WN/Zero

Zero was an artificial being created by Yuuki Kagurazaka who was accepted into the Eastern Empire's Mixed Corps. After Yuuki unleashed Armageddon, he reincarnated as a Seraphim and part of the Seven Executioners. Later, after being given the Ultimate Skill Azi Dahaka and successfully taking control of Ramiris' Dungeon, he fused with the skill and evolved into the "True Dragon" known as the Berserk Evil Dragon (狂邪竜)."

Personality
Unlike Vega, who was given an aggressive personality, he wasn't given personality but in exchange for that his Calculation is far superior than Vega, thus he could be considered as Yuuki's Ultimate Creation.

Background
He was Created by Yuuki via Unique Skill Creator

He was one of Yuuki's 300 elite subordinates

Ryuma Clash Arc
It's mentioned that he and the other 300 Yuuki's Elite Subordinate were gathered in Manor at Eastern Empire Capital under order from Yuuki in order to discuss about Coup d'état Plan after that he was Purged by Kondou, Damrada, Miraza, and the Royal Knights No.7 - 10.

Tenma Great War Arc
Arios, Zero, and Mai including 200,000 Angels were ordered by Velda to invade the Holy Empire Ruberios.

Later under Zero's instruction, Mai used her Unique Skill Traveler to Teleport Arios, Zero, and Mai back to Velda in order to evade the attack of Veldora's Ultimate Skill, Nyarlathotep.

During the attack on Tempest, Zero consumed the Labyrinth using Azi Dahaka. Because of the large energy from the Labyrinth, Zero lost control of his body to the Ultimate Skill and evolved into the Berserk Evil Dragon. He later was killed by Diablo, Benimaru, Zegion and Dino's combined attack and reduced down to his core which later combined with Velgaia and allowed them to take his place as a True Dragon.

Abilities
As one of Yuuki's Top Subordinate his abilities is far above Average Royal Knight.

Ultimate Skills

 * Master Shield, Star Shield
 * Azi Dahaka

Trivia

 * Although Arios is Leader of Seven Angel of Punishments, Zero is considered as the strongest member of Seven Angel of Punishments.
 * He could be considered as Vega's Little Brother.