12,000 years before the Celestial Genesis Era and the Holy Genesis Era, Apollonius created the legendary Mechanical Angel Aquarion, or just "Aquarion", in order to fight the Shadow Angels after he betrayed them when he fell in love with the human princess, Celiane.
When creating Aquarion, Apollonius divided Aquarion into three Vectors because the bond between Apollonius and Celiane was too strong. Due to their intense bond, they could destroy the world together, even 12,000 years later. So a third Vector was needed to balance the other two so that Apollonius and Celiane would not focus only what the two of them see.
In order to merge into any form of Aquarion, the Elements must combine their mind, body, and soul into one unanimous form. Their stability heavily rely on the pilot's state of mind and body, and if the pilot is unwell, Aquarion's merge will dissolve back into the three vectors.
- Back when Apollonius, Celane, and Scorpius were the three main pilots of Vector Mars, Vector Sol, and Vector Luna, Aquarion was always in it's Legendary form due to having a Shadow Angel (Apollonius) in the cockpit of one of the vectors.
- The Legendary Aquarion is Aquarion's true form.
- Aquarion holds part of Apollonius' soul, giving it some apparent form of consciousness and will.