Harem.

Runeas Gremory: The very first Gremory and a first-generation Devil created by Lucifer from Lilith's body. Mark summoned her accidentally when he tried to summon Sirzechs, but they match well together. She teaches Mark things she knows while he keeps her happy and entertained.

She and the members of Mark's harem are marked by his blood. This causes them to gain Draconic traits, but unlike Mark who has become a pure-blooded Dragon, they keep their original race and gain new powers accordingly.

Rias Gremory: She and Mark when they first met found the other interesting. Mark's Red Dragon instincts felt Rias' potential and the desire to steal her away. As for his human ones, he found her both an attractive girl and much like Runeas fun.

Calypso: Mark was informed of her existence by Hephestus when he wanted to recruit Titans to his side. He broke the curse placed on her by the Fates, but she still became infatuated with him.

Ingvild Leviathan: Mark met Ingilvid when he entered draconian hibernation. As they both slept for over a century. Her Sacred Gear Nereid Kyrie and Mark's Principle of Tyrrany allowed them to meet in their dreams. There they became closer.

Valina Lucifer: When Maulketh first met her, she had been turned into a boy by Azazel to hide her identity. When the effect wore off she turned back into a woman as the effect only lasts a week. After spending a considerable time around Maulketh her affection for him grew.

Tiamat: The Chaos Karma dragon challenged Maulketh to a battle alongside Crom Cruach. Crom Cruach became Maulketh's apprentice, while she submitted to Maulketh as a mate. Female dragons only take a mate once in their lives and only toward those stronger than them.

Astrid: She was once a beast like Volcano Born. A creature born from Lava, rock, and mana gaining life. She submitted to Maulketh when he devoured most of her race through his evolution. After evolving and becoming familiar her mind has developed from its former beast-like origin.

Celestine: A hybrid of a Water and Black Dragon given to Maulketh by Poseidon when she was still an egg. After feeding on his mana she had gained powerful fire abilities as well. After spending decades in a Time Formation she had matured along with her friend Astrid.

Akeno Himejima: Akeno and Maulketh started off rocky as she was afraid of him and he looked down on her. After her long period of training and the resurrection of her mother, she has worked past her trauma and become closer to him.

Trihexa: The first 'meeting', between Maulketh and Trihexa was actually a battle to the death. They both tore each other to shreds and even caused Maulketh to finally transcended into a Dragon God causing them to fall into a Dimensional Rift. The fight went on for more days, but they stopped fighting before a winner could be determined.

And through mutual respect, gave way to a bond forged through battle.

Ophis: Since Ophis met Maulketh, she had been raising him to become her mate once he became a Dragon God. She saw the potentiol of his Principle of Tyrrany, formed from the two Principles of Domination and Supremacy.

Now a Dragon God, she has fully accepted him as her mate just like Trihexa.

Kuroka: When she tried to see her sister Shirone, she ended up getting caught by Astrid, and given to Maulketh. As a Nekushou a rare and powerful race that drew Maulketh's Intrest. Now one of his harem members, she trained her sister to have the same privilege to be in his harem to join her.

Shirone: When Maulketh met Shirone, she was still a young traumatized girl. But through countless centuries of training in Time Distorting Dimensions she drew out the potentiol of her race and matured rapidly alongside her sister and fellow Peerage Members to the point where even Maulketh who called them unworthy centuries ago was forced to change his stance.

Now, she has earned his respect and her place among his harem.

Yunna Kimmi: Much like Shirone and Akeno who at first were not accepted by Maulketh due to their mental issues and their weakness as he called it. However, when guided by Rias, through many hard years of training mastered herself and through much of Rias' pushing, gained Maulketh's respect just like her friends had.

Though, she too joined his harem in the end under Akeno, Rias, Shirone, and Kuroka's pushing. Even Runeas encouraged her as the more women Maulketh has, the more grounded he will be.

Athena: Maulketh met her through Ares and once he conquered her Pantheon, killed her father Zeus, and freed her mother Metis, she became his Secretary and one of his War God generals. Now, she is one of his lovers and proud of who her future husband is.