Fafnir

Fafnir is one of the Five Great Dragon Kings. He is the Golden Dragon known as the Gigantis Dragon.

Appearance
Fafnir is a golden Western Dragon, albeit without a pair of wings growing on his back like the usual Western Dragon.

Personality
Little is known of Fafnir's personality due to him being sealed in Azazel's Artificial Sacred Gear, as well as the fact that there are very few instances of him being described. As mentioned by Sona, Fafnir has a tendency to collect treasures throughout the world. In his first appearance, Fafnir is revealed to be a perverted Dragon with a fetish for panties, sniffing them and referring to them as "treasures".

History
Not much is known about Fafnir except that he was previously killed by the original Siegfried who wielded the Demon Sword Gram but was later revived by the Norse Gods. Prior to the series, he made a contract with Azazel to aide him in his Sacred Gear research by allowing himself to be sealed inside Azazel's Artificial Sacred Gear.

The Red Dragon Emperor's Awakening
In Volume 4, Azazel reveals that he made a pact with Fafnir to be sealed inside his Artificial Sacred Gear, the Down Fall Dragon Spear.

The Heroic Oppai Dragon
In Volume 10, Ddraig privately contacted Azazel through Fafnir's jewel to ask him to search for a Dragon Counselor as he has been crying unconciously.

The Legend of Oppai Dragon and his Lively Companions
In Volume 14, he made a pact with Asia after being freed of his own contract with Azazel. He also helped waked up Ddraig from his deep sleep with the help of Vritra during the attacked by Khaos Brigade on Kuoh Academy.

Powers & Abilities
As one of the Five Great Dragon Kings, it can be assumed that he is very powerful. Likely as powerful as an Ultimate-Class Devil. In his first shown battle, he released a golden block of aura from his mouth that extinguished Grendel’s flame, hinting that he has the ability to negate the power of his enemies.

Trivia

 * According to legend, Fafnir was actually a dwarf who took the form of a Dragon.