The Grand Unified Theory
Who are the Noah?
The Noah are the disciples of Adam, whose previous world was destroyed. They are “immortal“ in the sense that even in death, their soul does not lose its memories upon returning to the Helix; this is known as Noah Memory. This is why they have memories of the previous world and can be reborn in “hosts”. They are not directly related to the Earl and pretend to be his family (this part I’m not 100% sure of, since the Earl may be Adam). They manipulate the Earl to make sure he does not once again turn into the world ending Pillar.
Who is the Earl?
The Earl is actually the Heart and its accommodator (who may be Adam). The Heart and its accommodator do not necessarily share the same goal. In the past the world was destroyed by the Pillar (the Earl aka The Heart) for reasons unknown. The current reincarnated Earl became aware of his contradictory nature; torn between his duty to both the Heart and Noah, he split himself into two halves, each embodying one mission. Nea represents the Heart, hence why he can manifest in Allen and why Allen’s Innocence and the Innocence of those around him exhibit miraculous properties. Once Nea became aware of the history of the Earl, he murdered the Noah for their manipulation. Mana represents the Noah half, in order to protect the Noah, he developed a personality that he believes to be the original “Earl”, and devoured Nea in order to seal him once more within a single entity. The Heart feeds on Helix energy, and current Earl still commands the Heart’s power to consume souls, the most concentrated form of Helix energy.
Why create Akuma?
Akuma are made out of the wishes of the Noah side of the Earl. Since the Heart has the power to consume souls, normal humans have no chance against it. When an Akuma is created, a soul is forcefully returned to the physical plane from the Helix through a massive burst of Helix energy (the desperation of a loved one). This begins a long process of defying the natural order. As the soul no longer belongs in the material world, there is now an empty place in the Helix that needs to be filled. By defying fate and killing humans before their due time, the Akuma uses their souls to fill the gap left behind. This results in the Helix no longer having a space for their soul to return to. The more an Akuma kills the less space remains in the Helix, and the more their soul deteriorates. The goal is to create an Akuma without a soul, a weapon the Heart will have no power over. In a Level 4 Akuma the soul is nearly destroyed. Innocence and unknowing exorcists kill Akuma to prevent the birth of this ultimate weapon.