He was brought to Spira the same way as Tidus. Sin came & nabbed him while he was on the beach.

I kind of have a theory about X. I don't think Tidus was the dream, but Spira was the dream. Jecht abandoned Tidus @ a young age, & Tidus feeling loss, had this weird dream where his father went off to be a hero & turned into a monster.

As was said in the game, his mother did die of a broken heart & Tidus did become a Blitzball star, but the attack on Zanarkand & the whole adventure was all fabricated.

His cohorts in the adventure all represent something Tidus needed to cope w/ his father's absence. Auron was the father figure, Lulu mirrored his mother (as she had to cope w/ losing the love of her life), Wakka represented the stages of grief denial & bargaining (he denied the loss he felt & in a way tried to replace Chappu w/ Tidus). Kimahri represent the feeling of inadequacy. Rikku, like Tidus, was w/o a father figure. Finally Yuna represented the struggle of overcoming her lot in life.

Lulu & Wakka eventually came to accept the loss of Chappu. Tidus would accept the loss of his parents.
Kimahri gained honor & his self respect by defeating his bullies. Tidus would do the same after defeating his father.
Rikku accepted her father for who he was. Tidus would do, but only because the dream made his father to be something of a martyr.
Yuna not only accomplished her mission of retrieving all the Aeons, she was able to defeat Yunalesca & Sin w/o having to repeat the same vicious circle & survived. Tidus whole journey wasn't to defeat Sin, but to come to terms w/ his father leaving, his mother dying & to learn to cope w/ it.