Xehanort's Guardian

Xehanort's Guardian is a dark symbiote that shares many features with Pureblood Heartless. It is first summoned by Ansem, Seeker of Darkness throughout the Kingdom Hearts series. It is first created by Terra-Xehanort, Ansem's original persona, before his final battle with Aqua in Radiant Garden. The Guardian is also used by Riku when he takes on the form of "Ansem" during his battle with Roxas. The Guardian serves not only to protect its host from attacks, but also to fight for him when needed.

Kingdom Hearts Birth by Sleep
Having lost to Aqua in their first battle, Terra-Xehanort's great rage causes the Guardian to spawn behind him. The Guardian also raises a barrier for Terra-Xehanort to cage Aqua in to continue fighting. The dark entity then teams up with its progenitor to challenge Aqua one final time. Upon Terra-Xehanort's second defeat at Aqua's hand, Master Xehanort attempts to force what remains of Terra's heart out of him by unlocking his heart once again.

However, the Guardian reappears behind him and begins to fade, opening a portal into the Realm of Darkness, into which it and a severely weakened Terra-Xehanort helplessly falls in. Aqua then dives in after them and sacrifices both her armor and Keyblade to save Terra's body from the darkness, taking his place.

Kingdom Hearts
After conversing with Sora over the true nature of the heart, Ansem, Seeker of Darkness proceeds to summon his original persona's Guardian, preparing to battle Sora due to the Keybearer's naïvety. The Guardian later appears alongside Ansem during his second battle with Sora, again transforming and increasing in size to become part of the World of Chaos. The Guardian, along with the rest of the World of Chaos, is destroyed at the hands of Sora, Donald, and Goofy after the climactic battle.

Kingdom Hearts: Chain of Memories
After Riku emerges from the twelfth basement of Castle Oblivion, Ansem, Seeker of Darkness appears before him and attempts to retake his body. However, Riku chooses to fight rather than submit, enraging Ansem, who summons his Guardian and attacks.

Later, Riku reaches the first basement of Castle Oblivion and uses Naminé's Castle Oblivion World Card to bring forth Ansem. Ansem creates around them a facsimile of Kingdom Hearts itself, and again summons the Guardian, who attempts to crush Riku with a swing of its fist. However, Riku is able to defeat both Ansem and his Guardian, and he emerges from the battles having conquered his inner darkness.

Kingdom Hearts 358/2 Days
Realizing his loss to Roxas is inevitable, Riku unleashes the dark power that is Ansem, Seeker of Darkness that he had been holding back from within his heart. Riku (in the form of a pseudo-Ansem, Seeker of Darkness) uses the Guardian to grab Roxas by the shoulders and squeeze him to the point of unconsciousness. This then allows Riku to take Roxas to DiZ as assigned, the only downside being the fact that he is stuck in the form of Ansem, Seeker of Darkness.

Kingdom Hearts 3D: Dream Drop Distance
The Guardian once again appears alongside Ansem in the sleeping worlds. As before, Ansem uses it in his battle with Riku inside Sora's dreams. After Riku defeats him the first time, Ansem sinks into a giant ball of darkness that is connected to the Guardian, in an action similar to Sora's battle with World of Chaos.

Later, when Riku, King Mickey and Lea attempt to save Sora from becoming Master Xehanort's thirteenth vessel, Ansem summons the Guardian to strike at Riku and Mickey. Before it can, however, Donald and Goofy arrive, having used Mickey's Star Shard. The two land comically on the Guardian, forcing it to disappear.

Abilities
The Guardian has many dark powers with which it assists the one it is paired with in battle. It also possesses great physical strength and is impervious to all damage. While it tends to stay behind its host, it can be commanded to detach itself from that host to attack its victims. It has the ability to possess its opponents in order drain their HP and hold them in place to give its host an opening to attack. The Guardian can also attack with bursts of darkness, fire, and lightning spawned from its fists, darkness-infused punches, and blades of dark energy.

Similar to a Pureblood Heartless, the Guardian's most devastating ability allows it to sink into the ground, creating massive shockwaves every time it re-emerges in an attempt to grab its opponent. The Guardian and its host can also double-team opponents as it uses its own body to ram them with brute force with its host safely steering it from behind while protected by a shield of darkness.

When merged with the World of Chaos form, the Guardian becomes more of a defense mechanism than one of offense, able to summon Bit Snipers to distract opponents, drain its opponents MP as opposed to their HP if they get too close, and create large whirlwinds with its arms to knock its enemies away. While it is only when the Guardian is paired with its host that it is a truly formidable opponent, it is shown to hold its own quite well without the influence of a host, mercilessly attacking the opponent without ceasing.

Paired with Ansem (Battle I)
When paired with Ansem, Seeker of Darkness, the Guardian will immediately go on the offensive in battle, punching opponents if they come too close or bombarding them with dark projectiles if they are out of attack range. On Ansem's command, the Guardian will appear in front of him, preventing him from being damaged. However, Aeroga, or attacks such as Ragnarok, can still hit Ansem if one runs around to his location.

The Guardian may also obey Ansem's command to leave him and attach itself to Sora, a "?" occasionally appearing over Sora's head once this occurs. If is pressed when this icon is on the screen, the Guardian will latch onto Sora and drain a large amount of his HP. It will eventually return to Ansem in the end, however. It is because of this attack that the player must use careful timing of the Dodge Roll ability, as well as use Curaga when necessary. Guard can be used to earn Tech Points when Sora deflects the dark discs the Guardian shoots back at it.

Paired with Ansem (Battle II)
When Ansem and the Guardian face Sora on his own, their moveset will be identical to that of the first battle. However, the Guardian and Ansem can now use some new, devastating attacks. The first involves the Guardian and Ansem jetting across the battlefield, dealing damage as they collide with Sora. Either Guard or Aeroga can be used to halt the Guardian and Ansem. The second is, by far, the most damaging, the Guardian sinking into the ground on Ansem's command and creating short-ranged shockwaves as it respawns in an attempt to attack Sora. Dodge Roll can be used to avoid the Guardian, as well as the large burst of energy that results in the Guardian returning to Ansem.

As the World of Chaos
The Guardian will generally not attack in the form of the World of Chaos, however, it will attack by swinging its arms if Sora is too close to it. The Guardian will aid its master Ansem to create large gusts of wind to blow Sora away. It can also summon Bit Snipers, which relinquish large and much-needed HP balls when defeated.

Paired with Ansem (Battle I)
During the first battle between Ansem, Riku, and the Guardian, Ansem will only shoot bursts of energy while the Guardian bombards Riku with punches. In Kingdom Hearts Re:Chain of Memories, however, the Guardian aids Ansem as he teaches Riku how to perform a Card Duel. The Guardian will only deal punching attacks during this "battle", as well, he and Ansem not taking damage as they did in the original Kingdom Hearts: Chain of Memories.

Paired with Ansem (Battle II)
During Riku's second battle with Ansem and the Guardian, the gloves are off. While Ansem shoots bursts of energy, the Guardian will punch at Riku, collide with him as he and Ansem fly at him shining with dark energy, or even create shockwaves as it sinks into the ground and re-emerges beneath Riku, hitting him several times. In Kingdom Hearts Re:Chain of Memories, it is the Guardian who launches the bursts of energy from its fists, also using the dark projectile attack from Kingdom Hearts. The shockwave desperation attack also has the added energy burst effect seen in Kingdom Hearts, as well.

Paired with Terra-Xehanort
When paired with Terra-Xehanort during the final battle with Aqua, the Guardian will do most of the attacking, creating small shockwaves as it re-emerges from dark portals on the ground, slamming Aqua into the ground after carrying her high into the air, should the shockwaves make contact with her. The Guardian can deal a powerful punch, release twin columns of energy from its fists, and even shoot twin energy spheres from each hand.

The Guardian can latch onto Aqua, the Keyblade Master only able to free herself when the player rapidly taps ; when this happens, regardless of whether or not Aqua frees herself, it will warp Aqua to Terra's mind. The Guardian will attempt to drive Aqua away from Terra (who waits for Aqua to activate Dual Limit) with its energy sphere attack, but if she gets past it and makes it to Terra's location, she can activate a special Deck Command called Dual Limit that will deal impressive amounts of damage to the Guardian by allowing Aqua to team up with Terra and shoot it with an immense amount of light energy. Hitting the Guardian with any attack or magic spell during this phase will force Aqua out of Terra's mind.

Paired with Ansem (Battle I)
Whilst paired with Ansem, the Guardian uses the same moves as it did in Kingdom Hearts, namely the powerful charge attack, the ability to be used as an impenetrable shield, and the power to fire dark bolts of energy from its hands.

Paired with Ansem (Battle II)
In this battle, the Guardian becomes huge and connected to a large ball of darkness, in which Ansem protects himself. The Guardian can use this ball to summon a shockwave to blow back Riku. It retains the power to shoot blasts of dark energy from its hands, but also gains the power to trap Riku in an orb of energy, inflicting heavy damage whilst Riku is within this orb.

Design
The Guardian has a grey-black, muscular, humanoid body, standing at eight feet in height with a pair of long, crooked antennae coming out of the top of its head and four shorter ones coming out of the back of its head. The antennae on top of its head have wide bases and become narrower as they become longer and crooked. Its demonic head bares some resemblance to that of Master Xehanort. It has small, glowing yellow eyes, blue gums, and sharp teeth. Two bandages cross over the top of its head and wrap around its antennae while two more cross over its neck and upper back and two bandages cross over its chest with another two crossing over from its shoulders and attaching a fifth bandage wrapped to the base of its thick neck. It has a blue, heart-shaped hole in its lower torso just below its bandaged chest that is reminiscent of the heart shaped hole that appears in various Pureblood Heartless. It has a shadowy tail that connects into the shadow created at Terra-Xehanort's/Ansem's feet, giving the impression that it is his shadow.

When merged with Ansem when he becomes the World of Chaos, the Guardian becomes titanic in size, standing at approximately sixty feet tall and even more monstrous in appearance. Its antennae become a protective, esoskeletal-like helm of of long, jagged, black horns with the two longer ones in the front and two shorter ones in the back. The upper sides of its head are covered with glowing purple scales while the place were its nose was is covered with dark blue scales. The space around its glowing yellow eyes are ringed with red veins and its helm exposes its sharp teeth and blue gums.

The Guardian's arms are longer than it itself is and are covered by what appear to be wide, ragged sleeves that are dark blue at the hem, fade into dark purple at the middle, and are dark green around the elbows. It has two pale yellow "eyes" on its armored chest and a bulbous blue growth lined with thin silver veins on either shoulder. The Guardian's overall appearance is more repulsive, with its upper back muscle, ribs, and vertebra exposed. A yellow ring is connected into its upper back while a similar tube wraps around its shoulders to attack two red, demonic, reptilian heads to the front of its shoulders.

The heads' mouths open up and fill with dark energy when the Guardian prepares to fire an orb of darkness from its own mouth. Its entrails consist of a thick, black cable and six thinner ones with red bases that come out of the lower part of its hollow torso and connect into Ansem's back. The Heartless emblem once worn by Ansem is now attached to these cables which Ansem can use to seal himself while resting inside the Guardian's chest cavity. The Guardian's tail is now fused into the top of a orange hollow surrounded by fleshy red mound shaped like a heart with two long pink pillars extending up from it, creating a pilot's seat of sorts.

In the second battle with Ansem in Dream Drop Distance the Guardian takes on a new form. It encases Ansem in a sphere of Darkness with itself attached to the top, and a pair of wings flanking the side of the sphere.