Vexen was the highest ranking member of the Organization inside Castle Oblivion, but ironically he is the first Organization member to be eliminated. He created the Riku Replica and uses it to carry out several experiments on Riku himself and Sora. He also appears in Kingdom Hearts 358/2 Days as a playable character in Mission Mode.
He was No. 4 in the Organization. He, Lexaeus, and Zexion have been in the group since its inception, and there is no love lost between them and neophytes like Marluxia. After battling Riku, Vexen turned to events unfolding aboveground, but successive failures led to his termination by Axel.
In Kingdom Hearts: Chain of Memories, Vexen has parts in both Sora's and Riku's storylines. He assists Lexaeus and Zexion in their efforts to stop Marluxia (whom Vexen loathed) and Larxene (whom he was not too fond of either) from overthrowing the Organization (Axel, the other Organization member residing in the castle, is deemed too unpredictable to be anything other than a liability). To do this, Vexen and his cohorts intend to use Riku's darkness to counteract Sora's light.
Vexen engages Riku in a cautious battle and uses the data he obtained from the fight to create a copy of Riku that lacks a heart. The replica is completely aware of his status as a fake, but unlike Riku, is not afraid to use the darkness. However, even with darkness on his side, the replica fails to defeat Riku. Even with the failure, Vexen has other plans for the replica, and goes to Marluxia and Larxene. He offers the replica to test Sora, though first he would have to have his memories changed around. They then have Namine manipulate the replica's memories until he thinks he is the real Riku. He also believes that he made a promise to Namine like Sora had, and because of this conflict, the replica confronts Sora multiple times, saying that Naminé no longer needs Sora.
Though Larxene and Axel also make brief appearances in the cutscenes of Reverse/Rebirth, Vexen is the only Organization XIII member in Chain of Memories who is fought as a boss in both Sora and Riku's stories. In Riku's story, Vexen confronts Riku on a mission to gain data on Riku without him noticing. When the battle is over, Vexen reveals his true objective and reminds Riku of the Darkness inside him. Vexen flees, taunting Riku. It is later revealed that the "data" Vexen received from this battle is what created the Riku Replica. Vexen is never seen again in Riku's story, but it is mentioned by Axel and Lexaeus later on that he has indeed been slain.
However, they soon lose control of the replica, and Marluxia deems Vexen's experiment a failure. Vexen is insulted, saying that a novice like Marluxia has no right to speak to an elder like himself. However, when Marluxia makes the threat of reporting Vexen's failure to "Xemnas the Superior", Vexen's fear of the Superior's power overrides his previous elitist attitude. Now with Vexen under his grip, Marluxia manages to persuade Vexen to eliminate Sora.
Vexen then confronts Sora, saying that Sora is in debt to him for reuniting him with Riku. Sora is angered, and the two battle. However, as they fight, Vexen delves deep into Sora's heart, and creates a world card forged from the memories in the other side of his heart. Vexen tells Sora that if he wants to truly defeat him, then he must enter that world.
Meanwhile, Marluxia, Larxene, and Axel note that Vexen is jeopardizing their plans, for if Sora discovers the other side of his heart, then he will no longer be of any use to them. They then send Axel to eliminate Vexen during his battle with Sora, before Vexen tells Sora of their plan.
Sora discovers that the new world is Twilight Town, which is strange because Sora has only visited places in his memories, and he has no memories of Twilight Town. Even so, Sora feels a sense of familiarity from this place. He explores the town until he arrives at the gates of a mansion. Vexen makes his appearance there, asking Sora if the familiarity of this place or his memories of Namine are true. Sora doesn't understand what he means, and Vexen sees that he is but a slave of his memories, just like "his Riku". Sora is again angered, and battles Vexen one more time.
Vexen is defeated again, and after seeing that Sora is too dangerous and powerful, plans to tell him of Marluxia's plot and, by extension, Roxas's existence. Before he can fully explain, Axel appears and strikes Vexen with one of his chakrams and embeds it into Vexen's body. When Vexen asks why he'd attacked him, Axel explains that he will eliminate Vexen and tells him that he can be "nothing instead of just being a Nobody". Vexen begs to be spared, but Axel replies with a heartless "goodbye" and snaps his fingers, detonating the chakram and incinerating Vexen, making him the first member of Organization XIII to fade out of existence.</p>
Vexen is one of the most prolific Organization members in battles, appearing as an opponent three times during Kingdom Hearts: Chain of Memories. He fights with a large blue shield, which he uses to fend off frontal attacks, making it necessary to attack him from behind. He is also able to use the shield offensively, akin to Goofy, but further enhances the style with the spikes lining the edge of his shield. He can use his cryokinetic abilities to blast his enemy with ice from his hand, and can call forth large chunks of ice from the ground to freeze his opponent solid.
He also has the power to create slippery ice patches on the ground, or summon icicles that rise from the ground and follow their target for several seconds. Finally, he can create an unavoidable blizzard that can be resisted only with a Card Break. In the remake, Vexen can conjure up a sword made out of ice and whack his opponent several times with it before performing a final shockwave which destroys the sword and ends the sleight.
Like several other members of Organization XIII in Kingdom Hearts: Chain of Memories, Vexen moves by levitating, sometimes several feet into the air.
In Kingdom Hearts II Final Mix, Vexen, as well as other members of the Organization that have already been eliminated, can be fought. Vexen's shield makes him completely invincible in this game, but the shield has an HP bar of its own and can be temporarily destroyed, allowing Sora to attack Vexen directly. Vexen has the additional power in this battle to create a copy of Sora's Anti form to aid him in battle.
Vexen still has his "freeze" attack where a blizzard freezes Sora, immobilizing Sora while Vexen gains data, but it can be stopped by a Reaction Command. He also has the icicle attack from before, but also returns with a new attack where he makes two spinning blades of ice and throws them at Sora. In the data battle against Vexen, he has a new attack where he throws giant chunks of ice at Sora.
Vexen also has the ability to collect and manipulate Data. This ability allows Vexen to create Replicas. Not much else is known about this ability.
In Kingdom Hearts 358/2 Days, Vexen has a Limit Break called Diamond Dust. During Diamond Dust, Vexen summons three large mounds of ice to come up from the ground to strike enemies, dealing ice damage to and freezing all struck enemies. Enemies that are frozen take three times as much damage while frozen.
During Vexen's Final Limit, Vexen's three mounds of ice are replaced by one larger glacier. This deals greater ice damage to enemies, and temporarily makes them gradually lose HP. It also freezes them for awhile.
Initially appearing as a powerful foe to Sora, Vexen is revealed to be one of the weaker members of Organization XIII alongside Demyx. This is indicated by the fact that no one in the Organization seems to show Vexen any respect despite his high rank. Marluxia and Larxene seem to frequently poke fun at him with jokes and sneers, with Larxene going as far as to call him a "half-baked good for nothing".
Vexen is also easily eliminated by Axel, who fought evenly with Marluxia. In Riku's story, Vexen seems to be below Zexion and Lexaeus in terms of authority, as he is the one doing all of the work while the other two hide in the basement and direct him.
WeaponVexen, like Goofy, carries a shield into battle. His shield Frozen Pride is pointed, and is colored blue and silver. He can use it to block attacks, but it is also used to slash foes. If turned upside down, the shield has the vague shape of the Nobody symbol.
In Kingdom Hearts Re:Chain of Memories, it can be changed during the sleight "Slide Break," where he freezes ice onto the shield to form a gigantic ice sword that he wildly slashes with before smashing the blade onto the foe. However, his Absent Silhouette does not use it to attack, instead relying on his data replicas and ice magic for his offense, and uses his shield to block any attacks during battle. However, the Silhouette's shield has its own small health bar, and breaks after a while, and leaves him vulnerable until another shield is summoned.
In Kingdom Hearts II Final Mix, Goofy can obtain a similar shield through synthesis.
Role in the series
Vexen was actually in due progress of being resurrected by the Villain League under Junjie's watch. This was being done in a resurrection temple under League control, where Xemnas had planned to have Vexen's logical intelligence be of a great asset to them. However, Axel, Xaldin, Larxene, and Marluxia, thanks to a tip-off from Saix, ambushed the resurrection party under Junjie's watch. The ambush was a success, with a destruction of the resurrection temple, and Larxene scaring Junjie into lying that resurrecting Vexen was a hideous failure, earning him disfavoring status from the Xehanort group. Meanwhile, Vexen, who was successfully brought back, was reluctant out of fear and personal hatred to return to three convicted traitors, and the one who caused him to be dead to begin with. However, Axel won him over eventually when he told him of Xehanort's secret plan, and Vexen deemed it to be the work of a raving lunatic, and only agreed because of logical reasons. He is among the Nobodies skeptical of the Lodgers' abilities to truly stop Xehanort's Great Cycle plan, but is curious about what they're capable off.