Ienzo

Ienzo was one of the six apprentices of Ansem the Wise who made his debut in Kingdom Hearts Birth by Sleep. Ienzo is the original persona of Zexion; his existence continued on as Zexion after his fellow apprentice, Xehanort, led him to his gradual descent into darkness. Ienzo is also mentioned in the Secret Ansem Reports found in Kingdom Hearts II.

Kingdom Hearts Birth by Sleep
Ienzo appears in Kingdom Hearts Birth by Sleep as a minor character with no speaking lines. His parents passed away for an unknown reason. Disobeying the orders of his master to stay inside the castle, Ienzo was ultimately surrounded and attacked by Unversed until Ventus came to his rescue. Shortly after the battle, his escort Even arrived and gave Ventus both his and Ienzo's thanks, explained Ienzo's past and that he had been assigned to take care of him since the death of his parents, gave Ventus the directions to the Outer Gardens where he would find Terra, and returned to the castle with Ienzo.

Blank Points
As Braig is interrogating Xehanort on his state of mind, Ienzo and Ansem walk past, eating sea-salt ice cream. The pair stop and turn to see Braig and Xehanort walking away, still deep in conversation.

Between Kingdom Hearts Birth by Sleep and Kingdom Hearts 358/2 Days
Ienzo was still one of six apprentices of Ansem the Wise, the ruler and scientist of Radiant Garden, alongside Braig, Dilan, Even, Aeleus, and Xehanort. Worried the Darkness in people's hearts would eventually consume his world, Ansem began performing tests on Xehanort's heart. Eventually, at Ienzo's persuasive influence, he created a laboratory in his castle's basement for such experimentation. However, Ienzo and the other apprentices had their own intentions for the laboratory, and began conducting inhumane experiments on the human heart and the darkness within it. Such experimentation led to the creation of the Heartless. Ansem quickly discovered their secret experiments, and immediately ordered them to stop. One day, after being advised to review their research data by King Mickey, Ansem found that the effects of their experiments had become irreversible.

Eventually, Ienzo and the other five apprentices dabbled too deeply into darkness through their continued experiments. Ienzo, along with the others, was consumed by the darkness, producing a Heartless. However, the apprentices all had strong wills, and so Ienzo became a Nobody ultimately named Zexion. The six Nobodies formed Organization XIII, and banished Ansem the Wise to the Realm of Darkness.

Kingdom Hearts 3D: Dream Drop Distance
Ienzo is restored to human form, now as an adult, following the destruction of his Heartless and Zexion. He awakens in Hollow Bastion along with Dilan, Aeleus, Even, and Lea, and they soon discover that Braig and Isa are missing. Ienzo explains to Lea about how a person is meant to return to human form in the same world he or she lost his or her heart, which prompts Lea to go out to search for Braig and Isa. Interestingly, Ienzo does not appear bitter towards Lea for his betrayal during their time in the Organization.

Ienzo also appears in Xehanort's flashback, where he is seen lying on the floor as a child with Even, unconscious and with specks of darkness coming from his body.

Appearance
Like his fellow apprentice Even, Ienzo has a scientist-like appearance, wearing the same white coat that Even wears over a black, V-neck top with a white collar. Oddly, Ienzo appears to be much younger than his Nobody, Zexion, perhaps even younger than Ventus, making him the youngest of the apprentices. Otherwise, he completely resembles his Nobody, Zexion, with a few minor changes such as shorter, lighter hair. His eyes also appear to be a lighter shade of blue. Likely due to his size, Ienzo folds the sleeves of his lab coat back, and even then his hands are partially covered. He also wears blue pants and navy blue shoes, as opposed to the other apprentice's black boots.

As an adult, Ienzo looks identical to Zexion. He wears a white lab coat with a purple ascot similar to the one worn by Xehanort during his time as Ansem's apprentice.

Personality
As a child, Ienzo was quiet, yet observant and curious. It appears that he spent most of his time with Even, sharing with him his love for knowledge. He also seemed to have a good relationship with Ansem, as they are seen sharing sea salt ice cream together while Ienzo holds his hand. It was also due to Ienzo's persuasion that Ansem built his laboratory, implying that he valued Ienzo's opinions despite his young age.

As an adult, Ienzo appears much more talkative and scholarly, actually jabbering while explaing to Lea how Nobodies are reborn. He also appears to be rather cheerful and doesn't seem to hold any grudges against Lea for betraying him and convincing the Riku Replica to absorb his life force as a Nobody.