If you don't have the strategy guide that came with the Collector's Edition of Final Fantasy XIII-2 , you're not privy to this information.
…and depending on where you are in the game, you may not want to be. Bear in mind- STORY SPOILERS AHEAD!!!
…okay to keep reading?
Evidently, two pieces of upcoming downloadable content have been revealed in the guide. First, in an interview, FFXIII-2 lead writer Daisuke Watanabe said that extra content would address the sudden appearance of Sazh and Dajh in the game's ending. Said Watanabe:
"At some point, Sazh and his son Dajh got caught in Serendipity, but they came out alive having won a gamble of fate. The full details of this story will be revealed in a planned DLC release."
In addition, it seems we'll learn more about the mysterious throne of Etro, which is seen during the opening sequence (Lightning is kneeling in front of it). That throne is empty for most of the game but during the climax:
"However, in the ending, Lightning sits on the throne. This symbolizes that the world's very existence relies on her to embody the divine will. As Lighting wants to maintain hope, she enters the crystal stasis in order to protect the will of her sacrificed sister, Serah. We are planning a DLC release to reveal the background of this."
Square Enix has said in the past that they're committed to giving fans lots of great DLC for FFXIII-2, and that includes the chance to add Lightning to your party…provided you can beat her in the Coliseum. More info to come.
Related Game(s): Final Fantasy XIII-2