Young Xehanort

"Your abyss awaits."

- Young Xehanort to Riku

"You just make it too easy. I know you think you've won, but you lost the moment you dived this far in. You're in the deepest pit of slumber, and you've worn yourself down to nothing. There's no returning to the world above. We told you. It was not the Sleeping Keyholes that guided you. They are not the reason you are here. You've been on a path, one we laid out for you. That sigil on your chest is the proof. See? That sigil, the X, it tells us where you are at all times. You have wondered aloud before— why we kept showing up where you were? It's because we need you, Sora. Or, to be more precise, we need what will be left of you - the thirteenth dark vessel. Why was it assured you would come here today? Because I followed my destined path, and I'm here looking at you right now. You can move through time, but time itself is immovable. Today, all of my selves throughout time were meant to gather here, and to welcome you, Sora, as our thirteenth member. These facts cannot be changed. I have now told you all that I know. We are all here, and what the future holds in store is beyond my sight. I will return to my own time, and grow into the man who becomes all these others. While I know this future now that I have lived it, returning to my own time will erase the memories and experiences I have gained here. Still, my appointed path is now etched in my heart, which will first lead me to seek the outside world. Your heart will sleep forever in the folds of darkness. And your body will be another vessel for me. So light gives way to darkness. Good night, Sora."

- Xehanort explaining to Sora more of what he knows.

"I am Xehanort from the most distant past. My future self gave a task— to visit the splintered versions of myself in many worlds, and ensure they gathered here today."

- Xehanort revealing his true identity

Young Xehanort (also called Unknown and the Mysterious Figure) is a mysterious character, the identity of whom is actually Master Xehanort (albeit at a younger age). He first appeared in the North American, PAL, and Final Mix versions of Kingdom Hearts Birth By Sleep, in which he is fought as a super-boss and is the main antagonist in Kingdom Hearts 3D: Dream Drop Distance.

He is the original Xehanort and was given the power to travel through and manipulate time itself, to help Master Xehanort accomplish his goal of containing his essence in thirteen different vessels.

Pre-Birth by Sleep
Xehanort lived on the Destiny Islands until his future Heartless, Ansem, time traveled back in time to meet him, Ansem gave him the power to control time and sent him to gather all of their incarnations. Xehanort succeeded in doing this and later returned to his time period after Dream Drop Distance to live the life he was fated to.

Birth By Sleep
At an unknown point before Dream Drop Distance, Young Xehanort travels to The Land of Departure after his future self had destroyed it and confronts Terra, Ventus, and Aqua separately. After an arduous battle, he disappears without a trace.

Re:coded
Young Xehanort travels to Radiant Garden, where he converses with a newly revived Braig about Master Xehanort's plans. During the conversation, Young Xehanort recalls the legends of Keyblade inheritance and notes the importance of his future self's Keyblade. Braig, knowing that the weapon is tied to the Keyblade War, decides to proceed with his own plans.

Dream Drop Distance
Young Xehanort travels to the present and has several interactions with Sora and Riku. His purpose during this time is to monitor Sora and ensure he follows a path where he can be controlled. After Sora's battle with Xemnas, Young Xehanort appears and explains that Sora's Heart has already begun to sink into the Darkness and his own origins, ending with stating that since Sora's first encounter with Ansem during the original Kingdom Hearts everything that had happened was unavoidable.

Young Xehanort later appears before Riku when the latter attempts to retrieve Sora. Mickey then appears and uses a Stopza spell to freeze him, however he gets possessed by his elderly self and fights Riku. After their battle Master Xehanort appears and explains the machinations of his plans. After failing to possess Sora, the true Organization XIII's members, including Young Xehanort, return to their original timelines.

Kingdom Hearts III
Young Xehanort is set to reappear in Kingdom Hearts III.

Boss encounters
As a high-ranking villain, Young Xehanort is fought as a boss character in both his appearances to date. He is an optional "super-boss" in Birth By Sleep and the penultimate boss in Dream Drop Distance. His battles are notorious for being very difficult and confusing.

In Birth By Sleep, Young Xehanort (known as the Mysterious Figure in that game) is notorious as by far the hardest boss in the series. Here, he is fast, unpredictable, and utterly relentless in his attack patterns. Worst of all, all of his attacks can instantly kill the player in just one hit. Equipping Once More and Second Chance can prevent this, but their impact is minimal; a single hit will still knock the player to 1 HP, and even then, he never stops attacking. Even if the player manages to come up with a strategy, winning this fight requires incredible luck, skills, or both. Young Xehanort is, in fact, so hard that he was slightly nerfed in later versions of the game.

In Dream Drop Distance, Young Xehanort is much easier, but still a tough cookie. He now has a Keyblade and can use it to perform dangerous combos that can inflict Slow on Riku. When his health is almost at zero, he puts himself in a ticking clock, which Riku must quickly perform a Reality Shift on lest Young Xehanort rewind time back to the start of the fight (though he has a third of his health when he resets). When the Reality Shift is executed, Young Xehanort remains in the clock while clones of himself bombard Riku. Waiting too long to finish off Young Xehanort will result in the fight rewinding back to the start. However, when the Reality Shift is executed once more, the clock's health is how it was when Young Xehanort rewound the fight.

Trivia

 * Young Xehanort is voiced by Takanori Okuda in Japanese and Benjamin Diskin in English from Dream Drop Distance onwards. In Birth by Sleep, Young Xehanort was also voiced by Mamoru Miyano and David Gallagher, who also voiced Riku.
 * In Birth by Sleep, Young Xehanort's model is actually borrowed from Saïx's hooded model.