Clear
Chapter Thirteen
First entry taken from the game's datalog.
The Cradle Will Fall
The Cavalry soldiers set on overthrowing fal'Cie rule now wander the halls of the Sanctum as monstrous Cie'th.
Barthandelus never intended for them to reach Orphan. It was merely a ruse to spur the reluctant l'Cie into action. Though the companions refuse to complete their Focus, he no longer needs to manipulate their minds.
All that remains is to crush any hope they have for their future. When that hope turns to despair, one of them, consumed by anger and regret, will transform into Ragnarok.
And the beast — an unstoppable incarnation of wrath — will slay Orphan. Cocoon will shatter, and the energy released by the deaths of millions will summon the Maker.
A new dawn approaches...
It is for this day that Barthandelus built Cocoon, tended to its people, and watched over the servants of the Pulse fal'Cie. He gives one final order to the fal'Cie Eden: guide the steps of the cursed l'Cie. Bring them to the one who dreams of death.
Bring them to Orphan's Cradle.
Ending
The game only has one datalog entry for Chapter 13 — which is annoying when you embark on post-story objectives and you're stuck seeing the first summary every time!
A brief summary of the ending: the l'Cie fight their way to Barthandelus, who merges with Orphan and is a pain in the ass to defeat. When Orphan is defeated, Cocoon begins to fall, and Vanille and Fang turn themselves into a crystal pillar that encases Cocoon and keeps it from crashing to the ground. The other l'Cie are turned to crystal, but a light shines from within Cocoon and they're set free. (This "light" is expanded on in FFXIII-2, but is an unknown entity in FFXIII.)
Lightning and Snow reunite with Serah, and Sazh reunites with Dajh. Lightning gives her blessing to Snow and Serah's wedding, and smiles.