Originally Posted by no, really!?
Jecht --
Zanarkand: visited it as ruins with Braska
Dream Zanarkand: he, over time, developed as a natural evolution of the dream of the Fayth, unexplained origins if any
Spira: he went a wee to far out to train one day, and Sin brought him to Spira (by accident), as a consequence, Jecht became "real" is the sense of interacting with Spira, and not just DZ, disappears as a result of him being killed (although he would have most assuredly disappeared if he had not been killed by the time the Fayth stopped)