Lightning, star of Final Fantasy 13, can be made a party member in sequel Final Fantasy 13-2.
Japanese magazine Weekly Famitsu (via Andriasang) reveals Lightning will appear as a DLC coliseum character in the game. Defeat her, and you can add her to your party. The coliseum battle mode includes classic Final Fantasy series bosses - Sephiroth?
Elsewhere, Square Enix plans to release "secret story episodes" for Lightning. The Japanese company will also release Final Fantasy 13-2 novels with a view to expanding the story outside of DLC. Sazh, his son and the Chocolina character will be included in DLC or novels.
13-2 is out in Japan now. It launches in Europe on 3rd February.
Lightning and others will be classed as 'monsters', so you can't change to them for the party leader.
With the other DLC, why am I not surprised? I hate it when companies make you pay for DLC that adds onto the story.