Zeoticus Gremory

Zeoticus Gremory is the current head of the Gremory Clan. He is the father of Rias Gremory and Sirzechs Lucifer and grandfather of Millicas Gremory.

Appearance
A middle-aged looking man with long crimson red hair that is tied as a loose ponytail with a black hairband. He has bright blue eyes just like his two children, Sirzechs and Rias Gremory. He also has a short and red beard or stubble.

Personality
Coming from the Gremory Clan that has extra-ordinary affection, Zeoticus has demonstrated a extremely kind disposition.

History
Little is known of Zeoticus's past, except that he married Venelana Bael and eventually fathered two children: Sirzechs and Rias. When Sirzechs became the Satan, "Lucifer" and lost his right to become the Head of the Gremory Clan, Zeoticus made an arrangement with the Phenex Clan for his daughter to marry Riser Phenex at some point before the series.

The Red Dragon Emperor's Awakening
He first appears in Volume 2 at Rias' engagement party and was shocked at the sudden appearance of Issei Hyoudou that is set up by his son. After Issei beats Riser Phenex, he has a conversation with Riser's father, Lord Phenex, apologizing to him and Riser for the results of the match as well as the broken engagement (although Lord Phenex didn't really mind).

Birth of the Breast Dragon Emperor
Zeoticus reappears in Volume 4, where he and Sirzechs went to the Kuoh Academy for Rias' class observation day. He appears again in Volume 5 when Rias and her peerage return to the Underworld.

The Heroic Oppai Dragon
In Volume 12, Azazel recalled a conversation that he had with Zeoticus, in which he told Azazel that he sometimes questioned himself as to whether Sirzechs could actually be called a Devil. When asked by Azazel as to what he meant, Zeoticus states the Sirzechs is a mutation of a Devil and that Sirzechs, Ajuka, and another unnamed Devil as the only Super Devils of the Underworld. He also added that perhaps it was Sirzechs and Ajuka's destiny to become Satans because there is no other post for the two of them to have.

The Legend of Oppai Dragon and his Lively Companions
In Volume 21, After Issei leaves the hospital with his friends and heads to the battlefield, Zeoticus goes to comfort Issei's parents who are worried for their son, he assures them that they will all return back alive.

Powers & Abilities
Demonic Powers: As the head of the Gremory, Zeoticus has strong Demonic Power.

Flight: Being a Devil, Zeoticus can fly with his wings.

Trivia

 * Zeoticus's only known peerage member is his Bishop, Heinrich Cornelius Agrippa.
 * Zeoticus is likely hundreds of years old, as his Bishop, Heinrich Cornelius Agrippa, lived and died during the early 1500's.
 * He acts as the mascot character "Gomorin" to represent the House of Gremory.
 * In both the light novel and manga, he and Lord Phenex discuss about the Welsh Dragon and the impending arrival of the Vanishing Dragon, while in the anime this conversation is held between Sirzechs Lucifer and Grayfia Lucifuge.
 * In Volume 14, Rias mentions that Zeoticus has a pact with a Magician.
 * Venelana reveals that Zeoticus has a harem which she manages.
 * Zeoticus is a good cook.
 * Zeoticus' name is taken from the characters in the Gundam franchise, Zeon Daikun + Marticus Rex.