Vexen
Vexen is number IV in the Organization. He is the research scientist of the group and loves to study the secrets of the heart. He is often very stoic in his behavior. Vexen is ranked higher than the others in Chain of Memories. He can control the power of ice and carries a large shield in battle that blocks any frontal attacks made against him. His fighting style typically revolves around hindering Sora's movement, and when he is fought in Twilight Town, his attacks include sending icicles to chase Sora, creating slippery frozen puddles on the ground and freezing Sora in a block of ice.
In Chain of Memories, he appears to help in Marluxia's plot, but is actually siding with Zexion and Lexaeus. He first battles Riku in order to gather data to create a replica of him. However, Vexen cared nothing for his "experiment" and allows Naminé to manipulate the Riku Replica's memories against his wishes. When the Riku Replica fails to defeat Sora, Marluxia and Larxene send him out to eliminate Sora personally. Vexen, who already has suspicions about Marluxia, is shocked by this. Marluxia and Larxene also has suspicions about Vexen's loyalty to them.
When he encounters Sora, Vexen says that he came to collect his "debt" and provokes Sora's anger by making him believe that he controlled Riku rather than created a replica. After their battle, Vexen gives Sora the card to Twilight Town with the intention of revealing something important to the boy. Marluxia considers him a traitor as a result and sends Axel to kill him, suspecting that he will reveal the existence of Roxas to Sora.
In Twilight Town, Vexen attempts to reveal to Sora why he feels as though he has been to Twilight Town despite being fairly certain that he had never been there. Sora and Vexen battle again after Vexen tells Sora to throw away his memories and listen to his heart. After being defeated, Vexen sees Sora as a true threat; even after being weakened by false memories, Sora remained very strong. Just as Vexen is about to reveal to Sora Marluxia's plot to use him and Roxas' presence, Vexen is struck from behind by one of Axel's chakrams. Vexen was the first member of the Organization to be destroyed.
