Vile Peaks The Vile Peaks is a location in " Final Fantasy XIII " and an optional location in " Final Fantasy XIII - 2 " . It is a range of mountainous peaks in Cocoon formed mostly of scrap metal . After the War of Transgression , supplies were raided from Gran Pulse to repair the damage Cocoon had sustained . The junk was dumped at the Vile Peaks , and thus the junk - filled terrain contains dilapidated Pulsian machines who continually fight the lingering Cocoon robots . The Vile Peaks is an unrevisitable location in " Final Fantasy XIII " and comprises the fourth chapter of the game . In " Final Fantasy XIII - 2 " , visiting Vile Peaks is optional , and it is unlocked in the Historia Crux by finding the correct artefacts . Datalog . " The Vile Peaks are built of debris — the castoffs of material originally lifted up from Pulse by the fal ' Cie and used in the construction of Cocoon and later additions of landmass . These towering piles of refuse now serve as lairs for all manner of beasts , including lowerworld mechanical horrors that , intentionally or not , hitched a ride with what became the building blocks of Cocoon . The Sanctum military endeavors to clear out the dangerous inhabitants of the peaks , but some say they leave the job half done to discourage civilians from entering the lowlands . " " Located in Cocoon , Vile Peaks is a massive dumping ground of waste and refuse . When the fal ' Cie built Cocoon , and during later modifications , large quantities of material were lifted up from the surface of Gran Pulse . " Fragment s . " The unused surplus was discarded here , and now it is infested with roaming war machines of ancient Pulse . " " Forget about sightseeing . Not even the military is allowed full access . That said , there are a few brave collectors of retro war weapons and relics who sneak in here to scavenge for parts . . . " Story . " Final Fantasy XIII " . The newly branded l ' Cie arrive at the Vile Peaks after crashlanding the airship they boarded at Lake Bresha . After Lightning gets fed up with the others over their lack of stamina , the party splits , with Lightning and Hope separating from Sazh and Vanille . Lightning explains to Hope why she volunteered to join the Purge , but soon leaves him . Sazh and Vanille find Hope and regroup with Lightning . After a fight with a Dreadnought the party tries to discern their Focus . Lightning feels that instead of completing their Focus , they should travel to Eden , Cocoon ' s capital , to destroy its patron fal ' Cie . After a disagreement , Lightning and Hope split from Sazh and Vanille , this time permanently , as a PSICOM attack prevents them from regrouping . On their way out Lightning and Hope find another Dreadnought , and Hope rides it , powering through ranks of enemies . Lightning summons Odin out of anger for having to " babysit " Hope and after the two defeat the Eidolon , Hope vows to become stronger , and Lightning lets him stay with her . Sazh and Vanille make their way through a trash repository , reactivating its power . With no plan in sight apart from escaping PSICOM , they settle to sleep on the ground for the night . " Final Fantasy XIII - 2 " . Lightning blames herself for causing the paradox that caused the Academy anti - paradox team , the Blitz Squadron , get lost in time while scouting the area in 10 AF to deal with a distortion . She appears in the area at 10 AF , just before Serah , Mog , and Noel engage the paradox , a dark imitation of Odin called Twilight Odin . In 200 AF , after they defeat Twilight Odin ' s true form , Lightning is released from the burden of Odin ' s shadow twin . She recalls fighting alongside the men in Blitz Squadron and finds comfort in how they still remember her . As Lightning watches Noel and Serah from afar , she tells her , " So , Serah . If you keep me in your thoughts , one day , I am certain I will find my way home again , " to which Serah answers that she will . Serah , Mog , and Noel meet Sazh seemingly caught in a paradox who tells them he is gambling for the thing most dear to him in a mysterious place . Later , when Mog reveals a phased - out image of Lightning , she tells Serah and Noel about how as a l ' Cie , she first thought fighting for what she believed in alone was the only way but was proven wrong by realizing she wasn ' t alone since the others were burdened with the same fate . Now all by herself in Valhalla , Lightning holds on to the memories of Serah and her friends to stay strong in her battle against Caius Ballad . She tells Serah that she misses her and prays for the day when they can be together again , and disappears . Areas . The area is largely untouched in " Final Fantasy XIII - 2 " , although had been reduced in size to the beginning state from Chapter Four of " Final Fantasy XIII " where the travel limits to circling around the area . The mechanical engines are absent , also disabling travel to the upper parts of the Peaks . Treasure . " Final Fantasy XIII " . Pulse Armament Treasures . During the trek through the Scavenger ' s Trail , Hope takes control of a Pulse armament to clear out a path of Pulsework Soldiers . At the end of the minigame , two treasure spheres will appear whose content depends on how many Pulsework Soldiers were defeated in total and how many were defeated with the sweep attack . Musical themes . The Vile Peaks ' eponymous theme plays as a background theme in " Final Fantasy XIII " with " Sazh ' s Theme " playing in the Scrap Processing zone . The Vile Peaks theme reappears in " Final Fantasy XIII - 2 " being played in the Archylte Steppe during cloudy weather . At 200 AF , " Blinded By Light " serves as the background theme . A number of other themes are used in this area at various points in " Final Fantasy XIII - 2 " depending on the completion of certain story events , such as " PSICOM " and " Lightning ' s Theme " .