Lea

Lea is one of the major characters of the Kingdom Hearts series. Lea has a desire to achieve his own ideal of immortality by having everyone remember his name. He was once Axel, a member of Organization XIII who served as its assassin, until the destruction of both Axel and his Heartless that allowed Lea to be reborn. Since then, Lea has become an ally of Sora and becomes a Keyblade wielder himself.

Personality
Lea is both childish and competitive, providing a perfect dichotomy with his close friend Isa. He is quite sarcastic and smug, but is friendly nonetheless. Despite his lightheartedness, Lea is dedicated to his wish to become immortalized. To him, living on through people's memories is the key to living forever, hence his use of the phrase, "Got it memorized?" on multiple occasions.

As a Nobody, Axel acts upon the memories of Lea; he is sarcastic, cocky, and laid-back but is known for being cold and merciless, and at worst apathetic for his comrades' lives. However, his cold personality changes when he strikes a friendship with Roxas, which slowly causes him to develop emotions that Nobodies would normally lack. As his friendship with Roxas and Xion grows, Axel demonstrates a kind, heartful side, acting like an older brother towards them and helping them out. This eventually causes him to become much more humane towards others and betrays the Organization to help Sora, who is Roxas' human form, and his friends, indicating how much his friendship with Roxas means to him.

As an adult, Lea has a mixture of both his and Axel's personalities due to retaining his memories as Axel. As a result, Lea becomes as cocky as his Nobody counterpart, to the point that he challenges Master Xehanort while defending Sora. However, Lea retains his younger self's traits, such as his competitiveness, especially when he learns how to wield a Keyblade.

Physical appearance
Lea is a slender young man with fair skin, blue-green eyes, and bright spiky, shoulder-length red hair with a widow's peak. As a teenager, his hair was similar to his current age, but shorter and with the spikes styled upward. He wore a sleeveless orange jacket with a white, sleeveless shirt underneath, and tan, baggy pants with red and white sneakers and black socks.

His Nobody, Axel, is nearly identical to his former self, however there are facial differences: unlike Lea, Axel's eyes are a strong emerald color, and he has purple reverse-teardrop shaped marking under each eye. Like other Organization members, Axel wears the basic black attire, however his black coat is slimmer than others and fits his slim build. Axel's Organization uniform remained as Lea's attire after he was reborn.

Powers and Abilities
Axel uses twin chakrams named "Eternal Flames", and has the ability to control fire. Using these in unison, Axel can perform a variety of complex fire attacks, such as summoning pillars of flame, surrounding his chakrams in flame to strike foes, and finishing off opponents in rapid attacks. These chakrams can also act as a detonator of sorts by lighting on fire from afar, as seen in Kingdom Hearts Re:Chain of Memories. Axel is a powerful member of the Organization, arguably even stronger, or at least a better fighter, than Saïx. This is seen when Saïx is defeated by Roxas, but Axel was able to defeat Xion at the Old Mansion, who at the time absorbed much of Roxas's power. As a high-ranking Nobody, Axel also has control over the Assassin Nobodies.

Upon reaching adulthood following his Nobody and Heartless' destruction, Lea inherits the chakrams, and after Sora and Riku's Mark of Mastery exam comes to an end, he becomes a Keyblade wielder by revealing his ability to wield a flame-themed Keyblade due to receiving a magically compressed training session from Yen Sid, Merlin and the three fairies.

Kingdom Hearts: Chain of Memories
While Sora and Riku wandered around in Castle Oblivion, Axel was deployed by Xemnas, his superior, to eliminate members in the castle planning to stage a coup of the Organization while using Naminé to alter Sora's memories. At the same time, he had a private plan with Saïx to eliminate the members of the Organization that would stand in the latter's way of advancing through the ranks. At first, Axel joins the conspiracy to act as a double agent, cementing his trust with Marluxia by eliminating Vexen. Using this to his advantage, Axel allows Naminé to escape and contact Sora. He later confronts Marluxia to finally destroy him, only for the rebel member to escape from Axel after tricking Sora (who had just arrived on the scene) into attacking Axel. After his battle with Sora, Axel had the Riku Replica absorb Zexion to fight the real Riku, leaving him as the only surviving member of the Organization in the castle, before returning to The World That Never Was.

Kingdom Hearts II
Axel appears in the Digital Twilight Town Roxas was trapped in to bring Roxas back to the Organization; however, due to the programming of the world and DiZ's interferences, Roxas fails to recognize him. Although these efforts seem in vain, Roxas learns later on that the two had been best friends from Naminé. When Roxas finally recovers his memories, Axel meets him once again but tries to attack him due to feeling hurt from his previous encounter with Roxas. Axel loses the fight and disappears, choosing not to carry out his mission. During Sora's adventures in the different worlds, Axel kidnaps Kairi to draw Sora out in order to get Roxas back. Although Kairi escapes from him, she is captured by Saïx this time. Soon, Axel decides to actively help Sora and his friends out on their way to The World That Never Was when the group is caught in an ambush by Nobodies. When their numbers prove too great, Axel sacrifices himself to destroy them in order to save Sora, as he was Roxas' original self. In his last few moments, Axel sincerely apologizes to Sora for getting Kairi involved and urges Sora to rescue Kairi. With his last bit of strength, Axel opens the passageway to the World That Never Was for the group before disappearing into darkness.

Kingdom Hearts 358/2 Days
Taking place before and during Chain of Memories, Axel is one of the main characters of the game, his role being the instructor for Roxas during his induction into the Organization. Initially, Axel was unsure how to treat Roxas, but over time the Nobodies begin to bond. As their friendship grew strong, Axel began to demonstrate emotions due to his time with Roxas. Soon, Axel is sent to Castle Oblivion to deal with the traitorous Marluxia, the content of these events being detailed in Chain of Memories.

When Axel returns, Roxas had managed to forge a friendship with Xion, causing Axel to become jealous. However, as the three begin to spend time together as a trio, Axel learns to enjoy Xion's company. Unfortunately, Axel finds himself before Saïx, where the two come into conflict due to the friendship they had in their past lives as Lea and Isa. Eventually, when both Roxas and Xion leave the Organization, Axel is forced to bring Xion to Xemnas, much to Axel's guilt. After learning of the aftermath of Roxas and Xion's fight with Xion being destroyed, Axel becomes depressed and is left contemplating over the times he spent with them.

Kingdom Hearts Birth by Sleep
Lea makes his first chronological appearance in the series in the game's prequel set 10 years before Kingdom Hearts. In the Radiant Garden, Lea walks with Isa by Ventus. The two introduce themselves to him, and quickly bond after a short fight. Lea then states that they'll meet again someday, because he and Ventus are now friends.

Following this event at an unknown point, Lea's heart would be consumed by darkness, turning him into a Heartless but allowing him to continue on as Axel. Sometime later, Axel joins Organization XIII as Number VIII. It is known that he joined alongside Isa, now known as Saïx, and the two had a secret, unknown plan.

Kingdom Hearts 3D: Dream Drop Distance
Following the destruction of his Heartless and Axel's suicide, Lea is reborn as an adult and awakens in Ansem the Wise's computer room along with Ienzo, Aeleus, Dilan, and Even. Realizing that Braig and Isa are missing, Lea decides to search the worlds for them and leaves Ansem's study. While traveling, Lea arrives at Disney Castle in time to defend King Mickey via his chakrams from a magic blast from Maleficent and allow Queen Minnie to escape safely from Pete, forcing the two villains to retreat. He then goes with the group to Yen Sid's tower, where he requests to become a Keyblade wielder to help Sora/Roxas. Yen Sid allows him, and Lea begins his training. When Sora is captured by Master Xehanort, Lea joins in the effort to save him. Much to his shock, Lea finds Isa/Saïx on the side of Xehanort. The group is forced to retreat after saving Sora, however, before Lea can find out the truth behind this turn. After Riku saves Sora's heart from darkness, Lea reveals his ability to materialize a Keyblade of his own, much to everyone's shock, promising that he will help them in the coming battle against Master Xehanort.

Trivia

 * To call Axel's weapon a Chakram is a fallacy; in real life, chakrams are small razor-edged throwing disks. Axel's Chakrams bear more of a resemblance to Chinese wind-and-fire wheels, wheel-shaped weapons that are used strictly as melee weapons.