As you may suspect, that would be Oerba Dia Vanille (or just Vanille), who has apparently awoken from a deep sleep with a special new power.
Square Enix also revealed the ?Outerworld service? online social component.
Lightning Returns: Final Fantasy XIII – Vanille, Outerworld service screens:
As Vanille opened her eyes from her long sleep, she realized she was given a special gift; she could hear the voices of the dead. Dubbed the ?saint,? Vanille now spends her days under the Order?s protection in Luxerion.
Additionally, a new online feature, ?Outerworld service? was announced today that allows players to submit snapshots, messages and battle scores via social media to share their exciting in-game experiences with other players.