Paddra Nsu Yeul is a Pulsian seeress hailing from the city-state of Paddra on Gran Pulse prior to the time of the War of Transgression, having written Analects relating to the event, Etro, Ragnarok, and the Eidolons. In Final Fantasy XIII-2, it is revealed that Yeul's ability to see into the future is a curse as her visions shorten her lifespan and eventually kill her in her teen years. However, Yeul is reborn in another time period and the process repeats itself. Thus, Caius made it his goal to destroy Etro in order to freeze time itself so Yeul would no longer die.
Source from Wikipeida