In Kingdom Hearts II
Hades becomes increasingly frustrated in his attempts to defeat Hercules, since the hero kills every opponent the Lord of the Dead throws at him. At Pete's suggestion that he "Send somebody already dead and save him the trouble," Hades decideds to bring out the "mother of all bad guys." He goes to the deepest dungeon in the Underworld and summons Auron, offering to let him out if he kills Hercules. Auron declines and insults the God, derisively telling him that "This is my story, and you're not part of it." Hades, in a rage, attacks him just as Sora comes in, and the group escapes, battling legions of Heartless and Cerberus along the way. The dead warrior tells the Keyblade master that it seems they were fated to meet, and asks if he needs a guardian (a reference to his origins in Final Fantasy X]]. Sora politely declines and leaves.
Sometime later, Hades seals Auron's free will into a statue and forces him to fight Hercules. But once again, Sora comes through and reclaims his soul, and the four of them defeat Hades. Auron is seen during the credits fading back into pyreflies, the essence of a person's soul in Final Fantasy X.
The lines Sora hears after touching Auron's statue are lines Auron spoke during his past before Final Fantasy X, re-recorded for Kingdom Hearts II.