From Aozora Wiki
Dullian (ダルリアン, Dulian) is a character from the Aozora's Adventure series.
Dullian is an angel that was "born" from the result of a particular type of magic that Jullian accidentally cast on himself within one of the rooms of a celestial palace in the skies. Due to the nature of the magic, the entity that spawned mimicked Jullian's physical shape, powers, and clothing style, but adapted a more corrupt version of Jullian's personality, sporting darker indigo and purple clothing and jet black wings. After his sudden creation, Dullian stormed out of the palace at fast speeds, giving Jullian no time to see the copy in full.
Dullian typically enters battles by lurking high in the sky and diving down at a high speed towards Jullian when he least expects it, knocking him out and launching him into the distance, taking his place in the process. Dullian usually does this if he considers the opponent or scenario Jullian is about to face too strong to fight "such a weak little thing", prompting his appearance to give a bigger challenge. Due to this, Jullian is highly paranoid of Dullian's presence and when he'll strike next. If Jullian attempts to return to the scene, Dullian will either flee on the spot or rarely- stay behind to challenge him.
Powers and Abilities
Unlike his "good" counterpart, Dullian uses more advanced gear, giving him superior strength and agility. The fires his ignites his weapons with are colored a dark purple instead of the red flames used by Jullian.