cie and their human followers.
The fal'Cie don't usually communicate with humans, but in Cocoon, the great leader of the fal'Cie, the Eden fal'Cie, sometimes will relay his ideas or orders to the human Primarch, who is currently Disley. The rest of the fal'Cie just keep Cocoon working: some provide light, other food, or energy and so on. The Pulse fal'Cie don't mind the humans on the planet, neither helping or harming them, been seen mostly as just a force of "nature"
But both sides wanted the other eradicated, and without being able to fight directly, the fal'Cie found out they could actually use humans. Once a fal'Cie wanted something done, it would choose a human (the closest one, it really doesn't matter) and brand him, giving him two things: Part of it's powers, thus making the chosen human powerful, and a goal (translated to Focus on the international version, but it's more like goal). These chosen/branded humans were called l'Cie.
Obviously after being granted super-powers, most l'Cie would just never mind his/her goal and wonder showing of the superpowers, so the fal'Cie had to do a little “incentive” play: If a l'Cie failed on completing his/her Focus, he/she would become a Cie'th. A mindless abomination full of hatred and violence (in fact, the original Japanese name is "chigau",which means "different" or, in this context, "abomination"). The time before a l'Cie have before turning into a Cie'th varies greatly according to that person's willpower, and the complexity of the Focus (the more complex, the more time the l'Cie is granted). However, since some humans would despair about being turned into a l'Cie, that basically meant he/she would never be able to complete the Focus, and so some humans become Cie'th almost instantly upon being branded a l'Cie.
As a reward for completing your Focus, the l'Cie is granted eternal life and a crystal form. While most people think about the “eternal life” part, they seem not to realize that they would expend it as a crystal statue … details.
And then the fal'Cie start branding humans into l'Cie to do their bidding. While the Sanctum fal'Cie don't really have much of a need for l'Cie, the Pulse fal'Cie want that Cocoon torn asunder out of the sky, and start creating l'Cie with the goal of destroying it however possible. Centuries before the start of the main plot, the Pulsian l'Cie were able to amass a human army strong enough to break the Cocoon defenses in what was known as the Transgresion War. While they did considerate damage, including blowing off part of the Cocoon shell (that's why it has a hole), they ultimately failed.
Ever since, the population of Sanctum is afraid of when the evil Pulse l'Cie might be back again, and a special branch of Cocoon army is specially tasked with locating and ridding of Pulse l'Cie as soon as possible before they grow in numbers or do any damage – the PSICORPS. However, it has been ages since the last Pulse l'Cie was seen.
This is where the game starts.
Nothing short of a Pulse fal'Cie was found in old remains of the Transgression war, and to make things worse, it started making l'Cie. Without any way to know who have already been turned into l'Cie or not, the Sanctum government decide to completely purge the neighborhood of Bohdum, sending them to the hellish wild that is the surface world of Pulse.
As the game starts, Lightning – a former Sanctum soldier, fights her way in a Purge train with some special objective, while Snow, leader of a movement that usually fights against wild-life that still lives on the outer shell of Coccon, have to take arms against the PSICORPS who, realizing it's easier to just terminate the population than to try a calm purge, starts killing everyone. The characters eventually will get together and have problems and goals of their own, all connected to the recently discovered Pulse fal'Cie in Bohdum.
- fal'Cie: Created by God, have super powers, but cannot fight other fal'Cie directly;
- humans: Also created by God, no (apparent) super powers;
- l'Cie: humans who have been given super powers by a fal'Cie in order to complete a specific Focus (goal);
- Cie'th: l'Cie who fail their Focus (run out of time, get into despair, etc) and become wild abominations;
- Crystal form: l'Cie who complete their Focus are granted eternal life … as a Crystal;
- Pulse: The planet where all takes place, the “surface” world;
- Pulse/Pulsian fal'Cie: fal'Cie that reside in the surface world, and chose not to care much about humans, but still hate the Sanctum fal'Cie;
- Sanctum fal'Cie: the name given to the fal'Cie who decided to help humans reach a highly evolved society, protected by the wild beasts of Pulse inside Cocoon, they don't care much about the Pulsian fal'Cie, but have to defend themselves;
- Cocoon: The huge floating “island”, created by the Sanctum fal'Cie to work together with humans as a safe haven away from the wild surface;
- Transgression War: A war, centuries ago, where several Pulse l'Cie and their Pulsian human followers attacked Cocoon trying to destroy it. Although they did some extensive damage, they failed;
As it really is (lots of spoilers)
Most of the original lore is right, with some minor (extremely important) details. First, the basics, from FX
Almighty Bhunivelze created three gods for his world: Etro, Pulse, and Lindzei,
Etro was a goddess without any power of her own. In contrast, both Pulse and Lindzei were granted near limitless power, and they build the fal'Cie, servants that possess supernatural powers.
The fal'Cie that served the god Pulse worked to terraform the expansive lands of the planet, and the world came to be known as Gran Pulse. The fal'Cie which served Lindzei built a world in the sky, and kept humans blissfully unaware withing a cage they called Cocoon.
The gods did not reveal themselves, but the fal'Cie were present in every part of humanity's lives. The people depended on them for survival and worshiped them as gods.
- excerpt from FXIII-3 Lightning returns, which is the most complete lore on the FXIII universe
As of the first game (which is all we cover in this article), we are only aware of the fal'Cie. When fal'Cie mention God, they are talking about Bhunivelze, the great creator. Pulse, Lindzei and Etro (which just so you know is the goddess of death and chaos, presiding over the souls and ensuring they are reborn) are only important on the second game, and Bhunivelze on the last.
The fal'Cie never disagreed as we are led to believe initially. They want to bring back the God who created them, and they figured that if enough people die at the same time, it would attract God's attention. So they create Cocoon to nurture a big civilization – only to eventually kill them all and get God's (Bhunivelze) attention. To create fear (which could be one of the triggers to such destruction), some fal'Cie remain on the surface and nurture it's population against Cocoon, doing a guerrilla style war just to keep Cocoon always afraid (the Purge, all a ruse to amp the fear), while also trying other schemes like outright war, a super l'Cie (Ragnarok) or conspiracy inside Sanctum. It is unclear if the Pulse fal'Cie and Cocoon (Lindzei's) fal'Cie always believed that or if the plan for human destruction came later ... probably so, it doesn't matter.
Mind you, Eden fal'Cie was never in charge, he was just a facade. The one really in power was Disley, pretending to be a human. Disley is Bartolomeus fal'Cie, the mastermind of all this ruse, and believes that with his and Orphan fal'Cie death, Cocoon would be doomed and the slaughterer would bring back God and "return them to their glory".
A normal l'Cie don't have enough power to kill a fal'Cie (as we can see, a party can), but one with enough hatred and power can become a creature known as “Ragnarok”, and fight in pair with a fal'Cie. During the Transgression war, one Pulse l'Cie became Ragnarok and almost managed to destroy the core of Cocoon and – thus – make it fall and shatter on the surface, instantly killing all. That l'Cie was Fang, but at the last minute she failed to kill Orphan (the core of all Cocoon floating power). Some believe God (Lindzei) had a hand in preventing her fulfilling her Focus, but in fact, it was just that she didn't really want to do it - the real human power is free will (it is eventually revealed that even the gods can't see the human "heart" - alas, their emotions). Partially completing her Focus, she and Vanille were turned into Crystal and hidden with the Anima fal'Cie in the Vestige – an old relic – until they were awaken again when human population in Cocoon were large enough for another try.
An important bit of false information is about l'Cie and their Focus: The fal'Cie can give powers to humans, but can't really turn them into abominations, crystal or define their fate. It is actually a normal consequence of despair and lack of hope which turn a l'Cie into a Cie'th, while it is also the sense of completing one's goal that give them the crystal form. In both cases, they have eternal life, except one an abomination (that might eventually loose all will and become stone), or a crystal. Since they are still alive in any of those forms (or rather, their soul is), they can actually be awoken. Usually fal'Cie wakes up a crystal when they want said l'Cie to perform the same Focus, but any other l'Cie can communicate and awake a crystal form. Also, if a Cie'th were to get hope back and snap out of despair, he/she would also be able to go back to being a l'Cie. And if you are strong enough to snap out of the control of the fal'Cie, you can even be back to human.
In the final sequence, everyone turns into Cie'th when Fang decides to become Ragnarok, because basically they loose all their hope of not having to destroy Orphan. However, upon Fang failing again (because deep down she doesn't want to), they realize that the human spirit has far more power than that of fal'Cie – that is the “power” humans have that fal'Cie don't: free will, a free spirit (fal'Cie can't even fight among each other!). The fal'Cie never really had any power on their fate, it was only “smoke and mirrors”, manipulation, making people despair. With that, the recently-turned-Cie'th are given back their hope – multiplied – and are able to become l'Cie again. They don't know if it were all a trick to get Fang into Ragnarok or they really became Cie'th, but they remember being “trapped” in despair until they saw hope and a future – so, yes, they became Cie'th.
And in the end, even the branding were not fully controlled by fal'Cie. Once given powers, a human could use it to snap out of being a l'Cie from their own willpower – and that is why in the end, all the l'Cie loose their brands (some eventually actually turn back to l'Cie in the following games). They have no more need for it. Unfortunately, Fang and Vanille used their power to crystallize the lava of the Pulse core to hold Cocoon in the air, and therefore are trapped in Crystal form – but they are happy, they did what they really wanted: save the world.
The real mind wrapper is this: the Focus image that everyone saw when turned into l'Cie was actually Ragnarok plunging into the lava (which doesn't really match an image where Ragnarok just destroys Cocoon) .... so, was indeed their Focus to save Cocoon? Was Anima fal'Cie against mankind slaughter?
Real world Analogy
If you fully understand the nature of the fal'Cie, you will realize that it is based on real world religion. Fal'Cie can easily be understood as “false Gods”. L'Cie are the most devout humans who will do whatever these “false Gods” want, even though they don't even have much of a clue what is it they want – and if they think they failed (keyword: their feelings, not something the fal'Cie do), they spiral into despair and go wild and violent – a Cie'th – or are granted eternal respite – which doesn't exist, so they turn into crystal. But they all hold their free will, and can snap out of Cie'th, Crystal and even being a l'Cie if with enough will-power.
Spoiler free if you played the first game, otherwise spoilers on the first game
Understanding this lore makes the follow ups a lot easier to understand.
As they arrive at the surface at the end of the first game, Lightning vanished and only Serah remembers her existence. Also, a new character from a new "dimension", Noel, meets Lightning in a world called Valhalla, and gets from her the mission to help Serah "save the world".
When the fal'Cie fell (actually, one is still alive and works as the food source all the way to the end of the last game), all the humans that "worked" for the fal'Cie lost their bindings.
Back on the surface world, there is a seeress that can see the future, she is called Yeul and dates back since the dawn of time. As the fal'Cie loose their grip on her, her predictions become erratic and create paradoxes in the timeline. One of such paradoxes "swallow" Lightning: the paradox is, indeed, that nobody remembers her, but she is the reason everyone is alive.
Lightning is rescued by Etro (remember her, from the three beings created by the great Bhunivelze God?), the goddess of death and Chaos, and becomes the knight of Etro, her protector - it doesn't matter what happened to the fal'Cie and their creators, the gods Pulse and Lindzei, life still requires Etro to manage the chaos and souls back into rebirth, and with the loss of the fal'Cie control, Etro turns Lightning into her protector. Etro's domain? Valhalla.
But as Yeul's predictions create more and more paradoxes, Lightning realizes something most be done. She contacts one of Yeul's protectors, Noel, and gives him the mission to contact Serah, the only person who still remembers Lightning, and travel through time fixing the paradoxes and, if possible, preventing the new doom that is predicted: the fall of Cocoon as the Crystal pillar collapses.
The price for the seeress power is that she dies before maturing, with a last big vision. To keep her soul safe and the visions contained, protectors are assigned for each of her reincarnation ... that is, until Caius arrives. Caius falls in love with Yeul, and eventually Yeul loves him back, and that is the source of the paradoxes, because her feelings start creating changes in the future and, therefore, her visions. Furthermore, Caius is immortal (eventually revealed to be from Yeul's multiple souls power), which doesn't really help, because he sees multiple Yeuls be born and die. Eventually, he decides it has to stop, he must prevent her reincarnation, and there is only one way to do it: Slay the one God responsible for the dead ... Etro. So Caius goes after Etro in Valhalla some 400 years after the events of FFXXIII, backed by his immortality and amazing powers from Yeul. Yeul can see this end, but it only creates more and more paradoxes: she wants to be saved, but she doesn't want it to mean the end of the world. Between Caius and Etro is Lighting.
So, in the end, despite Noel and Serah managing to mend most of the paradoxes created (unwillingly) by Yeul and even help Hope with preparing the new Arcadia (Ark) to save everyone when Coccon inevitably crashes, they too have to face of Caius. What is worse: it is revealed that the reason Serah remembers Lighting is that she have seeress powers like Yeul, and start having visions through the game, which means that eventually she will perish like all seeress do.
To try and avoid that, Lightning tries to stop Caius and his plan. While Lightning stop Caius, Serah has a last vision nonetheless and perishes. The shock of having Yeul, Caius and Serah lost creates a surge in chaos and thus costs Etro her life, and the Chaos starts flooding the world - the only way to stop it is for someone to take on Etro's place, and so Lightning sits at her throne and crystallize, containing the flow of chaos and stopping the end of the world ... or so she thought.
Spoiler free if you played the earlier games, otherwise spoilers on those first game
As the name implies, Lightning awakes from her slumber 500 years after crystallizing (900 years after the first game). What she did not know is that her effort was only a stop gap: she hugely reduced the speed at which chaos flooded the world, but it still does, and what is worse, Etro was also responsible for managing the souls and sending them back to be reborn, which is a power Lightning does not possess.
At the time that Lightning took Etro's place, people could no longer be born, and so those alive also stopped aging. But one could still die from accidents or murder/monster attacks, so the number of people kept reducing, while chaos also kept flooding and destroying the world (more dead with nowhere to go).
The great Bhunivelze, realizing the world is lost, decides to start a new world. For that, he needs to fetch the remaining souls to populate such new world. He awakens Lightning and gives her 13 days to save as many souls as she can (not killing them, but rather making them fulfilled in this life), offering to bring back Serah if she succeeds. That is the whole point of why you have a ticking clock in the game: save as many souls as you can.
But what makes people special is that not even Bhunivelze can see into their soul, their hearts - that is why he had to ask Lightning to do so in the first place. Eventually, Lightning realize (helped by hints from multiple people) that if that is so, Bhunivelze can't actually even know where Serah's soul is, let alone bring her back!
The Serah Lightning sees, believing to be a "preview" from Bhunivelze to do her work, is a fake.
To make things worse, Bhunivelze doesn't want all the "bad baggage" from the dead to come into the new world: he plans on having them purged, only those who are fulfilled and alive at the last day would be saved, and when the souls are destroyed, all the memories about them would also vanish, giving the new world a clean slate to start, with no sorrow - and no Serah.
Lightning also learns from Yeul and Vanille that the chaos is nothing short of a manifestation of the departed souls. Since Etro is no longer managing the souls back into life, every dead just adds more chaos to the world. And Bhunivelze plans to have Vanille destroy all the souls.
Lightning realizes that in order to have Serah back (into the new world), she must stop Bhunivelze plans, change Vanille's mind into sending the souls to the Ark instead of "cleansing" them as the Order preaches, and obviously, she will have to face Bhunivelze wrath once she betrays him. The plot twist here is this: Bhunivelze can't see what humans fell or think, so he doesn't know what Lightning is planing.
The mysterious girl Lumina knows that, and also give hints about Bhunivelze plan to Lightning when Lightning is traveling between worlds - away from Bhunivelze eyes. We also eventually learn that the reason why Hope can't see what is going on inside Chaos is that he too is a fake, Hope is long dead, the Hope in the Ark is a Bhunivelze puppet to spy on Lightning, and as mentioned, Bhunivelze can't see into people's hearts and souls (chaos).
Lightning convinces Vanille to save the souls, much to Bhunivelze dismay. With the power that Bhunivelze himself gave her, plus the "power of the human soul" that makes Lightining unpredictable, she "defeats" Bhunivelze long enough so all the souls combined destroy him (this happens at the ending cinematics), thus setting humans free of all the shackles of "gods and crystals" into a new world: our world (see post credit scene).
Minor plot twist: Lumina represents Lightning emotions, long locked away. She pretends to be Serah at times, or know Serah, because she knows Lightning true feelings (she IS Lightning emotions). In order for Lightning have the power to really face off Bhulniveze in the last cinematic, she have to accept her and open her feelings (merge with Lumina, which is revealed to have the appearance of a young Lightning), and thus receive all her "powers" (humanity) back.
Serah? Serah never knew a thing, she was long dead and away from anyone's reach (as she died on when she had her view), even God! It was all either a fake from Bhunivelze, or from Lumina (Lightning emotions). In the end, who really brings Serah back is Mog, who Lightning cleverly realized was the necessary beacon to bring her back.
Gods dead, all souls saved, new universe created, everyone can be born again in a world free of the shackles of Gods and semi-Gods whims. The end.
Post credits scene: And here we have Lightning reincarnated in present day Europe. Plot Twist: All trilogy is a prequel for our universe!