Final Fantasy XIII-2 story

The story of Final Fantasy XIII-2 spans various eras and locales, as Serah Farron and Noel Kreiss set out on a journey through time to find Serah's sister Lightning in a mysterious realm known as Valhalla. During their travels the pair seeks to solve the mystery behind the paradoxes that threaten the timeline, and to prevent a bleak future.

Prologue
At the end of Final Fantasy XIII -Episode i-, Lightning, who felt there was still something threatening the newly acquired peace, found herself dragged into the Historia Crux by a mysterious substance known as chaos due to the effects of the goddess Etro releasing her, Snow, Sazh, Hope, Serah, and Dajh from crystal stasis.

As a result of Lightning being written out of history, many believe her to be either dead or crystallized with Vanille and Fang in the crystal pillar. Only her sister, Serah, remembers reuniting with her after Cocoon fell and knows she is still alive.

Lightning awakens in Valhalla, a dark and empty world that exists between the mortal realm of the physical universe, and the formless unseen realm of the chaos. She enters Etro's temple. Seeing all of time from Valhalla, she looks into the future and receives a suit of armor, becoming the protector of the dying goddess, who had expended all her strength to stop the escaping chaos from seeping into the mortal realm. From that point on, Lightning engages many battles against a man who seeks to destroy Etro, named Caius Ballad.

Within Etro's temple in Valhalla, Lightning looks out from the balcony and has a vision of a boy in the Historia Crux. Meanwhile, Caius lays the lifeless body of a girl named Yeul to rest in the ocean of chaos that surrounds Valhalla. He summons an army of Rift Beasts and challenges Lightning to battle, and she confronts Caius with her own army of summoned monsters and Eidolons. During her and Caius's battle spanning across Valhalla, Lightning notices Etro's gate—the portal to the mortal realm—open over the temple, and sees a familiar figure fall from the sky. She recognizes it as the young man she had previously seen in a vision, Noel Kreiss.

Summoning Bahamut, she saves him from his fall, but Caius returns as Chaos Bahamut to continue the fight. Lightning asks Noel to find her sister Serah and bring her to Valhalla. She summons a moogle named Mog for Noel to give to Serah, but Caius summons a meteor over Etro's temple. Summoning Odin, Lightning thrusts herself into the meteor's path as it crushes the temple. Noel leaps into a Time Gate to find Serah in the past.

A journey through time
By the year 2 AF, many former residents of Cocoon have created settlements on Gran Pulse, like the village of New Bodhum near Cocoon's crystallized structure, and some have gained the ability to wield magic. One day, Snow promised to look for Lightning and bring her home so he and Serah can finally get married, but a year goes by and he goes missing as well.

In New Bodhum at 3 AF, Serah dreams of Lightning's battle with Caius and Noel coming to New Bodhum to help her. After a crystalline meteorite falls from the sky, she awakens to find her clothes mysteriously changed. As she heads outside to the shouts of NORA, Serah sees the village transform into a wasteland. When the village reverts to normal, it seems time has stopped and New Bodhum has fallen under attack by monsters. Once time resumes Serah finds herself amid the battle and is saved by Noel. With little time to talk, Noel hands Serah a weapon enabling her to fight off the monsters with him. Serah's weapon transforms into her new moogle companion. Noel says Mog is a gift from Lightning, much to Serah's shock.

At the meteorite's crash site Noel reveals he is from 700 years in the future, and that Lightning is waiting in a place called Valhalla. He offers to take Serah to her, but the NORA members remain skeptical. Placing Serah's hand on the meteorite, Noel shows them it is really a Time Gate. The next day, Noel and Serah use Mog to search around the village for an artefact that will let them use the gate. After finding it, Noel reveals he is from a distant future where all of humanity was wiped out until he was the only one left. Joined by Noel and Mog, Serah leaves her home to find her sister, but unknown to both of them, they are being watched by Caius and his companion, Yeul.

Noel and Serah travel through the Historia Crux, the crossroads of the time continuum, to the Bresha Ruins in Cocoon two years in the future at 5 AF. They battle an invisible giant called Paradox Alpha, revealed to be Atlas, a war machine from the future that has appeared in the wrong time period due to a paradox. Serah and Noel are arrested for being in a restricted area, but they are freed by an Academy scientist named Alyssa Zaidelle. Alyssa asks them to help defeat Atlas before it shuts down the site, as she is in search of something in the ruins.

By destroying the crystal atop Atlas's head, Noel and Serah defeat him and solve the paradox, restoring the Bresha Ruins to their former glory. Serah and Noel find what Alyssa was looking for: a grave belonging to her friend who died in the Purge five years ago, and is glad to see her name is not on the grave. Alyssa reveals she often dreams of dying in the Purge and wonders if she really did and her current life is an illusion. Hearing Alyssa's story, Serah laments how the Purge happened because she was made a l'Cie.

Serah, Mog and Noel travel to the Yaschas Massif in the year 10 AF, which is darkened by an eclipse. Noel says that 500 years before his time the fal'Cie Fenrir appeared and blocked the sun. Serah figures Fenrir appearing in 10 AF is a paradox as it's only affecting a certain area. They find the Paddra ruins and meet the Academy leader, a 24-year-old Hope Estheim, with an older Alyssa who is now Hope's assistant.

They learn from Hope and Alyssa about the Farseers, a nation led by the seeress Yeul who had foretold the city's destruction, inciting conflict among its people and the prophecy to be fulfilled. With the ancient device called the Oracle Drive they witness images of the events on the Day of Ragnarok and Lightning in Valhalla. Using the new artefact they got from Hope, Serah, Mog and Noel enter a Time Gate to solve the paradox causing the eclipse that also is affecting the Oracle Drive.

They wind up in Oerba during the year 200 AF, only to find it being sucked into a void. After solving the multiple paradoxes, they find another Oracle Drive at the old schoolhouse that projects images of Serah's reunion with Lightning, but are apprehended by Caius and Yeul. Noel is shocked to see her and calls out her name, but Caius reveals there is more than one Yeul across different eras, and that she is not the Yeul Noel knows. Yeul has been watching them through her seeress's visions, and Caius seeks to punish Serah and Noel for tampering with the timeline. After a battle, Yeul and Caius leave Oerba, and Noel and Serah use the artefact they left behind to leave as well.

As they have solved the paradox in Oerba, they have also solved the paradox in the Yaschas Massif. Serah and Noel arrive in an alternate version of the Yaschas Massif in the year 10 AF, also known as 1X AF, where the eclipse never happened. They meet another Yeul, who says she and Serah are the same in how they can show others the way. Hope and Alyssa are still at the ruins and the four reunite, even though Hope and Alyssa don't remember meeting them before, causing Serah and Noel to repeat their meeting. Hope shows a recording from the Oracle Drive, which displays clear images of Lightning battling Caius in Valhalla and Cocoon's crystal pillar crumbling.

Hope will have the Academy prepare for the time Cocoon will fall to try minimize the damage while Serah and Noel continue to solve the paradoxes. After Serah and Noel leave, Yeul dies in Caius's arms and he takes her body away. Serah and Noel end up in the rift between gates known as the Void Beyond where they briefly explore before returning to the Historia Crux.

They go to the Sunleth Waterscape in 300 AF where Serah has a vision of Snow in danger. They find Snow battling a giant flan called Royal Ripeness, but upon defeating it together, it regenerates. After Noel demands Snow to explain why he left Serah and is now fighting in the future, Snow reveals the reason Serah never heard back from him is that he has also become a time traveler. He explains Lightning had appeared to him in a dream, asking him to protect Cocoon's pillar, and in turn, Fang and Vanille resting inside it. Following a trail of Miniflan, they find two artefacts to use in solving the paradox causing Royal Ripeness to grow. As Snow stays behind and promises to wait for them, Noel, Mog, and Serah first visit the Coliseum, and obtain the White Hole fragment, the source of the local paradox, from the Arbiter of Time.

Next they venture to the Archylte Steppe at an unknown time period where they learn from a group of hunters that a faeryl is sucking flan into its mouth, summoning them in the Sunleth Waterscape. Defeating the faeryl, the trio receives the Black Hole fragment and returns to Sunleth Waterscape, only to find Snow not waiting for them like he had promised. They find him fighting the Mutantomato, the flan's true form without being affected by a paradox, and they defeat it together. Noel reprimands Snow for his recklessness. Snow apologizes and asks Noel to look after Serah for him. When Snow begins glowing, Noel says it is because the paradox has been resolved and things that shouldn't exist in this time are disappearing. Serah notices a l'Cie brand on Snow's arm before he fades away. Noel says Snow may have asked to become a l'Cie to get the power to protect his friends and carry out his task.

Noel, Serah and Mog enter a Time Gate and emerge in the Void Beyond deciding to take a break. Noel tells Serah the Farseer tribe from which he hails from always had a girl with the same appearance, voice, and power who was always called Yeul. They end up in the city of Academia in 400 AF, a highly advanced Pulsian city under the control of a Proto fal'Cie. The fal'Cie spots Serah and Noel and transforms citizens into Cie'th.

Serah, Noel and Mog run into Caius who tells them they are contradictions in the timeline and that he has every reason to eliminate them. He tells them they met in a tower 200 years earlier and that they died there after learning the forbidden history sealed inside. Now that they are here, alive and well, they have caused a paradox. Caius leaves them with a band of Cie'th and after defeating them, Serah, Noel and Mog give chase to Caius, but he disappears every time they catch up to him. They run into Yeul being attacked by several Cie'th, including Zenobia. After Serah and Noel defeat Zenobia, Yeul tells Noel about her vision of death before Serah realizes Yeul is dying because they are causing a paradox. Yeul tells them Caius was never in the city and dies, leaving them an artefact. Serah, Noel and Mog use a nearby gate to travel to the Augusta Tower in 200 AF.

In the tower, they spot Caius ascending its levels. They discover the tower's staff are artificial duplicates, and meet a duplicate of Alyssa who reveals the forbidden history from the year 13 AF. During that time the Augusta Tower was built as part of the "Proto Fal'Cie Project," Hope's plan to re-levitate Cocoon without the crystal pillar. The tower's artificial intelligence rebelled against its creators and killed everyone, including Hope and Alyssa. Afterwards, the AI constructed the Proto fal'Cie and created duplicates to cover the massacre.

Serah, Noel and Mog make their way to the top floor where they meet the same Yeul they had met in Oerba, who gives them an artefact. Yeul reveals Caius is immortal and knows the entire timeline from remembering the seeress's visions. She explains Lightning's disappearance from Gran Pulse was caused by the future being changed and that if Serah and Noel continue to solve the paradoxes the past will return to the way Serah remembers it. She reveals the Caius they encountered in Academia was a fake created by the sentient AI, and that they saw the real Caius in the tower. Serah and Noel venture into the core to defeat the AI. Yeul sees the future where everyone is happy and dies smiling. Caius arrives and mourns for Yeul, vowing to remember her pain, and takes her away.

Serah and Noel arrive to the tower's core and encounter the Proto fal'Cie Adam, which is using the AI and a paradox to keep itself functional and it is reincarnated every time Serah and Noel defeat it. As a last resort Serah shouts at Hope for creating the Proto fal'Cie. Her yelling reaches out to Hope via the Oracle Drive and the Proto fal'Cie ceases to exist after Hope decides not to build it the first place. Having resolved the paradox, Serah has yet another vision.

Serah, Noel and Mog end up in Academia in a new timeline at 4XX AF where everything is well now that the Proto fal'Cie is gone. They are greeted by Hope and Alyssa, who used a time capsule Hope invented to get to Academia in this time period without aging. Back in 1X AF Hope had begun the "New Cocoon Project" to create a new Cocoon after the old one is destroyed when the crystal pillar collapses in the future. After seeing the Thirteenth Ark in the Oracle Drive in 13 AF, he and Alyssa entered the time capsule and awoke in Academia to learn how it can be made airborne. For his New Cocoon Project to succeed, Hope requires five Graviton Cores hidden throughout the timeline to make his new Cocoon float.

Serah and Noel retrieve the Graviton Cores and Alyssa gives them an artefact to use the new Time Gate back in town. Hope and Alyssa meet them at the gate to see them off, promising to meet again a century in the future. When Serah and Noel enter the gate Alyssa smirks but only Mog notices. When Mog follows after Serah and Noel, he and Serah get separated from Noel in the Historia Crux. Alyssa betrayed them and tricked them into Caius's trap because she is a living paradox and won't exist in the corrected timeline.

Revelations
Serah and Noel end up in the Void Beyond where Mog is phased out and becomes invisible to Serah, and Noel is impaled by Caius. Serah goes on alone and meets several Yeuls from different time periods. Each Yeul tells Serah certain truths about her, the l'Cie who saved Cocoon, and history's change, ending in revelation that like Yeul, Serah has the "Eyes of Etro," the ability to see the future, a skill granted by the goddess herself. The last Yeul tells Serah that whenever people die in the Void Beyond it takes the shape of their heart's desires, and warns her that as she changes the timeline she brings herself closer to death.

This Yeul transforms into Caius, and Serah is forced to fight him. He tells her about Noel's fate and that as the result of Etro freeing her and the other l'Cie on the Day of Ragnarok, the lives of the Yeuls throughout time were cut short. Caius plans to send everything back to Valhalla to save Yeul from her fate of constantly being reborn even if it means destroying time itself. Caius impales Serah from behind causing chaos to burst from her body.

Serah, in her old clothes, is awakened in New Bodhum by the NORA members. She is confused as they tell her she never left on a journey and have never heard of Noel. When she heads into the NORA House she finds Snow. It seems she is in a dream where everything is the way she wants it to be: she is married to Snow and Lightning never disappeared. When the fake Lightning attempts to convince Serah to remain in the dream world forever, Serah remembers the real Lightning is fighting in Valhalla waiting for her, and refuses, causing the fake Lightning to disperse into chaos.

Serah hears a familiar voice giving her words of encouragement and encounters Vanille and Fang. The pair reveals they reached Serah since she rejected the fake Lightning and came to help her escape the dream in the Void Beyond. They tell her Noel needs her help to escape from his own dream. Leaving a spacetime distortion to lead Serah to Noel, Vanille and Fang return to their dream inside Cocoon's pillar. Serah heads into the distortion to find Noel and save him.

Noel is caught within his own dream world based on his past memories from his home of the Dying World at 700 AF. Serah follows Noel and witnesses his conversations with Caius and Yeul. Caius tells Noel he must kill him to become Yeul's next Guardian and receive his Heart of Chaos, a manifestation of Etro given to him by the goddess centuries ago to make him immortal. Should it stop beating the goddess will die, the unrestrained chaos of Valhalla will be unleashed into the mortal world, and history will be destroyed.

Noel refuses and Caius forces him into a battle. Caius defeats him and realizes Noel is not strong enough to kill him. Caius uses the affinity he has with chaos to depart for Valhalla to slay the goddess Etro to free Yeul from her cycle of reincarnation, abandoning Yeul as her Guardian for the first time. Serah witnesses Noel talking to Yeul who has a vision of the future and dies in his embrace, promising him they will meet again. Noel pursues Caius and gets drawn into the sky by a light which would lead him to Valhalla, but Serah catches up to him and helps Noel awaken from his dream. Serah wants to continue their journey, but Noel is reluctant, because he now knows why Yeul died. Every time a seeress has a vision of the future a piece of her life will vanish, and if she has a vision strong enough she will die. Since Serah has the same ability, she, too, is in danger of dying the same way each time she and Noel change the timeline, but Serah is willing to take the risk to save the future.

Serah and Noel return to where Yeul died, and the Oracle Drive shows her dying vision of Noel fighting to save the future and the two of them reuniting. A distortion appears and Mog returns to normal. Mog reveals his soul was trapped in the Void Beyond until Lightning saved him. It is revealed that Caius was once a Pulse l'Cie with the Focus of Yeul's protection, until Etro saved him and made him immortal by giving him her Heart of Chaos. Noel and Serah realize Caius has been plotting for centuries, using his immense power and knowledge of Yeul's visions to create the paradoxes to reach his goal: the goddess's death and world destruction.

Serah, Noel and Mog go through the time distortion in the Dying World and end up in New Bodhum in 700 AF, finding the village a desolate wasteland. They meet Lightning who has come from Valhalla. She explains everything that happened to her and what Caius is plotting: Caius is trying to destroy Cocoon so the surge of departing souls would open Etro's gate and send waves of chaos to erupt from Valhalla. Chaos would engulf the world, turning it into a place where time, life, and death don't exist, essentially remaking the world in Valhalla's image.

Noel realizes Caius is doing this for Yeul's sake to stop her from suffering her cycle of death and rebirth. To prevent this, Caius must be stopped in both Valhalla and the mortal world. Since Lightning can't do this alone she needs help from Serah and Noel. She tells them that in the year 500 AF, Hope will launch the new Cocoon and Caius will attempt to bring it and the old Cocoon down in one fell swoop. Lightning tells them if they save the new Cocoon and stop Caius, the timeline will be restored.

Mog reveals a new gate to take Noel and Serah to 500 AF and Lightning prepares to return to Valhalla to face Caius. Serah asks her if they will be together again when everything is over, but Lightning only smiles and replies, "One thing at a time, Serah," and leaves.

Promised eternity
Serah, Noel and Mog arrive at Academia at 500 AF, the time of the prophecy, but the city is a labyrinth of chaos and the populace has been evacuated to Hope's new Cocoon. As they journey through the area they hear Yeul's voice warning them not to fight Caius and kill Etro. Reaching the Academy headquarters, Caius, who has arrived from Valhalla, attacks them as Chaos Bahamut and with summoned monsters, but they are saved by Hope. They give chase to Caius on an airship piloted by Sazh Katzroy, another of their time traveling friends, and Serah and Noel fight Caius as Chaos Bahamut and his human form. A portal in the sky leading to Valhalla opens and Caius flies into it as Chaos Bahamut. Hope is eager to go after him, but Serah insists he must stay behind and protect Vanille, Fang, and his new Cocoon.

Serah, Noel and Mog jump into the portal and encounter Caius in Valhalla. They defeat him but he still swears to stop Yeul's cycle of reincarnation by destroying Etro. Noel attempts to convince Caius Yeul wouldn't want the world destroyed, and that she kept returning out of her own will because she wanted to be with him. After Noel cuts him down, Caius transforms into his ultimate form, Jet Bahamut, and blasts at Serah and Noel. The pair falls into an abyss beneath the waves of chaos, but Lightning saves them, urging them to keep hope alive. Serah and Noel defeat Jet Bahamut, and his supporters—Garnet Bahamut and Amber Bahamut—and Caius reverts into a human.

Caius claims that if what Noel says about Yeul is true, then Noel must kill him. When he refuses, Caius tries to provoke Noel by saying he had killed Lightning, but Noel tells the shocked Serah that Caius is lying. Caius claims to already know how everything will end and provokes Noel by lunging at Serah. Noel intervenes, but Caius takes Noel's blade and tells him that those who change time must choose who lives and dies, and that Noel must bear the burden of the eternal paradox. Caius forces the blade through his heart and as he slowly disappears, Serah and Noel realize that Caius had been consumed by sorrow over the centuries for watching so many Yeuls die, and always wanted to die in Valhalla to end Yeul's suffering. With the final paradox resolved the timeline is fixed, and Serah, Noel, and Mog return to Gran Pulse in 500 AF before the Time Gates disappear.

Possible endings
There are nine possible endings in Final Fantasy XIII-2:

Canon ending
After Caius's defeat, Sazh, who has also become a time traveler, removes Fang and Vanille from the crystal pillar before the old Cocoon falls. The new one, named "Bhunivelze," rises into the sky. Serah, Noel, and Mog return from Valhalla, but everyone's victory is short-lived when Serah has another vision and dies in Noel's arms prior to Hope arriving from Academia to greet them. The sky darkens and Mog grows weak, saying the goddess is gone. Noel remembers Caius's warning about Etro and the Heart of Chaos, realizing he played into Caius's scheme.

As revealed in the secret ending, "The Goddess is Dead," Caius is alive and within Etro's Throne Room in the Void Beyond. He gloats how Serah and Noel unknowingly helped him create a new world where both he and Yeul are freed from their respective curses as the chaos erupts from Etro's Temple. Without Etro to hold it back the chaos within the unseen realm bleeds into the visible world through an opened Etro's gate as Valhalla manifests on Gran Pulse.

As revealed in "Lightning's Story: Requiem of the Goddess," after being defeated by Caius while getting a vision of Serah's death, Lightning finds her sister's spirit held hostage by Shadow Yeul, a chaos-based entity who was present in Serah and Noel's journey. Refusing Lightning's demand to release Serah's soul, Shadow Yeul conjures Caius to fight her while telling Lightning she is the one who caused Serah's death by sending her out to her journey. Realizing she had put her sister on the path that led to her death, Lightning is about to give up when Serah's spirit appears before her. Explaining she knew what would happen and has no regrets of making the choice to continue, Serah asks Lightning to always remember her as she promises they will meet again.

After coming to her senses in Etro's temple, Lightning's hope for the future is renewed. As the chaos blends Gran Pulse and Valhalla, Lightning ascends to the goddess's throne and transforms into an indestructible crystal epitaph to preserve the world's existence in Etro's place along with Serah's memory, waiting for a time at the end of eternity when she will awaken and be reunited with her sister. In a secret post-credits scene, Lightning wakes up in a distant future to find a dying world.

Paradox endings

 * A Giant Mistake: Both sides of the Pulsian civil war, which will eventually bring down Cocoon's pillar, unleash an army of Atlases on the Archylte Steppe. Serah and Noel are trapped in the middle of the war and resolve to take down each one. The last shot is of a downed Atlas with both Serah's and Noel's weapons lodged in an unbroken crystal atop the beast's head.
 * Mischievous Mog's Marvelous Plan with Flan: Noel and Serah use magic to disguise themselves as a Microchu and Miniflan to remain unnoticed while Mog helps them prepare a poisonous pudding to kill the evil Royal Ripeness, who has taken over the Sunleth Waterscape and wants to transform Cocoon into a human-free world of monsters.
 * Vanille's Truth: In a time after the War of Transgression, Serah and Noel find a crystallized Vanille in Oerba and promise to find Fang for her.
 * Test Subjects: Serah, Mog, and Noel are modified by the Proto fal'Cie Adam to serve as guards in the Augusta Tower. They briefly wonder what they were supposed to be doing before their memories were erased, which prompts Adam to question whether there are paradoxical aspects in the souls of every human.
 * The Future is Hope: Snow appears in Academia 4XX AF with a security detail that arrests Alyssa, preventing her from giving Serah and Noel the booby-trapped artefact from Caius. Snow warns Hope of his imminent assassination coming in three days and tells Noel to stay behind to guard him. He states he has thirteen crystals to find throughout time before flying off with Serah and Mog on Shiva as Noel and Hope look on.
 * Beneath a Timeless Sky: Serah, Noel and Yeul are trapped in New Bodhum in 700 AF, looking for a way out. Yeul can no longer see the future due to the timeline's collapse. A meteorite lands outside the town in a similar place and manner as the one in 3 AF, and they run off to investigate.
 * Fate and Freedom: Serah remains in her eternal dream with Lightning, Snow, and the members of NORA in New Bodhum, though she feels it will never be perfect without Noel and Mog, both of whom she can only faintly remember.
 * Heir to Chaos: Noel inherits the Heart of Chaos from Caius and succeeds him as Yeul's Guardian. As Noel floats through the Historia Crux he looks through Caius's inherited memories and resolves to save Yeul, Serah, and Caius from their fates.