Marluxia

Marluxia, the Graceful Assassin (優雅なる凶刃, Yūga-naru Kyōjin?, lit. Graceful Assassin's Blade), is Rank XI within Organization XIII, the lord of Castle Oblivion and the main antagonist of Sora's story in Kingdom Hearts: Chain of Memories. He controls flowers, and uses his control to command beams of destructive energy from flower-themed minions, bombard the opponent with flurries of petals, and to attack opponents with his massive scythe.

Originally discovered by senior Organization members Xigbar and Xaldin, Marluxia is the mastermind of an internal rebellion in the Organization against Xemnas. Marluxia makes an appearance in Kingdom Hearts 358/2 Days and is a playable character in Mission Mode.

Kingdom Hearts 358/2 Days
Like other members of the Organization, Marluxia aids Roxas in at least one mission. He is polite to Roxas in their mission. On the first, he teaches Roxas how to collect Hearts and explains to him about Heartless. He explains the differences between Pureblood Heartless and Emblem Heartless and to only attack Emblem Heartless to release Hearts. He also explains to Roxas that after he releases hearts, they form Kingdom Hearts, and that Roxas is the first one to accomplish this. This also shows his greed over the Keyblade. On the next, he helps Roxas fight some Dire Plants by The Old Mansion and Zip Slasher in Twilight Town. Later, he is assigned to Castle Oblivion with the other members.

Before Axel leaves for Castle Oblivion, it is revealed that Saïx knew about Marluxia's plans to overthrow the Organization. That is why he sent them and the other "suspicious" members to Castle Oblivion, along with Axel who was given orders to eliminate any of the members that planned to overthrow the Organization.

Kingdom Hearts: Chain of Memories
Marluxia, working with Larxene and Axel, plots to overthrow the Organization. They formulate a plan to use a young girl named Naminé, who has a mysterious power over memory, to deceive Sora into thinking he had sworn to protect her, and then have her use Sora to help them defeat the senior Organization members. This plot stems from a rivalry between some of the younger Organization members and the original six core members. Vexen, Larxene, and Axel all do their part to feed Sora with information and lure him further into the castle. Each of them fight him on their own, although none of them use their full strength and throw the fights. They also make use of Vexen's Riku Replica to compete with Sora for Naminé's loyalty.

Marluxia and Larxene eventually learn that Vexen has been reporting back to Lexaeus and Zexion regarding their revolt. After Vexen loses control of the Riku Replica, Marluxia pronounces his project a failure. After Vexen arrogantly protests that Marluxia has no business speaking to him in such a manner, Marluxia claims that his mastery over Castle Oblivion allows him the authority to do so. Marluxia threatens to tell "the Superior" of Vexen's failure, but Vexen pleads with him not to do so. Marluxia agrees not to if Vexen eliminates Sora. Although confused by the order, Vexen agrees, and heads Sora off in the Twilight Town world. He fights Sora for the second time, but is again defeated. Before he can reveal Marluxia's plans to use Sora, however, Axel destroys him on Marluxia's orders, making Vexen the first Organization member to be eliminated.

Axel's assassination of Vexen allows him to gain the full trust of Marluxia and Larxene. As Sora nears the top floors of the castle, Axel is left alone with Naminé to keep watch over her. Instead of keeping an eye on her, Axel allows her to escape, freeing her from Marluxia's control and ending her continued restructuring of Sora's memories, effectively ruining the plot to manipulate Sora into fighting the Organization. This prompts Larxene to attack Sora shortly after he defeats the Riku Replica for the final time, but she is killed in the struggle, leaving only Marluxia to carry out the plot.

Axel then confronts Marluxia, who is disgusted with Axel for betraying him, to which Axel replies that Marluxia is in fact a traitor to the Organization, and that Larxene paid the price for her own disloyalty. He then threatens to kill Marluxia, but Marluxia seems unfazed by this, stating simply "You can try.". The two then engage in battle, with Marluxia displaying an eerie speed. While they both attack one another powerfully, neither takes any actual damage and appear to be equally matched.

Marluxia makes Naminé appear in front of him, apparently as a shield to prevent Axel from attacking him further, but Axel laughs it off, saying he's willing to go through Naminé to get to Marluxia. Marluxia, however, tells Sora (who had just appeared in the room, much to Axel's surprise) that Axel was willing to hurt her and vanishes with a laugh, leaving Sora and Axel alone. Axel sneers at Sora for having become Marluxia's puppet after all, but Sora resolves to eliminate Marluxia right after he finishes Axel. The two fight, and Sora comes out the victor, but Axel escapes death and vanishes.

Sora pursues Marluxia into his inner chambers. Marluxia orders Naminé to completely erase Sora's memory and destroy his heart, hoping to rebuild him into something more to his liking afterward. However, Naminé, remembering Sora's kindness towards her, flat-out refuses the order, even when faced with death. Marluxia is perplexed when Sora orders Naminé to do so for her own safety, and even more so when the revived Riku Replica attacks. Confused and irritated that Sora and the replica would accept their memories of Naminé with the full knowledge that they are lies, Marluxia attacks them. Sora destroys Marluxia, but finds that the real Marluxia had been hiding in a back room and that his opponent had only been a clone. Sora advances into the final room to confront Marluxia, who has combined with his Specter (スペクター, Supekutā?) in both Grim Reaper and Angel of Death-like forms. Sora defeats him again in the storyline's final battle, with Marluxia trying to reach Sora but then fading in a flurry of flower petals, making him the fourth Organization member to fall.

The manga version of these battles differs from the version of the Chain of Memories games. In it, Marluxia does not use alternate forms and is easily killed by Sora in the first battle. He is also surrounded by flowers or flower petals a good deal of the time. And he is sometimes even seen holding a rose.

Kingdom Hearts II
While Marluxia doesn't directly appear in Kingdom Hearts II, he is seen guiding Sora towards Castle Oblivion in the last of Roxas's dreams. Sora also recieves his journal data after accessing Ansem's computer. Sora also battles Marluxia's Absent Silhouette and Data Replica once he finds them.