It's been 19 years since complicated FFX storyline.
Tidas finds himself 1000 years in the future after being attacked by a monster known as Sin in his home city of Zanarkand, which is now in ruins. He s with Summoner Yuna, who is following in her father, High Summoner Braska's, footsteps to complete a difficult pilgrimage to defeat Sin. Each time Sin is defeated, a period of peace known as the Calm exists until Sin reemerges, and this cycle has gone on for a millennia. Braska was the last Summoner to defeat Sin with the help of Auron and Jecht, Tidus's father.
Auron explains that Jecht is now Sin. Tidus eventually learns he, his father, and his Zanarkand are all dreams summoned by the fayth — self-sacrificed spirits of humans who merge with pyreflies to manifest aeons (which can be summoned by Summoners) or other magical phenomena like Tidus and the Zanarkand he knows. Thus, Tidus is actually only as real as Yuna's aeons. The destruction of Zanarkand 1000 years ago resulted from its battle with the machina-powered city of Bevelle. Upon Zanarkand's defeat, its leader and powerful summoner Yu Yevon had his followers sacrifice themselves into fayth to continuously summon and preserve their beloved Zanarkand in a dream state. The inhabitants live and age as intended by Yu Yevon. As Tidus was a part of this, he is not an actual human, nor did he travel 1000 years into the future. However, because of the way their magic works, he did physically exist. Yu Yevon also transformed himself into Sin, destroying whatever machina he could to protect Dream Zanarkand.
Is Tidus Still Alive After FFX's Ending?
Yunalesca, Yu Yevon's daughter, was the first Summoner to destroy Sin. To do so, a Summoner must sacrifice a loved one to become a fayth to dream (summon) the Final Aeon, which defeats Sin but also inevitably combines with Yu Yevon's spirit to become a new Sin reincarnate, also destroying the Summoner. This happened to Yunalesca and her husband Zaon, as well as Jecht when he and Braska made the ultimate sacrifice to bring about the latest Calm. This explains why Jecht is Sin, as his summoned Final Aeon combined with Yu Yevon's spirit. Somehow, Jecht-Sin had enough willpower to attack Dream Zanarkand, pulling out Tidus in hopes of destroying Sin for good.
Upon reaching the present-day Zanarkand ruins, the party learns the futility of the pilgrimage from the unsent Yunalesca — who, though long dead, remains as a spirit to instruct future Summoners on how to defeat Sin. Refusing to continue the cycle of sacrifices, the party defeats her and infiltrates Sin, where they encounter and kill Braska's Final Aeon-form version of Jecht. They then find Yu Yevon's withered spirit, who possesses each of Yuna's aeons, but the party destroys them all, ultimately killing Yu Yevon and destroying Sin permanently. This also destroys Dream Zanarkand and Tidus, as they are no longer being summoned by Yu Yevon and the fayths.
The ending cinematic shows Yuna sending off Auron, each of her aeons, and Sin to the Farplane. Tidus makes a heartfelt goodbye before disappearing into the Farplane to the spirits of Auron, Braska, and Jecht. Because Tidus and Jecht had been manifested by the fayth, they are able to be sent to the Farplane like Yuna's aeons. Finally, after the end credits, Tidus is shown waking in water, emerging with a big smile.
The purposeful ambiguity of his destiny continues into Final Fantasy X-2, where depending on the player's choices, multiple endings can be discovered. The most ideal one results with Tidus and Yuna being reunited, as Tidus speculates the fayth may have gathered up his thoughts to bring him back, and he and Yuna can stay together if they promise to cherish one another. The ending of Final Fantasy X is meant to be interpreted in different ways, but hopefully this clears up some confusion.
