Vanitas

Vanitas is a character and one of the primary antagonists in Kingdom Hearts Birth by Sleep. He is the sole apprentice of Master Xehanort, the game's main antagonist. Vanitas is from the darkness of Ventus's heart extracted by Master Xehanort to further his evil plan. Vanitas's birth sparked the threat of the Unversed.

Kingdom Hearts Birth by Sleep
Four years before the events of Kingdom Hearts Birth by Sleep, Ventus served as Master Xehanort's apprentice. The Keyblade wielder was sent to the Keyblade Graveyard, where he was forced by his master to face several Heartless. Ventus lost the battle, and was knocked unconscious. Master Xehanort then proceeded to use his Keyblade to unlock Ventus's heart, resulting in an orb of dark energy forming into Vanitas. The dark enigma is also the source of the Unversed as well as a key component in Master Xehanort's plans.

After Master Xehanort viewed the battle between Terra and Aqua as part of their Master Qualification Exam, he left the room to find a hidden Vanitas awaiting him. The two conversed about Ventus, and Vanitas claimed that Ventus' performance was "not even close", and he still needed to "teach him some discipline". Vanitas later appeared before Ventus in his room, spoke of Terra no longer being himself, to which Ventus denies saying he and Terra are connected. Vanitas simply calls his friendship with Terra stupid and vanishes into a corridor of darkness, claiming that unless Ventus sees it for himself, he won't know the truth.

After his first few ventures throughout the worlds, Ventus spotted Vanitas in space and was led to the Keyblade Graveyard. Vanitas approached him, spoke of Terra losing his identity again, and challenged him to a duel, revealing for the first time he is a keyblade wielder. Vanitas gained the upper hand mid-way, knocking Ventus down. Vanitas then proceeded to kill Ventus for being at such a low level of power, but Mickey Mouse later appeared, healing Ventus. The two then proceeded to fight the dark enigma, who left yet again upon his defeat claiming he will watch over him a while longer.

After the fight, Mickey's Star Fragment sent Ventus and Mickey both to Radiant Garden. There he reunited with his friends to tackle a massive Unversed, but afterwards Terra, Ventus, and Aqua went their separate ways. While Aqua stayed behind to contemplate, Vanitas appeared and approached her, taunting her by inquiring about Ventus and if he's gotten stronger. When asked what he meant, he rudely says that he's asking the questions and attacks, the two fighting a vicious battle. After the duel, Aqua attempted to remove Vanitas's helmet, but the dark enigma startled her with an insane laugh. He then complements her skill, making an ambiguous comment about her being his plan B, and finishes it by saying "be a good girl and get stronger". Ventus overheard Vanitas's last few words to Aqua, returning to her side just as he left in another corridor of darkness. Vanitas later crossed paths with Aqua in Neverland with Ven's cherished Wooden Keyblade. The dark enigma cruelly snapped the toy weapon in two, claiming that since Ventus has gotten stronger, he no longer needs it thus Vanitas no longer needs her as his plan B. He battles Aqua once again. Leaving Aqua exhausted and enraged at the thought of Ventus being in danger, but just as soon as he had appeared, Vanitas vanished yet again in a dark corridor.

Vanitas encounters Ventus again in Destiny Islands, after the latter is thrown through a portal summoned by Terra. Vanitas tells him that since they are equal in power, they can fuse together to create the X-Blade. Ventus refuses, claiming that if he doesn't fight, the X-Blade cannot be created so he won't fight. Vanitas angrily says that he is pretty defiant for a "cast off shell". Then, in a series of flashbacks, Vanitas explained his birth from the darkness in Ventus's heart, and how he took his place as Master Xehanort's apprentice. This caused Ventus great pain in regaining his memories, Vanitas vanishing as Ventus fled the world, but not before the villain gives Ventus an "invitation" to the Keyblade Graveyard where he tells him he will see Terra and Aqua fight for the final time, and callously wonders if Ventus will just watch without batting an eye.

When Terra, Ventus, and Aqua approached their final battle with Vanitas and Master Xehanort at the Keyblade Graveyard, intense battles ensued. The two darklings met up with the Keyblade wielders, Terra charging them. Master Xehanort intervened, however, blocking Terra's path with massive rock formations. As Terra continued to pursue Master Xehanort, Vanitas went after Aqua and Ventus. The two fought valiantly against the dark warrior, but not before he returned to Master Xehanort's side after Ventus was frozen. He battled Terra alongside Master Xehanort, who later commanded Vanitas to go after Ventus and Aqua again.

Vanitas attacked Aqua from above, knocking her unconscious, and prepared the final blow while Ventus lay helpless and frozen. Ventus summoned all of his willpower, however, standing and facing Vanitas in battle again. The dark enigma revealed his face, revealing himself to be the source of all Unversed, and that he spread them across the worlds so Ventus could grow strong enough to form the X-Blade while summoning many Unversed to hold Ventus down as he forcefully integrated into him. In a burst of light, Vanitas and Ventus were transported to the Awakening, Ventus's pillar now hosting a picture of Vanitas, as well. Vanitas wielded an incomplete version of the X-Blade.

Vanitas claims their fusion was incomplete, and they only managed to make most of the X-Blade. He then tries to re-intergrate into Ventus once again, but Ventus refuses, vowing to defeat Vanitas and destroy the X-Blade. The dark enigma simply laughs, confident in the fact that they both know that if the X-Blade is destroyed, so would Ventus' heart. But Ventus rebukes him, saying he will fight for his friends no matter what, even if the price is his heart. Vanitas mockingly asks "so its the whole for my friends' sake thing again?". Ventus says that a dark being like him could never understand friendship, and finishes his statement by saying "Our connected hearts are my power!", and the two keybearers face off for the final time.

As Ventus battled Vanitas in their Awakening, Aqua and Mickey were forced in the physical world to battle a sort of Ventus/Vanitas fusion, which was Ventus's form with Vanitas's golden eyes and bodysuit. Vanitas/Ventus summoned the completed X-Blade, and exclaims with psychotic glee that he plans to unlock Kingdom Hearts and restart the legendary Keyblade War. He then attacks the duo. As Aqua defeated her possessed friend and destroyed the X-Blade, Vanitas's metaphysical battle with Ventus came to an end after they shattered the pillar on which they fought, with Vanitas fading out of existence, taking all Unversed in existence with him and relinquishing his control over Ventus. Unfortunately, the victory is bittersweet as Ventus lost his heart and fell into a comatose state in the process.

Appearance
Vanitas wears a black and red organic-looking bodysuit, which is quite similar to Riku's Dark Mode from Kingdom Hearts and Kingdom Hearts: Chain of Memories. He wears a silver helmet covered with dark glass, hiding his face from view. It's revealed that his face is identical to Sora's face, although he possesses golden-yellow eyes, black hair, and paler skin. In an interview with Tetsuya Nomura, it is revealed that this similarity is due to Sora's heart connecting with Ventus near the beginning of the game, and had anyone else connected with Ventus's heart, Vanitas would look like that person. He normally wields a Keyblade that is colored primarily in red and black, with two blue eyes like the Soul Eater, Way to the Dawn, Chaos Reaper, and Xehanort's Keyblade, but in the final chapters, he gains the X-Blade, and also fuses with Ventus, resulting in him looking like Ventus wearing the dark suit.

Personality
As a being created from the purest of darkness, Vanitas is proud, cunning, cruel, and pure evil. The lives of others, including that of even Master Xehanort, hold absolutely no value to him, and as a pragmatist, he would strike without a moment's thought or warning. His overall personality is in an extremely stark contrast to Ventus and Sora (and, by extension, Roxas and Xion) who are valiant, value friendship, and possess heroic qualities.

Fighting Style
Vanitas is a skilled warrior with the Keyblade and magic. He is seen casting fire, thunder, and blizzard magic, performing complicated acrobatics, and even rides the flying Keyblades that Master Xehanort sends out. Vanitas also counterattacks if he is struck multiple times, making him difficult to fight in close combat. Also, Vanitas's battle stance greatly resembles Riku's battle stance. It also seems that Vanitas can be summoned by Master Xehanort by force of will. When he summons his Keyblade, it appears in a flash of purple fire.

Trivia

 * After his first spoken line, Nomura made a joke saying that he was to voice Vanitas. Nomura also stated in another interview that Vanitas's identity was familiar and perhaps also shocking. It was later revealed that Vanitas was voiced by Miyu Irino, the Japanese voice actor for Sora. According to Tetsuya Nomura, Irino had said for a while that he wanted to play an evil character, and Nomura jokingly stated he sort of got carried away with it.
 * Vanitas's name is derived from the Latin word for "Vanity" or "Emptiness", and was chosen for its meaning, that it sounded similar to "Ventus", and that it was a written pun on "Sora" in Japanese."Tetsuya Nomura: I wanted to give him a name that meant 'empty', and so I looked for something that would be appropriate. When I was searching I found a word that meant 'emptiness' in Latin, 'Vanitas'. It looked a lot like Ventus's name, and in Japanese it has the kanji for 'sora' in it, so I thought it was perfect. Of course in Vanitas's case it doesn’t mean 'sora [sky]' but 'kara [empty]' [These two words are written with the same kanji, but are said differently and have different meanings.]"
 * Only Master Xehanort and Ventus have seen Vanitas's face.
 * Kingdom Hearts Birth by Sleep Ultimania refers to him as the Masked Youth (仮面の少年).
 * Out of all the antagonists to appear in the series, Vanitas has been fought in the most boss battles, a total of seven battles in all.

Notes and References
Vanitas