Lea

Lea is the human form of Axel, and a former close friend of Isa, Saïx's human form. He appears in Kingdom Hearts Birth by Sleep as a teenager, alongside Isa, and he returns as an adult in Kingdom Hearts 3D: Dream Drop Distance, in which he chooses to become a Keyblade wielder.

Kingdom Hearts Birth by Sleep
By the time Terra and Aqua had left Radiant Garden, Lea had conspired with his best friend, Isa, to break into Ansem the Wise's castle (for unknown reasons). When walking past the town square, Lea notices Ventus drop his Wooden Keyblade and picks it up, offering to give it back to him. Though Isa tells him they need to hurry, Lea tells him to lighten up since "it will only take a sec". He calls Ventus a kid for "playing" with a wooden "toy" and proudly takes out his frisbees, saying they're real weapons. Lea introduces himself and Isa, asking for Ventus's name. Once the introductions are done, Lea asks Ventus to fight with him, much to his confusion. Ventus agrees with a smile while Isa only looks on with a laugh, knowing it's just like Lea to do this.

Because Ventus was a trained Keyblade wielder, and not some average kid, Lea didn't stand a chance in a practice fight, ending up heavily exhausted while Ventus barely broke a sweat. Catching his breath, Lea tells Ventus that he was willing to call their fight a draw if he was, earning confusion in return. Isa then says the only thing Lea drew was "an L on your head for 'loser', 'lame', 'laughable'". Annoyed, he tells Isa that he's supposed to make him feel better by making up excuses like "you shouldn't pull your punches" or "you're having an off day". The three of them laugh at the argument. Isa then reminds Lea that they have to go, taking off before him. He then tells Ventus that they'll meet again someday, because they are now friends. Isa wonders why he keeps "picking up stray puppies", and Lea tells him that he wants to live forever in the memories of everyone he meets. Lea then declares himself immortal after Isa jokes about trying to forget him all the time. After that, Lea and Isa walk off and look up at the castle, apparently 'ready.'

Sometime after Terra-Xehanort is defeated, Lea and Isa are seen being thrown out of the castle by Dilan with Aeleus looking on nearby; Lea struggled in vain to get free while Isa knew there was no escaping Dilan's grip. Lea later buys sea-salt ice cream from Scrooge McDuck and gives one to Isa as they stare up into the sky.

Between Kingdom Hearts Birth by Sleep and Kingdom Hearts 358/2 Days
At some point in time, Lea and Isa's hearts were consumed by darkness and transformed into Heartless; this event happened in Ansem the Wise's computer room, along with the apprentices. However, their strong hearts and wills allowed their vessels to continue on as Nobodies. Organization XIII eventually found the pair and named them "Axel" and "Saïx", then inducted them in as Numbers VII and VIII. However, the two had joined the Organization in order to carry out a secret plan to take it over.

At some point, Lea's Heartless was destroyed by Sora, setting the stage for Lea to reform once Axel is destroyed.

Kingdom Hearts 3D: Dream Drop Distance
After Axel sacrifices himself to give Sora safe passage to The World That Never Was, Lea has a dream of Roxas reminding Axel of the promise he made to him and Xion to always be there to bring them back, and awakens in Radiant Garden, with his memories of his time as Axel intact. Discovering that four of the founding members of Organization XIII, Aeleus, Even, Dilan and Ienzo, have been reborn as well, Lea decides to look around for the missing Braig and Isa. After talking with Aeleus, he finds out there is no one else in the Castle. Deciding to check the castle grounds, Lea is told by Aeleus not to bother. Ienzo explains to Lea if Braig and Isa were reborn, they would have been with them. This makes Lea wonder if Braig and Isa could have been "blasted off to another world", which Ienzo explains is possible if the world they came from no longer exists when they are reborn; they'd reappear in Traverse Town or a similar place if that was the case. Lea finds Ansem the Wise's notes about the Door to Darkness, and leaves to find the still missing Braig and Isa, complaining that he always gets stuck with the icky jobs.

Lea's travels eventually bring him to Disney Castle, where Maleficent and Pete are holding Queen Minnie hostage against Mickey, Donald, and Goofy inside the castle library to acquire the Datascape for their own nefarious schemes. From within a Corridor of Darkness, Lea discreetly uses his chakrams to block Maleficent's attack against Mickey and surprise Pete long enough for Minnie to escape from his clutches, and once Maleficent and Pete are gone, Lea introduces himself to Mickey and his friends. Lea later joins Mickey, Donald, and Goofy inside the Mysterious Tower and requests to become a Keyblade wielder, shocking everyone present. Yen Sid warns Lea that the road he has chosen will not be easy, but Lea decides to "jump right in" anyway. He is then helped with his training by Merlin, along with Flora, Fauna and Merryweather, by using their magic to compress the time his training would take.

Learning of the danger everyone else is in, Lea arrives just in time in The World That Never Was, saving Sora from becoming Master Xehanort's final vessel in the new Organization XIII. Xigbar calls him "Axel", which Lea corrects him on, explaining that he'll always be there to bring back his friends. Lea then jokes to Master Xehanort that he plotted his "script" so well, but forgot to "write the sequel". When Xigbar questions the "old coot" on what to do because they are out of time, Lea is attacked by a hooded member, who clashes a claymore against his chakram. The resulting shockwave knocks off the unknown member's hood to reveal Saïx. Lea is shocked to see his former friend aiding Master Xehanort, even becoming one of his clones. Hudling with Mickey and Riku, Lea finally relents about others calling him "Axel" after Riku refers to him as such and says they should escape. Then he sees that they're in trouble when Ansem's Guardian tries to squeeze Riku and Mickey to the point of death. Luckily, Donald and Goofy arrive, taking out the Heartless. With the extra allies, Master Xehanort is forced to retreat with his new Organization until they get their thirteenth heart of darkness, with Lea sharing a final look with Saïx.

Back in the Mysterious Tower, Riku decides to go back into Sora's dream to awaken him. Lea tells Riku if the darkness gets him again, then he will help out since ""Dark Rescue" is his middle name". After Riku succeeds in awakening Sora, Lea then joins him and the others in a tea party while Riku is recovering. Once Riku wakes up and Yen Sid declares him a Keyblade Master, Lea tells Riku that he'll catch up to him in no time. Sora then asks if he also wants to become a Keyblade Master, to which Lea answers yes. Lea then explains that when he showed up to save them, he planned on arriving, wielding his new Keyblade, but he hasn't been able to summon it yet. Thinking it's in the way he moves his wrist, Lea tries one more time and successfully summons his Keyblade, shocking everyone present. He then, almost immediately, returns to Radiant Garden.

Appearance
During his youth in Radiant Garden, Lea looks about the same age as Ventus. His hair resembles his Nobody's, but shorter and with the spikes styled upward. Lea has a slight, a trait he also shares with Axel, though Lea's is more noticeable. Lea's eyes are also more of a blue/green color than Axel's striking green. He wears a sleeveless orange jacket with a white, sleeveless shirt underneath, and tan, baggy pants with red and white sneakers and black socks. The pockets of his jacket are a much darker shade of orange than the rest of it. He also wears a yellow and brown around his neck. The pattern of this keffiyeh changes abruptly near Lea's neck, from stripes to a very organized checkerboard pattern. Similar to Braig's scarf, the tip of Lea's keffiyeh is frayed slightly. He bears a curious resemblance to Hayner.

After being revived following Axel's demise, Lea wears the black coat he wore during his time as Axel and appears identical to his former Nobody, only lacking the tear-shaped markings below his eyes.

Personality
Lea is both childish and competitive, willing to disrupt Isa's schedule for his impromtu fight with Ventus. This is also evident during the ending credits when he is seen trying to escape from Dilan's grasp by flailing around his limbs, unlike Isa, who realized they couldn't escape and barely moved. He is also somewhat smug and sarcastic just as Axel was.

He wishes for everyone he ever meets to remember him, so he can live on forever through people's memories. Like his Nobody, he uses the phrase "Got it memorized?" on multiple occasions.

As an adult, retaining his memories as Axel, Lea becomes as cocky as his Nobody counterpart, to the point that he actually challenges Master Xehanort while defending Sora, even though he would be using his chakrams against Master Xehanort's Keyblade. Even so, he retains his competitive streak, demonstrated when he states that he intends to compete with Riku in the art of the Keyblade.

Abilities
As a teenager, Lea is not physically shown fighting, though he has an offscreen spar with Ventus and loses. His weapons during that time consist of two red frisbees with black edges, each adorned with a Bomb design, which later influence his choice of weapons in the Organization: chakrams.

Upon reaching adulthood following his Nobody and Heartless's destruction, Lea wields the fire-controlling Chakrams once used by Axel, and after Sora and Riku's Mark of Mastery exam comes to an end, he reveals his ability to wield a Keyblade that bears features from the Bond of Flame and Frolic Flame Keyblades, having received a magically compressed training session from Yen Sid, Merlin and the three fairies.

Trivia

 * In an issue of Famitsu PSP+PS3, Lea's name is misspelled "Lia". It was also once misspelled on the Kingdom Hearts Birth by Sleep official website, though it was later corrected.
 * Although it was a joke, Lea's statement that he should have been friends with Ventus rather than with Isa foreshadows future events. In the future, his Nobody would choose to become friends with Roxas rather than stay friends with Saïx, Isa's Nobody.
 * A running gag during Kingdom Hearts 3D: Dream Drop Distance is whenever Lea meets someone from his past, they call him "Axel" and he has to correct them. At the end of the game, when Riku calls him "Axel" again, Lea finally relents.