Fafnir's current contract partner. Asia made a contract with Fafnir when Azazel's contract with Fafnir was nullified. To establish the contract, Asia has to pay the price of her panties as an offering. Despite his pervertedness, Fafnir cares deeply for Asia and is extremely protective of her, so much so that he went berserk when Rizevim Livan Lucifer attacked her.
Issei first met Fafnir when he needed the help of another Dragon King's help in recovering Ddraig's mentality which much to Issei's dismay, Fafnir was a perverted Dragon that takes Asia's panties as part of their contract in exchange of Fafnir's help each time he's summoned.
Fafnir's previous contract partner. He helped Azazel in his Sacred Gear research, allowing himself to be sealed in Azazel's Artificial Sacred Gear. Their contract was nullified when Azazel stepped down from his position as Governor of the Fallen Angels.
Ophis was the mediator between Asia and Fafnir when they were forming a contract. Later on in Volume 15, he seems to be on friendly terms with both Ophis and Rassei, as shown when he let her sit on his head while watching Asia, who was swimming in the pool in the Hyoudou Residence.
Ddraig and Fafnir haven't been seen actively interacting with each other but it is shown that Ddraig is incredibly embarrassed by how the Dragon King acts to the point where he denied Fafnir's existence when Issei brought up how perverted he is.
Shown to know each other and also assisted in Ddraig's awakening in volume 14.