Larxene
Larxene, the Savage Nymph is number XII in Organization XIII, and it's only female member. She is the lowest on the Organizations numbering system after Roxas, number XIII. She played a large role in Sora's storyline during the events of Kingdom Hearts: Chain of Memories.
Castle Oblivion
Larxene was one of the Organization members assigned to work under Marluxia in Castle Oblivion, which Marluxia held as a fortress for the Organization's research into memories. Marluxia, Larxene, and Vexen conspired to usurp control of the Organization and the Nobodies from its leader, who at the time was unknown to Sora. The Organization revealed themselves to Sora slowly, at first appearing to be helpful by providing him with the means to fight within the castle (Sora had lost all of his abilities due to memory loss). Marluxia fought in disguise to instruct Sora in the use of battle cards, and Axel later fought Sora to test his strength. Larxene fought him next, with the intention of antagonizing him, and planned to "throw the fight".
After she loses the battle and speaks to Axel, Axel makes on off-hand comment about using a captive girl, Naminé, to aid them in taking control of Organization XIII. Larxene, believing Axel to be in on the plot, voices her support for it, but as she leaves, Axel remarks that she should have kept it quiet.
Vexen and Axel
Soon after Vexen battles Sora to observe him, Marluxia and Larxene begin to doubt his sincerity. They decide to compel Vexen to pursue Sora by threatening to tell "the Superior" of the failure of the Riku Replica, despite Vexen's confusion at the orders, since Sora's death would ruin Marluxia's plans to use him against the Organization's head members. Although Vexen is number IV and Marluxia number XI, Marluxia had been given authority control over the castle; this coupled with Vexen's fear of Xemnas compelled him to engage Sora in a simulated Twilight Town. Vexen failed, and planned to tell Sora about Roxas in order to break Marluxia's plans for controlling Sora. Axel cut him off by killing him just before he spoke, having been ordered to eliminate him as a traitor to the conspiracy. When Axel returned, Larxene said that they hadn't been sure if Axel would have done it; in this way, Axel earned the trust of both Larxene and Marluxia.
Death
As Sora continued to make his way toward the top of Castle Oblivion, both Larxene and Marluxia left Naminé to be guarded by Axel. Axel allowed her to escape. Shortly afterwards, Larxene appeared before Sora after he had defeated the Riku Replica, furious over Axel's betrayal. Though she fought with powerful thunder magic and her kunai, Sora defeated her in a decisive battle, making her the first Organization member to die at his hand.
Personality
Although Larxene is normally smiling and even winking at times in-game, she has a cruel personality and enjoys seeing others suffer hardships or anguish. She taunts Vexen incessantly after he is threatened with charges of treason and incompetence from Marluxia, and toys with Sora before fighting him the first time. After she discovers Axel's betrayal and sees that her and Marluxia's plans have fallen apart, her smile vanishes and she attacks Sora in a rage.
Fighting Style
Larxene fights largely using thunder magic, and is able to levitate off the ground and teleport. Her weapons are a set of kunai, used like they were claws as well as formidable throwing weapons. She uses lightning bolts and lightning tendrils capable of binding Sora in place.
Video
