Lea

Lea is the original persona of Axel, and a close friend of Isa, Saïx's original persona. He appears in Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix, as a teenager, alongside Isa, and then in Kingdom Hearts 3D: Dream Drop Distance, more grown up, almost identical to Axel.

Kingdom Hearts Birth by Sleep
''A likable, upbeat boy who tends to jump into things without consulting anybody else---sometimes with disastrous results. He seems to be hung up on other people remembering him, and taught Ventus the importance of making friends.''

He and his own best friend, Isa, have bigger plans.

Kingdom Hearts Birth by Sleep
While Ventus is in the Radiant Garden, Lea walks by, picking up the Wooden Keyblade from the ground. He asks Ventus if it's his. When Ventus responds that it is, Lea says it's cute how he still plays with wooden swords, despite his age and takes out his Frisbees. The two introduce themselves, and then Lea calls for a one-on-one fight, finally prompting a smile.

After the battle, Lea calls Isa out for not trying to make up excuses for his loss causing Ventus and Isa to laugh. He then states that they'll meet again someday, because he and Ventus are now friends. After that, Lea and Isa walk off and look up at the castle, apparently 'ready.'

Sometime after Terra-Xehanort is defeated, Lea and Isa's plan is revealed, as both were seen being thrown out of the castle by Dilan with Aeleus looking on nearby. In the next scene, Lea buys sea-salt ice cream from Scrooge McDuck and gives one to Isa as they stare up into the sky.

Lea's and Ventus's newfound friendship makes many possible references to the subsequent friendship between Axel and Roxas.

Between Kingdom Hearts Birth by Sleep and Kingdom Hearts 358/2 Days
At an unknown point in time, Lea's heart was consumed by darkness, turning him into a Heartless. However, his strong heart and will gave him the ability to continue on as a Nobody: Axel. Some time later, Organization XIII found his Nobody, who received the name Axel and was inducted into their ranks as Number VIII. It is known that he joined alongside Isa, and the two had a secret, unknown plan.

Kingdom Hearts 3D: Dream Drop Distance
After both his Heartless and his Nobody having been defeated, Lea comes to in Ansem's computer room in Radiant Garden, and notices his lack of eye markings before realizing that he is a complete being again.

Making his debut appearance in the Jump Festa trailer for Kingdom Hearts 3D: Dream Drop Distance, where he is shown protecting Mickey from Maleficent's attack with his Chakrams. He proceeds to introduce himself, saying "My name is... Lea" along with his trademark "Got it Memorized?". He is also shown in an earlier scene talking with Aeleus and Ienzo, stating how he dislikes being tasked to look for the other revived members of Organization XIII.

A new trailer, other than showing him being restored to his normal self, features Lea discussing something with Yen Sid about a quest that he wants to partake regardless of the latter warning him of the dangers to befall him.

Near the end of the story, Lea shows up saving Sora from Master Xehanort who was about to split his heart and make him touch the darkness. He has a short "battle" with his childhood friend Isa. The ending shows him summoning his Keyblade, surprising Sora, Riku, Donald, Yen Sid, Goofy, and Mickey. He then stays at Yen Sid's castle to train with the Keyblade.

Appearance
In Birth by Sleep, Lea looks about the same age as Ventus, with short spiked hair with the spikes styled upward. Lea has a slight widow's peak though more noticeable. Lea's eyes are also more of a turqoise 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 lacks Axel's purple, upside-down teardrop facial marks in the actual game, but curiously they are present in his official artwork.

He also wears a yellow and brown keffiyeh 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.

Lea carries around two red Frisbees with black edges, each adorned with a Bomb design, which later influence his choice of weapons when he grows up: chakrams.

In the upcoming Kingdom Hearts 3D: Dream Drop Distance, other than missing the teardrop facial marks, Lea is identical to his Nobody, Axel, donning a Black Coat and wielding the Eternal Flames, and later, an unknown Keyblade.

Personality
Lea is both childish and competitive, willing to disrupt Isa's schedule for his 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 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.

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.

Notes and references
Lea Lea