While Vanitas acts based on his own desires, it appears that Master Xehanort can summon him at will.
When fighting her for the final time, Vanitas taunts her by sarcastically asking if she has given up, and boasts that Aqua was just "wasting her energy" trying to stop him. Vanitas later appears before Ventus in his room, speaking of Terra being a Vanitas then travels to different worlds, spreading his Unversed across them in hopes of making Ventus strong enough to forge the χ-blade. Vanitas in Kingdom Hearts Birth by Sleep. With the χ-blade, Vanitas becomes even more formidable, with his strength and attack range greatly multiplied and being able to skillfully use it to perform powerful moves, incorporating his teleportation to unleash swift attacks from all sides and also bombarding with several rapid jabs while cloaked by darkness.
Unfortunately, it is a pyrrhic victory, as Ventus loses his heart and falls into a coma in the process.
Master Xehanort intervenes, however, blocking Terra's path with massive rock formations. Though he typically uses the Corridors of Darkness to travel, it is shown that Vanitas is freely capable of surviving in and navigating the Lanes Between unaided by surrounding himself in an aura of dark energy. Ventus and Sora try to resonate with Vanitas in hopes of redeeming him, only for the latter to reject this offer. So...why shouldn’t you and I look exactly the same? Vanitas is an extremely powerful and ruthlessly pragmatic fighter, easily punishing an opponent's opening or dodging out of the way at the last second. Vanitas' brief appearance as a vision via Ventus' heart.At some point prior to his destruction, Vanitas's heart was collected by Vanitas's heart appears within Young Xehanort in the Realm of Sleep, talking to Vanitas, now wearing a black coat, gathers with the rest of the real Organization at As his time was up without a proper vessel in the future, Vanitas's heart was returned back to its original place in time, though he, along with the other time-traveling members of the real Organization, soon reassemble in the future.
Though he typically uses the Corridors of Darkness to travel, it is shown that Vanitas is freely capable of surviving in and navigating the Lanes Between unaided by surrounding himself in an aura of dark energy. Ventus was unable to use his darkness, and was knocked unconscious by the Heartless. When Terra, Ventus, and Aqua approach their final battle with Vanitas and Master Xehanort at the Keyblade Graveyard, intense battles ensue. The envy he feels against them is seen in his frequent criticizing of Ventus's friendships with Terra and Aqua, when he callously breaks Ventus's wooden Keyblade while cruelly antagonizing Aqua for playing with the Lost Boys, his constantly calling Ventus "idiot", and forcing Ventus to fight him by threatening to eliminate Terra and Aqua after Ventus refused to. Vanitas reveals that the Unversed originated from his dark emotions.Vanitas claims their union was incomplete, and they only managed to make a fraction of the χ-blade. He even has his own personal Shotlock dubbed the “Vanitas possess inhuman swiftness and speed, able to perform complicated and nearly impossible acrobatic feats such as jumping off of a high cliff while landing squarely on his feet, and even riding a cloud of flying Keyblades.
Vanitas attacks Aqua from above, knocking her unconscious with a devastating blow, and prepares to impale her through the chest while Ventus lies helpless and frozen. He is also shown to be an uncaring, cold, and ruthless individual, having not the slightest sympathy for anyone but himself. Ventus interrogates him about what he meant about Terra being a different person.